Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

10 files changed, 4572 insertions, 0 deletions

diff --git a/testing/geckodriver/src/android.rs b/testing/geckodriver/src/android.rs
new file mode 100644
index 0000000000..6aaf58ec6b
--- /dev/null
+++ b/testing/geckodriver/src/android.rs
@@ -0,0 +1,470 @@
+use crate::capabilities::AndroidOptions;
+use mozdevice::{AndroidStorage, Device, Host};
+use mozprofile::profile::Profile;
+use serde::Serialize;
+use serde_yaml::{Mapping, Value};
+use std::fmt;
+use std::io;
+use std::path::PathBuf;
+use std::time;
+use webdriver::error::{ErrorStatus, WebDriverError};
+
+// TODO: avoid port clashes across GeckoView-vehicles.
+// For now, we always use target port 2829, leading to issues like bug 1533704.
+const TARGET_PORT: u16 = 2829;
+
+const CONFIG_FILE_HEADING: &str = r#"## GeckoView configuration YAML
+##
+## Auto-generated by geckodriver.
+## See https://mozilla.github.io/geckoview/consumer/docs/automation.
+"#;
+
+pub type Result<T> = std::result::Result<T, AndroidError>;
+
+#[derive(Debug)]
+pub enum AndroidError {
+    ActivityNotFound(String),
+    Device(mozdevice::DeviceError),
+    IO(io::Error),
+    PackageNotFound(String),
+    Serde(serde_yaml::Error),
+}
+
+impl fmt::Display for AndroidError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            AndroidError::ActivityNotFound(ref package) => {
+                write!(f, "Activity for package '{}' not found", package)
+            }
+            AndroidError::Device(ref message) => message.fmt(f),
+            AndroidError::IO(ref message) => message.fmt(f),
+            AndroidError::PackageNotFound(ref package) => {
+                write!(f, "Package '{}' not found", package)
+            }
+            AndroidError::Serde(ref message) => message.fmt(f),
+        }
+    }
+}
+
+impl From<io::Error> for AndroidError {
+    fn from(value: io::Error) -> AndroidError {
+        AndroidError::IO(value)
+    }
+}
+
+impl From<mozdevice::DeviceError> for AndroidError {
+    fn from(value: mozdevice::DeviceError) -> AndroidError {
+        AndroidError::Device(value)
+    }
+}
+
+impl From<serde_yaml::Error> for AndroidError {
+    fn from(value: serde_yaml::Error) -> AndroidError {
+        AndroidError::Serde(value)
+    }
+}
+
+impl From<AndroidError> for WebDriverError {
+    fn from(value: AndroidError) -> WebDriverError {
+        WebDriverError::new(ErrorStatus::UnknownError, value.to_string())
+    }
+}
+
+/// A remote Gecko instance.
+///
+/// Host refers to the device running `geckodriver`.  Target refers to the
+/// Android device running Gecko in a GeckoView-based vehicle.
+#[derive(Debug)]
+pub struct AndroidProcess {
+    pub device: Device,
+    pub package: String,
+    pub activity: String,
+}
+
+impl AndroidProcess {
+    pub fn new(
+        device: Device,
+        package: String,
+        activity: String,
+    ) -> mozdevice::Result<AndroidProcess> {
+        Ok(AndroidProcess {
+            device,
+            package,
+            activity,
+        })
+    }
+}
+
+#[derive(Debug)]
+pub struct AndroidHandler {
+    pub config: PathBuf,
+    pub options: AndroidOptions,
+    pub process: AndroidProcess,
+    pub profile: PathBuf,
+    pub test_root: PathBuf,
+
+    // For port forwarding host => target
+    pub host_port: u16,
+    pub target_port: u16,
+}
+
+impl Drop for AndroidHandler {
+    fn drop(&mut self) {
+        // Try to clean up various settings
+        let clear_command = format!("am clear-debug-app {}", self.process.package);
+        match self
+            .process
+            .device
+            .execute_host_shell_command(&clear_command)
+        {
+            Ok(_) => debug!("Disabled reading from configuration file"),
+            Err(e) => error!("Failed disabling from configuration file: {}", e),
+        }
+
+        match self.process.device.remove(&self.config) {
+            Ok(_) => debug!("Deleted GeckoView configuration file"),
+            Err(e) => error!("Failed deleting GeckoView configuration file: {}", e),
+        }
+
+        match self.process.device.kill_forward_port(self.host_port) {
+            Ok(_) => debug!(
+                "Android port forward ({} -> {}) stopped",
+                &self.host_port, &self.target_port
+            ),
+            Err(e) => error!(
+                "Android port forward ({} -> {}) failed to stop: {}",
+                &self.host_port, &self.target_port, e
+            ),
+        }
+    }
+}
+
+impl AndroidHandler {
+    pub fn new(options: &AndroidOptions, host_port: u16) -> Result<AndroidHandler> {
+        // We need to push profile.pathbuf to a safe space on the device.
+        // Make it per-Android package to avoid clashes and confusion.
+        // This naming scheme follows GeckoView's configuration file naming scheme,
+        // see bug 1533385.
+
+        let host = Host {
+            host: None,
+            port: None,
+            read_timeout: Some(time::Duration::from_millis(5000)),
+            write_timeout: Some(time::Duration::from_millis(5000)),
+        };
+
+        let mut device = host.device_or_default(options.device_serial.as_ref(), options.storage)?;
+
+        // Set up port forward.  Port forwarding will be torn down, if possible,
+        device.forward_port(host_port, TARGET_PORT)?;
+        debug!(
+            "Android port forward ({} -> {}) started",
+            host_port, TARGET_PORT
+        );
+
+        let test_root = match device.storage {
+            AndroidStorage::App => {
+                device.run_as_package = Some(options.package.to_owned());
+                let mut buf = PathBuf::from("/data/data");
+                buf.push(&options.package);
+                buf.push("test_root");
+                buf
+            }
+            AndroidStorage::Internal => PathBuf::from("/data/local/tmp/test_root"),
+            AndroidStorage::Sdcard => PathBuf::from("/mnt/sdcard/test_root"),
+        };
+
+        debug!(
+            "Connecting: options={:?}, storage={:?}) test_root={}, run_as_package={:?}",
+            options,
+            device.storage,
+            test_root.display(),
+            device.run_as_package
+        );
+
+        let mut profile = test_root.clone();
+        profile.push(format!("{}-geckodriver-profile", &options.package));
+
+        // Check if the specified package is installed
+        let response =
+            device.execute_host_shell_command(&format!("pm list packages {}", &options.package))?;
+        let packages = response
+            .trim()
+            .split_terminator('\n')
+            .filter(|line| line.starts_with("package:"))
+            .map(|line| line.rsplit(':').next().expect("Package name found"))
+            .collect::<Vec<&str>>();
+        if !packages.contains(&options.package.as_str()) {
+            return Err(AndroidError::PackageNotFound(options.package.clone()));
+        }
+
+        let config = PathBuf::from(format!(
+            "/data/local/tmp/{}-geckoview-config.yaml",
+            &options.package
+        ));
+
+        // If activity hasn't been specified default to the main activity of the package
+        let activity = match options.activity {
+            Some(ref activity) => activity.clone(),
+            None => {
+                let response = device.execute_host_shell_command(&format!(
+                    "cmd package resolve-activity --brief {}",
+                    &options.package
+                ))?;
+                let activities = response
+                    .split_terminator('\n')
+                    .filter(|line| line.starts_with(&options.package))
+                    .map(|line| line.rsplit('/').next().unwrap())
+                    .collect::<Vec<&str>>();
+                if activities.is_empty() {
+                    return Err(AndroidError::ActivityNotFound(options.package.clone()));
+                }
+
+                activities[0].to_owned()
+            }
+        };
+
+        let process = AndroidProcess::new(device, options.package.clone(), activity)?;
+
+        Ok(AndroidHandler {
+            options: options.clone(),
+            config,
+            process,
+            profile,
+            test_root,
+            host_port,
+            target_port: TARGET_PORT,
+        })
+    }
+
+    pub fn generate_config_file<I, K, V>(&self, envs: I) -> Result<String>
+    where
+        I: IntoIterator<Item = (K, V)>,
+        K: ToString,
+        V: ToString,
+    {
+        // To configure GeckoView, we use the automation techniques documented at
+        // https://mozilla.github.io/geckoview/consumer/docs/automation.
+        #[derive(Serialize, Deserialize, PartialEq, Debug)]
+        pub struct Config {
+            pub env: Mapping,
+            pub args: Value,
+        }
+
+        // TODO: Allow to write custom arguments and preferences from moz:firefoxOptions
+        let mut config = Config {
+            args: Value::Sequence(vec![
+                Value::String("--marionette".into()),
+                Value::String("--profile".into()),
+                Value::String(self.profile.display().to_string()),
+            ]),
+            env: Mapping::new(),
+        };
+
+        for (key, value) in envs {
+            config.env.insert(
+                Value::String(key.to_string()),
+                Value::String(value.to_string()),
+            );
+        }
+
+        config.env.insert(
+            Value::String("MOZ_CRASHREPORTER".to_owned()),
+            Value::String("1".to_owned()),
+        );
+        config.env.insert(
+            Value::String("MOZ_CRASHREPORTER_NO_REPORT".to_owned()),
+            Value::String("1".to_owned()),
+        );
+        config.env.insert(
+            Value::String("MOZ_CRASHREPORTER_SHUTDOWN".to_owned()),
+            Value::String("1".to_owned()),
+        );
+
+        let mut contents: Vec<String> = vec![CONFIG_FILE_HEADING.to_owned()];
+        contents.push(serde_yaml::to_string(&config)?);
+
+        Ok(contents.concat())
+    }
+
+    pub fn prepare<I, K, V>(&self, profile: &Profile, env: I) -> Result<()>
+    where
+        I: IntoIterator<Item = (K, V)>,
+        K: ToString,
+        V: ToString,
+    {
+        self.process.device.clear_app_data(&self.process.package)?;
+
+        // These permissions, at least, are required to read profiles in /mnt/sdcard.
+        for perm in &["READ_EXTERNAL_STORAGE", "WRITE_EXTERNAL_STORAGE"] {
+            self.process.device.execute_host_shell_command(&format!(
+                "pm grant {} android.permission.{}",
+                &self.process.package, perm
+            ))?;
+        }
+
+        // Make sure to create the test root.
+        self.process.device.create_dir(&self.test_root)?;
+        self.process.device.chmod(&self.test_root, "777", true)?;
+
+        // Replace the profile
+        self.process.device.remove(&self.profile)?;
+        self.process
+            .device
+            .push_dir(&profile.path, &self.profile, 0o777)?;
+
+        let contents = self.generate_config_file(env)?;
+        debug!("Content of generated GeckoView config file:\n{}", contents);
+        let reader = &mut io::BufReader::new(contents.as_bytes());
+
+        debug!(
+            "Pushing GeckoView configuration file to {}",
+            self.config.display()
+        );
+        self.process.device.push(reader, &self.config, 0o777)?;
+
+        // Tell GeckoView to read configuration even when `android:debuggable="false"`.
+        self.process.device.execute_host_shell_command(&format!(
+            "am set-debug-app --persistent {}",
+            self.process.package
+        ))?;
+
+        Ok(())
+    }
+
+    pub fn launch(&self) -> Result<()> {
+        // TODO: Remove the usage of intent arguments once Fennec is no longer
+        // supported. Packages which are using GeckoView always read the arguments
+        // via the YAML configuration file.
+        let mut intent_arguments = self
+            .options
+            .intent_arguments
+            .clone()
+            .unwrap_or_else(|| Vec::with_capacity(3));
+        intent_arguments.push("--es".to_owned());
+        intent_arguments.push("args".to_owned());
+        intent_arguments.push(format!("--marionette --profile {}", self.profile.display()));
+
+        debug!(
+            "Launching {}/{}",
+            self.process.package, self.process.activity
+        );
+        self.process
+            .device
+            .launch(
+                &self.process.package,
+                &self.process.activity,
+                &intent_arguments,
+            )
+            .map_err(|e| {
+                let message = format!(
+                    "Could not launch Android {}/{}: {}",
+                    self.process.package, self.process.activity, e
+                );
+                mozdevice::DeviceError::Adb(message)
+            })?;
+
+        Ok(())
+    }
+
+    pub fn force_stop(&self) -> Result<()> {
+        debug!(
+            "Force stopping the Android package: {}",
+            &self.process.package
+        );
+        self.process.device.force_stop(&self.process.package)?;
+
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    // To successfully run those tests the geckoview_example package needs to
+    // be installed on the device or emulator. After setting up the build
+    // environment (https://mzl.la/3muLv5M), the following mach commands have to
+    // be executed:
+    //
+    //     $ ./mach build && ./mach install
+    //
+    // Currently the mozdevice API is not safe for multiple requests at the same
+    // time. It is recommended to run each of the unit tests on its own. Also adb
+    // specific tests cannot be run in CI yet. To check those locally, also run
+    // the ignored tests.
+    //
+    // Use the following command to accomplish that:
+    //
+    //     $ cargo test -- --ignored --test-threads=1
+
+    use crate::android::AndroidHandler;
+    use crate::capabilities::AndroidOptions;
+    use mozdevice::{AndroidStorage, AndroidStorageInput};
+    use std::path::PathBuf;
+
+    fn run_handler_storage_test(package: &str, storage: AndroidStorageInput) {
+        let options = AndroidOptions::new(package.to_owned(), storage);
+        let handler = AndroidHandler::new(&options, 4242).expect("has valid Android handler");
+
+        assert_eq!(handler.options, options);
+        assert_eq!(handler.process.package, package);
+
+        let expected_config_path = PathBuf::from(format!(
+            "/data/local/tmp/{}-geckoview-config.yaml",
+            &package
+        ));
+        assert_eq!(handler.config, expected_config_path);
+
+        if handler.process.device.storage == AndroidStorage::App {
+            assert_eq!(
+                handler.process.device.run_as_package,
+                Some(package.to_owned())
+            );
+        } else {
+            assert_eq!(handler.process.device.run_as_package, None);
+        }
+
+        let test_root = match handler.process.device.storage {
+            AndroidStorage::App => {
+                let mut buf = PathBuf::from("/data/data");
+                buf.push(&package);
+                buf.push("test_root");
+                buf
+            }
+            AndroidStorage::Internal => PathBuf::from("/data/local/tmp/test_root"),
+            AndroidStorage::Sdcard => PathBuf::from("/mnt/sdcard/test_root"),
+        };
+        assert_eq!(handler.test_root, test_root);
+
+        let mut profile = test_root.clone();
+        profile.push(format!("{}-geckodriver-profile", &package));
+        assert_eq!(handler.profile, profile);
+    }
+
+    #[test]
+    #[ignore]
+    fn android_handler_storage_as_app() {
+        let package = "org.mozilla.geckoview_example";
+        run_handler_storage_test(&package, AndroidStorageInput::App);
+    }
+
+    #[test]
+    #[ignore]
+    fn android_handler_storage_as_auto() {
+        let package = "org.mozilla.geckoview_example";
+        run_handler_storage_test(package, AndroidStorageInput::Auto);
+    }
+
+    #[test]
+    #[ignore]
+    fn android_handler_storage_as_internal() {
+        let package = "org.mozilla.geckoview_example";
+        run_handler_storage_test(package, AndroidStorageInput::Internal);
+    }
+
+    #[test]
+    #[ignore]
+    fn android_handler_storage_as_sdcard() {
+        let package = "org.mozilla.geckoview_example";
+        run_handler_storage_test(package, AndroidStorageInput::Sdcard);
+    }
+}
diff --git a/testing/geckodriver/src/build.rs b/testing/geckodriver/src/build.rs
new file mode 100644
index 0000000000..7ba3144755
--- /dev/null
+++ b/testing/geckodriver/src/build.rs
@@ -0,0 +1,49 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use serde_json::Value;
+use std::fmt;
+
+include!(concat!(env!("OUT_DIR"), "/build-info.rs"));
+
+pub struct BuildInfo;
+
+impl BuildInfo {
+    pub fn version() -> &'static str {
+        crate_version!()
+    }
+
+    pub fn hash() -> Option<&'static str> {
+        COMMIT_HASH
+    }
+
+    pub fn date() -> Option<&'static str> {
+        COMMIT_DATE
+    }
+}
+
+impl fmt::Display for BuildInfo {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", BuildInfo::version())?;
+        match (BuildInfo::hash(), BuildInfo::date()) {
+            (Some(hash), Some(date)) => write!(f, " ({} {})", hash, date)?,
+            (Some(hash), None) => write!(f, " ({})", hash)?,
+            _ => {}
+        }
+        Ok(())
+    }
+}
+
+// TODO(Henrik): Change into From
+//std::convert::From<&str>` is not implemented for `rustc_serialize::json::Json
+impl Into<Value> for BuildInfo {
+    fn into(self) -> Value {
+        Value::String(BuildInfo::version().to_string())
+    }
+}
+
+/// Returns build-time information about geckodriver.
+pub fn build_info() -> BuildInfo {
+    BuildInfo {}
+}
diff --git a/testing/geckodriver/src/capabilities.rs b/testing/geckodriver/src/capabilities.rs
new file mode 100644
index 0000000000..e21651ea61
--- /dev/null
+++ b/testing/geckodriver/src/capabilities.rs
@@ -0,0 +1,1088 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use crate::command::LogOptions;
+use crate::logging::Level;
+use base64;
+use mozdevice::AndroidStorageInput;
+use mozprofile::preferences::Pref;
+use mozprofile::profile::Profile;
+use mozrunner::runner::platform::firefox_default_path;
+use mozversion::{self, firefox_binary_version, firefox_version, Version};
+use regex::bytes::Regex;
+use serde_json::{Map, Value};
+use std::collections::BTreeMap;
+use std::default::Default;
+use std::fmt::{self, Display};
+use std::fs;
+use std::io;
+use std::io::BufWriter;
+use std::io::Cursor;
+use std::path::{Path, PathBuf};
+use std::str::{self, FromStr};
+use webdriver::capabilities::{BrowserCapabilities, Capabilities};
+use webdriver::error::{ErrorStatus, WebDriverError, WebDriverResult};
+use zip;
+
+#[derive(Clone, Debug)]
+enum VersionError {
+    VersionError(mozversion::Error),
+    MissingBinary,
+}
+
+impl From<mozversion::Error> for VersionError {
+    fn from(err: mozversion::Error) -> VersionError {
+        VersionError::VersionError(err)
+    }
+}
+
+impl Display for VersionError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            VersionError::VersionError(ref x) => x.fmt(f),
+            VersionError::MissingBinary => "No binary provided".fmt(f),
+        }
+    }
+}
+
+impl From<VersionError> for WebDriverError {
+    fn from(err: VersionError) -> WebDriverError {
+        WebDriverError::new(ErrorStatus::SessionNotCreated, err.to_string())
+    }
+}
+
+/// Provides matching of `moz:firefoxOptions` and resolutionnized  of which Firefox
+/// binary to use.
+///
+/// `FirefoxCapabilities` is constructed with the fallback binary, should
+/// `moz:firefoxOptions` not contain a binary entry.  This may either be the
+/// system Firefox installation or an override, for example given to the
+/// `--binary` flag of geckodriver.
+pub struct FirefoxCapabilities<'a> {
+    pub chosen_binary: Option<PathBuf>,
+    fallback_binary: Option<&'a PathBuf>,
+    version_cache: BTreeMap<PathBuf, Result<Version, VersionError>>,
+}
+
+impl<'a> FirefoxCapabilities<'a> {
+    pub fn new(fallback_binary: Option<&'a PathBuf>) -> FirefoxCapabilities<'a> {
+        FirefoxCapabilities {
+            chosen_binary: None,
+            fallback_binary,
+            version_cache: BTreeMap::new(),
+        }
+    }
+
+    fn set_binary(&mut self, capabilities: &Map<String, Value>) {
+        self.chosen_binary = capabilities
+            .get("moz:firefoxOptions")
+            .and_then(|x| x.get("binary"))
+            .and_then(|x| x.as_str())
+            .map(PathBuf::from)
+            .or_else(|| self.fallback_binary.cloned())
+            .or_else(firefox_default_path);
+    }
+
+    fn version(&mut self, binary: Option<&Path>) -> Result<Version, VersionError> {
+        if let Some(binary) = binary {
+            if let Some(cache_value) = self.version_cache.get(binary) {
+                return cache_value.clone();
+            }
+            let rv = self
+                .version_from_ini(binary)
+                .or_else(|_| self.version_from_binary(binary));
+            if let Ok(ref version) = rv {
+                debug!("Found version {}", version);
+            } else {
+                debug!("Failed to get binary version");
+            }
+            self.version_cache.insert(binary.to_path_buf(), rv.clone());
+            rv
+        } else {
+            Err(VersionError::MissingBinary)
+        }
+    }
+
+    fn version_from_ini(&self, binary: &Path) -> Result<Version, VersionError> {
+        debug!("Trying to read firefox version from ini files");
+        let version = firefox_version(binary)?;
+        if let Some(version_string) = version.version_string {
+            Version::from_str(&version_string).map_err(|err| err.into())
+        } else {
+            Err(VersionError::VersionError(
+                mozversion::Error::MetadataError("Missing version string".into()),
+            ))
+        }
+    }
+
+    fn version_from_binary(&self, binary: &Path) -> Result<Version, VersionError> {
+        debug!("Trying to read firefox version from binary");
+        Ok(firefox_binary_version(binary)?)
+    }
+}
+
+impl<'a> BrowserCapabilities for FirefoxCapabilities<'a> {
+    fn init(&mut self, capabilities: &Capabilities) {
+        self.set_binary(capabilities);
+    }
+
+    fn browser_name(&mut self, _: &Capabilities) -> WebDriverResult<Option<String>> {
+        Ok(Some("firefox".into()))
+    }
+
+    fn browser_version(&mut self, _: &Capabilities) -> WebDriverResult<Option<String>> {
+        let binary = self.chosen_binary.clone();
+        self.version(binary.as_ref().map(|x| x.as_ref()))
+            .map_err(|err| err.into())
+            .map(|x| Some(x.to_string()))
+    }
+
+    fn platform_name(&mut self, _: &Capabilities) -> WebDriverResult<Option<String>> {
+        Ok(if cfg!(target_os = "windows") {
+            Some("windows".into())
+        } else if cfg!(target_os = "macos") {
+            Some("mac".into())
+        } else if cfg!(target_os = "linux") {
+            Some("linux".into())
+        } else {
+            None
+        })
+    }
+
+    fn accept_insecure_certs(&mut self, _: &Capabilities) -> WebDriverResult<bool> {
+        Ok(true)
+    }
+
+    fn set_window_rect(&mut self, _: &Capabilities) -> WebDriverResult<bool> {
+        Ok(true)
+    }
+
+    fn compare_browser_version(
+        &mut self,
+        version: &str,
+        comparison: &str,
+    ) -> WebDriverResult<bool> {
+        Version::from_str(version)
+            .map_err(|err| VersionError::from(err))?
+            .matches(comparison)
+            .map_err(|err| VersionError::from(err).into())
+    }
+
+    fn strict_file_interactability(&mut self, _: &Capabilities) -> WebDriverResult<bool> {
+        Ok(true)
+    }
+
+    fn accept_proxy(&mut self, _: &Capabilities, _: &Capabilities) -> WebDriverResult<bool> {
+        Ok(true)
+    }
+
+    fn validate_custom(&mut self, name: &str, value: &Value) -> WebDriverResult<()> {
+        if !name.starts_with("moz:") {
+            return Ok(());
+        }
+        match name {
+            "moz:firefoxOptions" => {
+                let data = try_opt!(
+                    value.as_object(),
+                    ErrorStatus::InvalidArgument,
+                    "moz:firefoxOptions is not an object"
+                );
+                for (key, value) in data.iter() {
+                    match &**key {
+                        "androidActivity"
+                        | "androidDeviceSerial"
+                        | "androidPackage"
+                        | "profile" => {
+                            if !value.is_string() {
+                                return Err(WebDriverError::new(
+                                    ErrorStatus::InvalidArgument,
+                                    format!("{} is not a string", &**key),
+                                ));
+                            }
+                        }
+                        "androidIntentArguments" | "args" => {
+                            if !try_opt!(
+                                value.as_array(),
+                                ErrorStatus::InvalidArgument,
+                                format!("{} is not an array", &**key)
+                            )
+                            .iter()
+                            .all(|value| value.is_string())
+                            {
+                                return Err(WebDriverError::new(
+                                    ErrorStatus::InvalidArgument,
+                                    format!("{} entry is not a string", &**key),
+                                ));
+                            }
+                        }
+                        "binary" => {
+                            if let Some(binary) = value.as_str() {
+                                if !data.contains_key("androidPackage")
+                                    && self.version(Some(Path::new(binary))).is_err()
+                                {
+                                    return Err(WebDriverError::new(
+                                        ErrorStatus::InvalidArgument,
+                                        format!("{} is not a Firefox executable", &**key),
+                                    ));
+                                }
+                            } else {
+                                return Err(WebDriverError::new(
+                                    ErrorStatus::InvalidArgument,
+                                    format!("{} is not a string", &**key),
+                                ));
+                            }
+                        }
+                        "env" => {
+                            let env_data = try_opt!(
+                                value.as_object(),
+                                ErrorStatus::InvalidArgument,
+                                "env value is not an object"
+                            );
+                            if !env_data.values().all(Value::is_string) {
+                                return Err(WebDriverError::new(
+                                    ErrorStatus::InvalidArgument,
+                                    "Environment values were not all strings",
+                                ));
+                            }
+                        }
+                        "log" => {
+                            let log_data = try_opt!(
+                                value.as_object(),
+                                ErrorStatus::InvalidArgument,
+                                "log value is not an object"
+                            );
+                            for (log_key, log_value) in log_data.iter() {
+                                match &**log_key {
+                                    "level" => {
+                                        let level = try_opt!(
+                                            log_value.as_str(),
+                                            ErrorStatus::InvalidArgument,
+                                            "log level is not a string"
+                                        );
+                                        if Level::from_str(level).is_err() {
+                                            return Err(WebDriverError::new(
+                                                ErrorStatus::InvalidArgument,
+                                                format!("Not a valid log level: {}", level),
+                                            ));
+                                        }
+                                    }
+                                    x => {
+                                        return Err(WebDriverError::new(
+                                            ErrorStatus::InvalidArgument,
+                                            format!("Invalid log field {}", x),
+                                        ))
+                                    }
+                                }
+                            }
+                        }
+                        "prefs" => {
+                            let prefs_data = try_opt!(
+                                value.as_object(),
+                                ErrorStatus::InvalidArgument,
+                                "prefs value is not an object"
+                            );
+                            let is_pref_value_type = |x: &Value| {
+                                x.is_string() || x.is_i64() || x.is_u64() || x.is_boolean()
+                            };
+                            if !prefs_data.values().all(is_pref_value_type) {
+                                return Err(WebDriverError::new(
+                                    ErrorStatus::InvalidArgument,
+                                    "Preference values not all string or integer or boolean",
+                                ));
+                            }
+                        }
+                        x => {
+                            return Err(WebDriverError::new(
+                                ErrorStatus::InvalidArgument,
+                                format!("Invalid moz:firefoxOptions field {}", x),
+                            ))
+                        }
+                    }
+                }
+            }
+            "moz:useNonSpecCompliantPointerOrigin" => {
+                if !value.is_boolean() {
+                    return Err(WebDriverError::new(
+                        ErrorStatus::InvalidArgument,
+                        "moz:useNonSpecCompliantPointerOrigin is not a boolean",
+                    ));
+                }
+            }
+            "moz:webdriverClick" => {
+                if !value.is_boolean() {
+                    return Err(WebDriverError::new(
+                        ErrorStatus::InvalidArgument,
+                        "moz:webdriverClick is not a boolean",
+                    ));
+                }
+            }
+            "moz:debuggerAddress" => {
+                if !value.is_boolean() {
+                    return Err(WebDriverError::new(
+                        ErrorStatus::InvalidArgument,
+                        "moz:debuggerAddress is not a boolean",
+                    ));
+                }
+            }
+            _ => {
+                return Err(WebDriverError::new(
+                    ErrorStatus::InvalidArgument,
+                    format!("Unrecognised option {}", name),
+                ))
+            }
+        }
+        Ok(())
+    }
+
+    fn accept_custom(&mut self, _: &str, _: &Value, _: &Capabilities) -> WebDriverResult<bool> {
+        Ok(true)
+    }
+}
+
+/// Android-specific options in the `moz:firefoxOptions` struct.
+/// These map to "androidCamelCase", following [chromedriver's Android-specific
+/// Capabilities](http://chromedriver.chromium.org/getting-started/getting-started---android).
+#[derive(Default, Clone, Debug, PartialEq)]
+pub struct AndroidOptions {
+    pub activity: Option<String>,
+    pub device_serial: Option<String>,
+    pub intent_arguments: Option<Vec<String>>,
+    pub package: String,
+    pub storage: AndroidStorageInput,
+}
+
+impl AndroidOptions {
+    pub fn new(package: String, storage: AndroidStorageInput) -> AndroidOptions {
+        AndroidOptions {
+            package,
+            storage,
+            ..Default::default()
+        }
+    }
+}
+
+/// Rust representation of `moz:firefoxOptions`.
+///
+/// Calling `FirefoxOptions::from_capabilities(binary, capabilities)` causes
+/// the encoded profile, the binary arguments, log settings, and additional
+/// preferences to be checked and unmarshaled from the `moz:firefoxOptions`
+/// JSON Object into a Rust representation.
+#[derive(Default, Debug)]
+pub struct FirefoxOptions {
+    pub binary: Option<PathBuf>,
+    pub profile: Option<Profile>,
+    pub args: Option<Vec<String>>,
+    pub env: Option<Vec<(String, String)>>,
+    pub log: LogOptions,
+    pub prefs: Vec<(String, Pref)>,
+    pub android: Option<AndroidOptions>,
+}
+
+impl FirefoxOptions {
+    pub fn new() -> FirefoxOptions {
+        Default::default()
+    }
+
+    pub fn from_capabilities(
+        binary_path: Option<PathBuf>,
+        android_storage: AndroidStorageInput,
+        matched: &mut Capabilities,
+    ) -> WebDriverResult<FirefoxOptions> {
+        let mut rv = FirefoxOptions::new();
+        rv.binary = binary_path;
+
+        if let Some(json) = matched.remove("moz:firefoxOptions") {
+            let options = json.as_object().ok_or_else(|| {
+                WebDriverError::new(
+                    ErrorStatus::InvalidArgument,
+                    "'moz:firefoxOptions' \
+                 capability is not an object",
+                )
+            })?;
+
+            rv.android = FirefoxOptions::load_android(android_storage, &options)?;
+            rv.args = FirefoxOptions::load_args(&options)?;
+            rv.env = FirefoxOptions::load_env(&options)?;
+            rv.log = FirefoxOptions::load_log(&options)?;
+            rv.prefs = FirefoxOptions::load_prefs(&options)?;
+            rv.profile = FirefoxOptions::load_profile(&options)?;
+        }
+
+        if let Some(json) = matched.remove("moz:debuggerAddress") {
+            let use_web_socket = json.as_bool().ok_or_else(|| {
+                WebDriverError::new(
+                    ErrorStatus::InvalidArgument,
+                    "moz:debuggerAddress is not a boolean",
+                )
+            })?;
+
+            if use_web_socket {
+                let mut remote_args = Vec::new();
+                remote_args.push("--remote-debugging-port".to_owned());
+                remote_args.push("0".to_owned());
+
+                if let Some(ref mut args) = rv.args {
+                    args.append(&mut remote_args);
+                } else {
+                    rv.args = Some(remote_args);
+                }
+
+                // Force Fission disabled until Remote Agent is compatible,
+                // and preference hasn't been already set
+                let has_fission_pref = rv.prefs.iter().find(|&x| x.0 == "fission.autostart");
+                if has_fission_pref.is_none() {
+                    rv.prefs
+                        .push(("fission.autostart".to_owned(), Pref::new(false)));
+                }
+            }
+        }
+
+        Ok(rv)
+    }
+
+    fn load_profile(options: &Capabilities) -> WebDriverResult<Option<Profile>> {
+        if let Some(profile_json) = options.get("profile") {
+            let profile_base64 = profile_json.as_str().ok_or_else(|| {
+                WebDriverError::new(ErrorStatus::InvalidArgument, "Profile is not a string")
+            })?;
+            let profile_zip = &*base64::decode(profile_base64)?;
+
+            // Create an emtpy profile directory
+            let profile = Profile::new()?;
+            unzip_buffer(
+                profile_zip,
+                profile
+                    .temp_dir
+                    .as_ref()
+                    .expect("Profile doesn't have a path")
+                    .path(),
+            )?;
+
+            Ok(Some(profile))
+        } else {
+            Ok(None)
+        }
+    }
+
+    fn load_args(options: &Capabilities) -> WebDriverResult<Option<Vec<String>>> {
+        if let Some(args_json) = options.get("args") {
+            let args_array = args_json.as_array().ok_or_else(|| {
+                WebDriverError::new(
+                    ErrorStatus::InvalidArgument,
+                    "Arguments were not an \
+                 array",
+                )
+            })?;
+            let args = args_array
+                .iter()
+                .map(|x| x.as_str().map(|x| x.to_owned()))
+                .collect::<Option<Vec<String>>>()
+                .ok_or_else(|| {
+                    WebDriverError::new(
+                        ErrorStatus::InvalidArgument,
+                        "Arguments entries were not all strings",
+                    )
+                })?;
+            Ok(Some(args))
+        } else {
+            Ok(None)
+        }
+    }
+
+    pub fn load_env(options: &Capabilities) -> WebDriverResult<Option<Vec<(String, String)>>> {
+        if let Some(env_data) = options.get("env") {
+            let env = env_data.as_object().ok_or_else(|| {
+                WebDriverError::new(ErrorStatus::InvalidArgument, "Env was not an object")
+            })?;
+            let mut rv = Vec::with_capacity(env.len());
+            for (key, value) in env.iter() {
+                rv.push((
+                    key.clone(),
+                    value
+                        .as_str()
+                        .ok_or_else(|| {
+                            WebDriverError::new(
+                                ErrorStatus::InvalidArgument,
+                                "Env value is not a string",
+                            )
+                        })?
+                        .to_string(),
+                ));
+            }
+            Ok(Some(rv))
+        } else {
+            Ok(None)
+        }
+    }
+
+    fn load_log(options: &Capabilities) -> WebDriverResult<LogOptions> {
+        if let Some(json) = options.get("log") {
+            let log = json.as_object().ok_or_else(|| {
+                WebDriverError::new(ErrorStatus::InvalidArgument, "Log section is not an object")
+            })?;
+
+            let level = match log.get("level") {
+                Some(json) => {
+                    let s = json.as_str().ok_or_else(|| {
+                        WebDriverError::new(
+                            ErrorStatus::InvalidArgument,
+                            "Log level is not a string",
+                        )
+                    })?;
+                    Some(Level::from_str(s).ok().ok_or_else(|| {
+                        WebDriverError::new(ErrorStatus::InvalidArgument, "Log level is unknown")
+                    })?)
+                }
+                None => None,
+            };
+
+            Ok(LogOptions { level })
+        } else {
+            Ok(Default::default())
+        }
+    }
+
+    pub fn load_prefs(options: &Capabilities) -> WebDriverResult<Vec<(String, Pref)>> {
+        if let Some(prefs_data) = options.get("prefs") {
+            let prefs = prefs_data.as_object().ok_or_else(|| {
+                WebDriverError::new(ErrorStatus::InvalidArgument, "Prefs were not an object")
+            })?;
+            let mut rv = Vec::with_capacity(prefs.len());
+            for (key, value) in prefs.iter() {
+                rv.push((key.clone(), pref_from_json(value)?));
+            }
+            Ok(rv)
+        } else {
+            Ok(vec![])
+        }
+    }
+
+    pub fn load_android(
+        storage: AndroidStorageInput,
+        options: &Capabilities,
+    ) -> WebDriverResult<Option<AndroidOptions>> {
+        if let Some(package_json) = options.get("androidPackage") {
+            let package = package_json
+                .as_str()
+                .ok_or_else(|| {
+                    WebDriverError::new(
+                        ErrorStatus::InvalidArgument,
+                        "androidPackage is not a string",
+                    )
+                })?
+                .to_owned();
+
+            // https://developer.android.com/studio/build/application-id
+            let package_regexp =
+                Regex::new(r#"^([a-zA-Z][a-zA-Z0-9_]*\.){1,}([a-zA-Z][a-zA-Z0-9_]*)$"#).unwrap();
+            if !package_regexp.is_match(package.as_bytes()) {
+                return Err(WebDriverError::new(
+                    ErrorStatus::InvalidArgument,
+                    "Not a valid androidPackage name",
+                ));
+            }
+
+            let mut android = AndroidOptions::new(package, storage);
+
+            android.activity = match options.get("androidActivity") {
+                Some(json) => {
+                    let activity = json
+                        .as_str()
+                        .ok_or_else(|| {
+                            WebDriverError::new(
+                                ErrorStatus::InvalidArgument,
+                                "androidActivity is not a string",
+                            )
+                        })?
+                        .to_owned();
+
+                    if activity.contains("/") {
+                        return Err(WebDriverError::new(
+                            ErrorStatus::InvalidArgument,
+                            "androidActivity should not contain '/",
+                        ));
+                    }
+
+                    Some(activity)
+                }
+                None => None,
+            };
+
+            android.device_serial = match options.get("androidDeviceSerial") {
+                Some(json) => Some(
+                    json.as_str()
+                        .ok_or_else(|| {
+                            WebDriverError::new(
+                                ErrorStatus::InvalidArgument,
+                                "androidDeviceSerial is not a string",
+                            )
+                        })?
+                        .to_owned(),
+                ),
+                None => None,
+            };
+
+            android.intent_arguments = match options.get("androidIntentArguments") {
+                Some(json) => {
+                    let args_array = json.as_array().ok_or_else(|| {
+                        WebDriverError::new(
+                            ErrorStatus::InvalidArgument,
+                            "androidIntentArguments is not an array",
+                        )
+                    })?;
+                    let args = args_array
+                        .iter()
+                        .map(|x| x.as_str().map(|x| x.to_owned()))
+                        .collect::<Option<Vec<String>>>()
+                        .ok_or_else(|| {
+                            WebDriverError::new(
+                                ErrorStatus::InvalidArgument,
+                                "androidIntentArguments entries are not all strings",
+                            )
+                        })?;
+
+                    Some(args)
+                }
+                None => None,
+            };
+
+            Ok(Some(android))
+        } else {
+            Ok(None)
+        }
+    }
+}
+
+fn pref_from_json(value: &Value) -> WebDriverResult<Pref> {
+    match *value {
+        Value::String(ref x) => Ok(Pref::new(x.clone())),
+        Value::Number(ref x) => Ok(Pref::new(x.as_i64().unwrap())),
+        Value::Bool(x) => Ok(Pref::new(x)),
+        _ => Err(WebDriverError::new(
+            ErrorStatus::UnknownError,
+            "Could not convert pref value to string, boolean, or integer",
+        )),
+    }
+}
+
+fn unzip_buffer(buf: &[u8], dest_dir: &Path) -> WebDriverResult<()> {
+    let reader = Cursor::new(buf);
+    let mut zip = zip::ZipArchive::new(reader)
+        .map_err(|_| WebDriverError::new(ErrorStatus::UnknownError, "Failed to unzip profile"))?;
+
+    for i in 0..zip.len() {
+        let mut file = zip.by_index(i).map_err(|_| {
+            WebDriverError::new(
+                ErrorStatus::UnknownError,
+                "Processing profile zip file failed",
+            )
+        })?;
+        let unzip_path = {
+            let name = file.name();
+            let is_dir = name.ends_with('/');
+            let rel_path = Path::new(name);
+            let dest_path = dest_dir.join(rel_path);
+
+            {
+                let create_dir = if is_dir {
+                    Some(dest_path.as_path())
+                } else {
+                    dest_path.parent()
+                };
+                if let Some(dir) = create_dir {
+                    if !dir.exists() {
+                        debug!("Creating profile directory tree {}", dir.to_string_lossy());
+                        fs::create_dir_all(dir)?;
+                    }
+                }
+            }
+
+            if is_dir {
+                None
+            } else {
+                Some(dest_path)
+            }
+        };
+
+        if let Some(unzip_path) = unzip_path {
+            debug!("Extracting profile to {}", unzip_path.to_string_lossy());
+            let dest = fs::File::create(unzip_path)?;
+            if file.size() > 0 {
+                let mut writer = BufWriter::new(dest);
+                io::copy(&mut file, &mut writer)?;
+            }
+        }
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    extern crate mozprofile;
+
+    use self::mozprofile::preferences::Pref;
+    use super::*;
+    use crate::marionette::MarionetteHandler;
+    use mozdevice::AndroidStorageInput;
+    use serde_json::json;
+    use std::default::Default;
+    use std::fs::File;
+    use std::io::Read;
+
+    use webdriver::capabilities::Capabilities;
+
+    fn example_profile() -> Value {
+        let mut profile_data = Vec::with_capacity(1024);
+        let mut profile = File::open("src/tests/profile.zip").unwrap();
+        profile.read_to_end(&mut profile_data).unwrap();
+        Value::String(base64::encode(&profile_data))
+    }
+
+    fn make_options(firefox_opts: Capabilities) -> WebDriverResult<FirefoxOptions> {
+        let mut caps = Capabilities::new();
+        caps.insert("moz:firefoxOptions".into(), Value::Object(firefox_opts));
+
+        FirefoxOptions::from_capabilities(None, AndroidStorageInput::Auto, &mut caps)
+    }
+
+    #[test]
+    fn fx_options_default() {
+        let opts = FirefoxOptions::new();
+        assert_eq!(opts.android, None);
+        assert_eq!(opts.args, None);
+        assert_eq!(opts.binary, None);
+        assert_eq!(opts.log, LogOptions { level: None });
+        assert_eq!(opts.prefs, vec![]);
+        // Profile doesn't support PartialEq
+        // assert_eq!(opts.profile, None);
+    }
+
+    #[test]
+    fn fx_options_from_capabilities_no_binary_and_caps() {
+        let mut caps = Capabilities::new();
+
+        let opts =
+            FirefoxOptions::from_capabilities(None, AndroidStorageInput::Auto, &mut caps).unwrap();
+        assert_eq!(opts.android, None);
+        assert_eq!(opts.args, None);
+        assert_eq!(opts.binary, None);
+        assert_eq!(opts.log, LogOptions { level: None });
+        assert_eq!(opts.prefs, vec![]);
+    }
+
+    #[test]
+    fn fx_options_from_capabilities_with_binary_and_caps() {
+        let mut caps = Capabilities::new();
+        caps.insert(
+            "moz:firefoxOptions".into(),
+            Value::Object(Capabilities::new()),
+        );
+
+        let binary = PathBuf::from("foo");
+
+        let opts = FirefoxOptions::from_capabilities(
+            Some(binary.clone()),
+            AndroidStorageInput::Auto,
+            &mut caps,
+        )
+        .unwrap();
+        assert_eq!(opts.android, None);
+        assert_eq!(opts.args, None);
+        assert_eq!(opts.binary, Some(binary));
+        assert_eq!(opts.log, LogOptions { level: None });
+        assert_eq!(opts.prefs, vec![]);
+    }
+
+    #[test]
+    fn fx_options_from_capabilities_with_debugger_address_not_set() {
+        let mut caps = Capabilities::new();
+
+        let opts = FirefoxOptions::from_capabilities(None, AndroidStorageInput::Auto, &mut caps)
+            .expect("Valid Firefox options");
+
+        assert!(
+            opts.args.is_none(),
+            "CLI arguments for Firefox unexpectedly found"
+        );
+    }
+
+    #[test]
+    fn fx_options_from_capabilities_with_debugger_address_false() {
+        let mut caps = Capabilities::new();
+        caps.insert("moz:debuggerAddress".into(), json!(false));
+
+        let opts = FirefoxOptions::from_capabilities(None, AndroidStorageInput::Auto, &mut caps)
+            .expect("Valid Firefox options");
+
+        assert!(
+            opts.args.is_none(),
+            "CLI arguments for remote protocol unexpectedly found"
+        );
+    }
+
+    #[test]
+    fn fx_options_from_capabilities_with_debugger_address_true() {
+        let mut caps = Capabilities::new();
+        caps.insert("moz:debuggerAddress".into(), json!(true));
+
+        let opts = FirefoxOptions::from_capabilities(None, AndroidStorageInput::Auto, &mut caps)
+            .expect("Valid Firefox options");
+
+        if let Some(args) = opts.args {
+            let mut iter = args.iter();
+            assert!(iter
+                .find(|&arg| arg == &"--remote-debugging-port".to_owned())
+                .is_some());
+            assert_eq!(iter.next(), Some(&"0".to_owned()));
+        } else {
+            assert!(false, "CLI arguments for remote protocol not found");
+        }
+
+        assert!(opts
+            .prefs
+            .iter()
+            .any(|pref| pref == &("fission.autostart".to_owned(), Pref::new(false))));
+    }
+
+    #[test]
+    fn fx_options_from_capabilities_with_invalid_caps() {
+        let mut caps = Capabilities::new();
+        caps.insert("moz:firefoxOptions".into(), json!(42));
+
+        FirefoxOptions::from_capabilities(None, AndroidStorageInput::Auto, &mut caps)
+            .expect_err("Firefox options need to be of type object");
+    }
+
+    #[test]
+    fn fx_options_android_no_package() {
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("androidAvtivity".into(), json!("foo"));
+
+        let opts = make_options(firefox_opts).expect("valid firefox options");
+        assert_eq!(opts.android, None);
+    }
+
+    #[test]
+    fn fx_options_android_package_valid_value() {
+        for value in ["foo.bar", "foo.bar.cheese.is.good", "Foo.Bar_9"].iter() {
+            let mut firefox_opts = Capabilities::new();
+            firefox_opts.insert("androidPackage".into(), json!(value));
+
+            let opts = make_options(firefox_opts).expect("valid firefox options");
+            assert_eq!(
+                opts.android,
+                Some(AndroidOptions::new(
+                    value.to_string(),
+                    AndroidStorageInput::Auto
+                ))
+            );
+        }
+    }
+
+    #[test]
+    fn fx_options_android_package_invalid_type() {
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("androidPackage".into(), json!(42));
+
+        make_options(firefox_opts).expect_err("invalid firefox options");
+    }
+
+    #[test]
+    fn fx_options_android_package_invalid_value() {
+        for value in ["../foo", "\\foo\n", "foo", "_foo", "0foo"].iter() {
+            let mut firefox_opts = Capabilities::new();
+            firefox_opts.insert("androidPackage".into(), json!(value));
+            make_options(firefox_opts).expect_err("invalid firefox options");
+        }
+    }
+
+    #[test]
+    fn fx_options_android_activity_valid_value() {
+        for value in ["cheese", "Cheese_9"].iter() {
+            let mut firefox_opts = Capabilities::new();
+            firefox_opts.insert("androidPackage".into(), json!("foo.bar"));
+            firefox_opts.insert("androidActivity".into(), json!(value));
+
+            let opts = make_options(firefox_opts).expect("valid firefox options");
+            let android_opts = AndroidOptions {
+                package: "foo.bar".to_owned(),
+                activity: Some(value.to_string()),
+                ..Default::default()
+            };
+            assert_eq!(opts.android, Some(android_opts));
+        }
+    }
+
+    #[test]
+    fn fx_options_android_activity_invalid_type() {
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("androidPackage".into(), json!("foo.bar"));
+        firefox_opts.insert("androidActivity".into(), json!(42));
+
+        make_options(firefox_opts).expect_err("invalid firefox options");
+    }
+
+    #[test]
+    fn fx_options_android_activity_invalid_value() {
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("androidPackage".into(), json!("foo.bar"));
+        firefox_opts.insert("androidActivity".into(), json!("foo.bar/cheese"));
+
+        make_options(firefox_opts).expect_err("invalid firefox options");
+    }
+
+    #[test]
+    fn fx_options_android_device_serial() {
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("androidPackage".into(), json!("foo.bar"));
+        firefox_opts.insert("androidDeviceSerial".into(), json!("cheese"));
+
+        let opts = make_options(firefox_opts).expect("valid firefox options");
+        let android_opts = AndroidOptions {
+            package: "foo.bar".to_owned(),
+            device_serial: Some("cheese".to_owned()),
+            ..Default::default()
+        };
+        assert_eq!(opts.android, Some(android_opts));
+    }
+
+    #[test]
+    fn fx_options_android_serial_invalid() {
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("androidPackage".into(), json!("foo.bar"));
+        firefox_opts.insert("androidDeviceSerial".into(), json!(42));
+
+        make_options(firefox_opts).expect_err("invalid firefox options");
+    }
+
+    #[test]
+    fn fx_options_android_intent_arguments() {
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("androidPackage".into(), json!("foo.bar"));
+        firefox_opts.insert("androidIntentArguments".into(), json!(["lorem", "ipsum"]));
+
+        let opts = make_options(firefox_opts).expect("valid firefox options");
+        let android_opts = AndroidOptions {
+            package: "foo.bar".to_owned(),
+            intent_arguments: Some(vec!["lorem".to_owned(), "ipsum".to_owned()]),
+            ..Default::default()
+        };
+        assert_eq!(opts.android, Some(android_opts));
+    }
+
+    #[test]
+    fn fx_options_android_intent_arguments_no_array() {
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("androidPackage".into(), json!("foo.bar"));
+        firefox_opts.insert("androidIntentArguments".into(), json!(42));
+
+        make_options(firefox_opts).expect_err("invalid firefox options");
+    }
+
+    #[test]
+    fn fx_options_android_intent_arguments_invalid_value() {
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("androidPackage".into(), json!("foo.bar"));
+        firefox_opts.insert("androidIntentArguments".into(), json!(["lorem", 42]));
+
+        make_options(firefox_opts).expect_err("invalid firefox options");
+    }
+
+    #[test]
+    fn fx_options_env() {
+        let mut env: Map<String, Value> = Map::new();
+        env.insert("TEST_KEY_A".into(), Value::String("test_value_a".into()));
+        env.insert("TEST_KEY_B".into(), Value::String("test_value_b".into()));
+
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("env".into(), env.into());
+
+        let mut opts = make_options(firefox_opts).expect("valid firefox options");
+        for sorted in opts.env.iter_mut() {
+            sorted.sort()
+        }
+        assert_eq!(
+            opts.env,
+            Some(vec![
+                ("TEST_KEY_A".into(), "test_value_a".into()),
+                ("TEST_KEY_B".into(), "test_value_b".into()),
+            ])
+        );
+    }
+
+    #[test]
+    fn fx_options_env_invalid_container() {
+        let env = Value::Number(1.into());
+
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("env".into(), env.into());
+
+        make_options(firefox_opts).expect_err("invalid firefox options");
+    }
+
+    #[test]
+    fn fx_options_env_invalid_value() {
+        let mut env: Map<String, Value> = Map::new();
+        env.insert("TEST_KEY".into(), Value::Number(1.into()));
+
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("env".into(), env.into());
+
+        make_options(firefox_opts).expect_err("invalid firefox options");
+    }
+
+    #[test]
+    fn test_profile() {
+        let encoded_profile = example_profile();
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("profile".into(), encoded_profile);
+
+        let opts = make_options(firefox_opts).expect("valid firefox options");
+        let mut profile = opts.profile.expect("valid firefox profile");
+        let prefs = profile.user_prefs().expect("valid preferences");
+
+        println!("{:#?}", prefs.prefs);
+
+        assert_eq!(
+            prefs.get("startup.homepage_welcome_url"),
+            Some(&Pref::new("data:text/html,PASS"))
+        );
+    }
+
+    #[test]
+    fn test_prefs() {
+        let encoded_profile = example_profile();
+        let mut prefs: Map<String, Value> = Map::new();
+        prefs.insert(
+            "browser.display.background_color".into(),
+            Value::String("#00ff00".into()),
+        );
+
+        let mut firefox_opts = Capabilities::new();
+        firefox_opts.insert("profile".into(), encoded_profile);
+        firefox_opts.insert("prefs".into(), Value::Object(prefs));
+
+        let opts = make_options(firefox_opts).expect("valid profile and prefs");
+        let mut profile = opts.profile.expect("valid firefox profile");
+
+        let handler = MarionetteHandler::new(Default::default());
+        handler
+            .set_prefs(2828, &mut profile, true, opts.prefs)
+            .expect("set preferences");
+
+        let prefs_set = profile.user_prefs().expect("valid user preferences");
+        println!("{:#?}", prefs_set.prefs);
+
+        assert_eq!(
+            prefs_set.get("startup.homepage_welcome_url"),
+            Some(&Pref::new("data:text/html,PASS"))
+        );
+        assert_eq!(
+            prefs_set.get("browser.display.background_color"),
+            Some(&Pref::new("#00ff00"))
+        );
+        assert_eq!(prefs_set.get("marionette.port"), Some(&Pref::new(2828)));
+    }
+}
diff --git a/testing/geckodriver/src/command.rs b/testing/geckodriver/src/command.rs
new file mode 100644
index 0000000000..f5bc27ad81
--- /dev/null
+++ b/testing/geckodriver/src/command.rs
@@ -0,0 +1,342 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use crate::logging;
+use base64;
+use hyper::Method;
+use serde::de::{self, Deserialize, Deserializer};
+use serde_json::{self, Value};
+use std::env;
+use std::fs::File;
+use std::io::prelude::*;
+use uuid::Uuid;
+use webdriver::command::{WebDriverCommand, WebDriverExtensionCommand};
+use webdriver::error::WebDriverResult;
+use webdriver::httpapi::WebDriverExtensionRoute;
+use webdriver::Parameters;
+
+pub const CHROME_ELEMENT_KEY: &str = "chromeelement-9fc5-4b51-a3c8-01716eedeb04";
+
+pub fn extension_routes() -> Vec<(Method, &'static str, GeckoExtensionRoute)> {
+    return vec![
+        (
+            Method::GET,
+            "/session/{sessionId}/moz/context",
+            GeckoExtensionRoute::GetContext,
+        ),
+        (
+            Method::POST,
+            "/session/{sessionId}/moz/context",
+            GeckoExtensionRoute::SetContext,
+        ),
+        (
+            Method::POST,
+            "/session/{sessionId}/moz/addon/install",
+            GeckoExtensionRoute::InstallAddon,
+        ),
+        (
+            Method::POST,
+            "/session/{sessionId}/moz/addon/uninstall",
+            GeckoExtensionRoute::UninstallAddon,
+        ),
+        (
+            Method::GET,
+            "/session/{sessionId}/moz/screenshot/full",
+            GeckoExtensionRoute::TakeFullScreenshot,
+        ),
+    ];
+}
+
+#[derive(Clone, PartialEq)]
+pub enum GeckoExtensionRoute {
+    GetContext,
+    SetContext,
+    InstallAddon,
+    UninstallAddon,
+    TakeFullScreenshot,
+}
+
+impl WebDriverExtensionRoute for GeckoExtensionRoute {
+    type Command = GeckoExtensionCommand;
+
+    fn command(
+        &self,
+        _params: &Parameters,
+        body_data: &Value,
+    ) -> WebDriverResult<WebDriverCommand<GeckoExtensionCommand>> {
+        use self::GeckoExtensionRoute::*;
+
+        let command = match *self {
+            GetContext => GeckoExtensionCommand::GetContext,
+            SetContext => {
+                GeckoExtensionCommand::SetContext(serde_json::from_value(body_data.clone())?)
+            }
+            InstallAddon => {
+                GeckoExtensionCommand::InstallAddon(serde_json::from_value(body_data.clone())?)
+            }
+            UninstallAddon => {
+                GeckoExtensionCommand::UninstallAddon(serde_json::from_value(body_data.clone())?)
+            }
+            TakeFullScreenshot => GeckoExtensionCommand::TakeFullScreenshot,
+        };
+
+        Ok(WebDriverCommand::Extension(command))
+    }
+}
+
+#[derive(Clone)]
+pub enum GeckoExtensionCommand {
+    GetContext,
+    SetContext(GeckoContextParameters),
+    InstallAddon(AddonInstallParameters),
+    UninstallAddon(AddonUninstallParameters),
+    TakeFullScreenshot,
+}
+
+impl WebDriverExtensionCommand for GeckoExtensionCommand {
+    fn parameters_json(&self) -> Option<Value> {
+        use self::GeckoExtensionCommand::*;
+        match self {
+            GetContext => None,
+            InstallAddon(x) => Some(serde_json::to_value(x).unwrap()),
+            SetContext(x) => Some(serde_json::to_value(x).unwrap()),
+            UninstallAddon(x) => Some(serde_json::to_value(x).unwrap()),
+            TakeFullScreenshot => None,
+        }
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize)]
+pub struct AddonInstallParameters {
+    pub path: String,
+    pub temporary: Option<bool>,
+}
+
+impl<'de> Deserialize<'de> for AddonInstallParameters {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        #[derive(Debug, Deserialize)]
+        #[serde(deny_unknown_fields)]
+        struct Base64 {
+            addon: String,
+            temporary: Option<bool>,
+        };
+
+        #[derive(Debug, Deserialize)]
+        #[serde(deny_unknown_fields)]
+        struct Path {
+            path: String,
+            temporary: Option<bool>,
+        };
+
+        #[derive(Debug, Deserialize)]
+        #[serde(untagged)]
+        enum Helper {
+            Base64(Base64),
+            Path(Path),
+        };
+
+        let params = match Helper::deserialize(deserializer)? {
+            Helper::Path(ref mut data) => AddonInstallParameters {
+                path: data.path.clone(),
+                temporary: data.temporary,
+            },
+            Helper::Base64(ref mut data) => {
+                let content = base64::decode(&data.addon).map_err(de::Error::custom)?;
+
+                let path = env::temp_dir()
+                    .as_path()
+                    .join(format!("addon-{}.xpi", Uuid::new_v4()));
+                let mut xpi_file = File::create(&path).map_err(de::Error::custom)?;
+                xpi_file
+                    .write(content.as_slice())
+                    .map_err(de::Error::custom)?;
+
+                let path = match path.to_str() {
+                    Some(path) => path.to_string(),
+                    None => return Err(de::Error::custom("could not write addon to file")),
+                };
+
+                AddonInstallParameters {
+                    path,
+                    temporary: data.temporary,
+                }
+            }
+        };
+
+        Ok(params)
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct AddonUninstallParameters {
+    pub id: String,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum GeckoContext {
+    Content,
+    Chrome,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct GeckoContextParameters {
+    pub context: GeckoContext,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct XblLocatorParameters {
+    pub name: String,
+    pub value: String,
+}
+
+#[derive(Default, Debug, PartialEq)]
+pub struct LogOptions {
+    pub level: Option<logging::Level>,
+}
+
+#[cfg(test)]
+mod tests {
+    use serde_json::json;
+
+    use super::*;
+    use crate::test::assert_de;
+
+    #[test]
+    fn test_json_addon_install_parameters_invalid() {
+        assert!(serde_json::from_str::<AddonInstallParameters>("").is_err());
+        assert!(serde_json::from_value::<AddonInstallParameters>(json!(null)).is_err());
+        assert!(serde_json::from_value::<AddonInstallParameters>(json!({})).is_err());
+    }
+
+    #[test]
+    fn test_json_addon_install_parameters_with_path_and_temporary() {
+        let params = AddonInstallParameters {
+            path: "/path/to.xpi".to_string(),
+            temporary: Some(true),
+        };
+        assert_de(&params, json!({"path": "/path/to.xpi", "temporary": true}));
+    }
+
+    #[test]
+    fn test_json_addon_install_parameters_with_path() {
+        let params = AddonInstallParameters {
+            path: "/path/to.xpi".to_string(),
+            temporary: None,
+        };
+        assert_de(&params, json!({"path": "/path/to.xpi"}));
+    }
+
+    #[test]
+    fn test_json_addon_install_parameters_with_path_invalid_type() {
+        let json = json!({"path": true, "temporary": true});
+        assert!(serde_json::from_value::<AddonInstallParameters>(json).is_err());
+    }
+
+    #[test]
+    fn test_json_addon_install_parameters_with_path_and_temporary_invalid_type() {
+        let json = json!({"path": "/path/to.xpi", "temporary": "foo"});
+        assert!(serde_json::from_value::<AddonInstallParameters>(json).is_err());
+    }
+
+    #[test]
+    fn test_json_addon_install_parameters_with_addon() {
+        let json = json!({"addon": "aGVsbG8=", "temporary": true});
+        let data = serde_json::from_value::<AddonInstallParameters>(json).unwrap();
+
+        assert_eq!(data.temporary, Some(true));
+        let mut file = File::open(data.path).unwrap();
+        let mut contents = String::new();
+        file.read_to_string(&mut contents).unwrap();
+        assert_eq!(contents, "hello");
+    }
+
+    #[test]
+    fn test_json_addon_install_parameters_with_addon_only() {
+        let json = json!({"addon": "aGVsbG8="});
+        let data = serde_json::from_value::<AddonInstallParameters>(json).unwrap();
+
+        assert_eq!(data.temporary, None);
+        let mut file = File::open(data.path).unwrap();
+        let mut contents = String::new();
+        file.read_to_string(&mut contents).unwrap();
+        assert_eq!(contents, "hello");
+    }
+
+    #[test]
+    fn test_json_addon_install_parameters_with_addon_invalid_type() {
+        let json = json!({"addon": true, "temporary": true});
+        assert!(serde_json::from_value::<AddonInstallParameters>(json).is_err());
+    }
+
+    #[test]
+    fn test_json_addon_install_parameters_with_addon_and_temporary_invalid_type() {
+        let json = json!({"addon": "aGVsbG8=", "temporary": "foo"});
+        assert!(serde_json::from_value::<AddonInstallParameters>(json).is_err());
+    }
+
+    #[test]
+    fn test_json_install_parameters_with_temporary_only() {
+        let json = json!({"temporary": true});
+        assert!(serde_json::from_value::<AddonInstallParameters>(json).is_err());
+    }
+
+    #[test]
+    fn test_json_addon_install_parameters_with_both_path_and_addon() {
+        let json = json!({
+            "path": "/path/to.xpi",
+            "addon": "aGVsbG8=",
+            "temporary": true,
+        });
+        assert!(serde_json::from_value::<AddonInstallParameters>(json).is_err());
+    }
+
+    #[test]
+    fn test_json_addon_uninstall_parameters_invalid() {
+        assert!(serde_json::from_str::<AddonUninstallParameters>("").is_err());
+        assert!(serde_json::from_value::<AddonUninstallParameters>(json!(null)).is_err());
+        assert!(serde_json::from_value::<AddonUninstallParameters>(json!({})).is_err());
+    }
+
+    #[test]
+    fn test_json_addon_uninstall_parameters() {
+        let params = AddonUninstallParameters {
+            id: "foo".to_string(),
+        };
+        assert_de(&params, json!({"id": "foo"}));
+    }
+
+    #[test]
+    fn test_json_addon_uninstall_parameters_id_invalid_type() {
+        let json = json!({"id": true});
+        assert!(serde_json::from_value::<AddonUninstallParameters>(json).is_err());
+    }
+
+    #[test]
+    fn test_json_gecko_context_parameters_content() {
+        let params = GeckoContextParameters {
+            context: GeckoContext::Content,
+        };
+        assert_de(&params, json!({"context": "content"}));
+    }
+
+    #[test]
+    fn test_json_gecko_context_parameters_chrome() {
+        let params = GeckoContextParameters {
+            context: GeckoContext::Chrome,
+        };
+        assert_de(&params, json!({"context": "chrome"}));
+    }
+
+    #[test]
+    fn test_json_gecko_context_parameters_context_invalid() {
+        type P = GeckoContextParameters;
+        assert!(serde_json::from_value::<P>(json!({})).is_err());
+        assert!(serde_json::from_value::<P>(json!({ "context": null })).is_err());
+        assert!(serde_json::from_value::<P>(json!({"context": "foo"})).is_err());
+    }
+}
diff --git a/testing/geckodriver/src/logging.rs b/testing/geckodriver/src/logging.rs
new file mode 100644
index 0000000000..7721bb7770
--- /dev/null
+++ b/testing/geckodriver/src/logging.rs
@@ -0,0 +1,351 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Gecko-esque logger implementation for the [`log`] crate.
+//!
+//! The [`log`] crate provides a single logging API that abstracts over the
+//! actual logging implementation.  This module uses the logging API
+//! to provide a log implementation that shares many aesthetical traits with
+//! [Log.jsm] from Gecko.
+//!
+//! Using the [`error!`], [`warn!`], [`info!`], [`debug!`], and
+//! [`trace!`] macros from `log` will output a timestamp field, followed by the
+//! log level, and then the message.  The fields are separated by a tab
+//! character, making the output suitable for further text processing with
+//! `awk(1)`.
+//!
+//! This module shares the same API as `log`, except it provides additional
+//! entry functions [`init`] and [`init_with_level`] and additional log levels
+//! `Level::Fatal` and `Level::Config`.  Converting these into the
+//! [`log::Level`] is lossy so that `Level::Fatal` becomes `log::Level::Error`
+//! and `Level::Config` becomes `log::Level::Debug`.
+//!
+//! [`log`]: https://docs.rs/log/newest/log/
+//! [Log.jsm]: https://developer.mozilla.org/en/docs/Mozilla/JavaScript_code_modules/Log.jsm
+//! [`error!`]: https://docs.rs/log/newest/log/macro.error.html
+//! [`warn!`]: https://docs.rs/log/newest/log/macro.warn.html
+//! [`info!`]: https://docs.rs/log/newest/log/macro.info.html
+//! [`debug!`]: https://docs.rs/log/newest/log/macro.debug.html
+//! [`trace!`]: https://docs.rs/log/newest/log/macro.trace.html
+//! [`init`]: fn.init.html
+//! [`init_with_level`]: fn.init_with_level.html
+
+use std::fmt;
+use std::io;
+use std::io::Write;
+use std::str;
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+use chrono;
+use log;
+use mozprofile::preferences::Pref;
+
+static MAX_LOG_LEVEL: AtomicUsize = AtomicUsize::new(0);
+const LOGGED_TARGETS: &[&str] = &[
+    "geckodriver",
+    "mozdevice",
+    "mozprofile",
+    "mozrunner",
+    "mozversion",
+    "webdriver",
+];
+
+/// Logger levels from [Log.jsm].
+///
+/// [Log.jsm]: https://developer.mozilla.org/en/docs/Mozilla/JavaScript_code_modules/Log.jsm
+#[repr(usize)]
+#[derive(Clone, Copy, Eq, Debug, Hash, PartialEq)]
+pub enum Level {
+    Fatal = 70,
+    Error = 60,
+    Warn = 50,
+    Info = 40,
+    Config = 30,
+    Debug = 20,
+    Trace = 10,
+}
+
+impl From<usize> for Level {
+    fn from(n: usize) -> Level {
+        use self::Level::*;
+        match n {
+            70 => Fatal,
+            60 => Error,
+            50 => Warn,
+            40 => Info,
+            30 => Config,
+            20 => Debug,
+            10 => Trace,
+            _ => Info,
+        }
+    }
+}
+
+impl fmt::Display for Level {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use self::Level::*;
+        let s = match *self {
+            Fatal => "FATAL",
+            Error => "ERROR",
+            Warn => "WARN",
+            Info => "INFO",
+            Config => "CONFIG",
+            Debug => "DEBUG",
+            Trace => "TRACE",
+        };
+        write!(f, "{}", s)
+    }
+}
+
+impl str::FromStr for Level {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Level, ()> {
+        use self::Level::*;
+        match s.to_lowercase().as_ref() {
+            "fatal" => Ok(Fatal),
+            "error" => Ok(Error),
+            "warn" => Ok(Warn),
+            "info" => Ok(Info),
+            "config" => Ok(Config),
+            "debug" => Ok(Debug),
+            "trace" => Ok(Trace),
+            _ => Err(()),
+        }
+    }
+}
+
+impl Into<log::Level> for Level {
+    fn into(self) -> log::Level {
+        use self::Level::*;
+        match self {
+            Fatal | Error => log::Level::Error,
+            Warn => log::Level::Warn,
+            Info => log::Level::Info,
+            Config | Debug => log::Level::Debug,
+            Trace => log::Level::Trace,
+        }
+    }
+}
+
+impl Into<Pref> for Level {
+    fn into(self) -> Pref {
+        use self::Level::*;
+        Pref::new(match self {
+            Fatal => "Fatal",
+            Error => "Error",
+            Warn => "Warn",
+            Info => "Info",
+            Config => "Config",
+            Debug => "Debug",
+            Trace => "Trace",
+        })
+    }
+}
+
+impl From<log::Level> for Level {
+    fn from(log_level: log::Level) -> Level {
+        use log::Level::*;
+        match log_level {
+            Error => Level::Error,
+            Warn => Level::Warn,
+            Info => Level::Info,
+            Debug => Level::Debug,
+            Trace => Level::Trace,
+        }
+    }
+}
+
+struct Logger;
+
+impl log::Log for Logger {
+    fn enabled(&self, meta: &log::Metadata) -> bool {
+        LOGGED_TARGETS.iter().any(|&x| meta.target().starts_with(x))
+            && meta.level() <= log::max_level()
+    }
+
+    fn log(&self, record: &log::Record) {
+        if self.enabled(record.metadata()) {
+            let ts = format_ts(chrono::Local::now());
+            println!(
+                "{}\t{}\t{}\t{}",
+                ts,
+                record.target(),
+                record.level(),
+                record.args()
+            );
+        }
+    }
+
+    fn flush(&self) {
+        io::stdout().flush().unwrap();
+    }
+}
+
+/// Initialises the logging subsystem with the default log level.
+pub fn init() -> Result<(), log::SetLoggerError> {
+    init_with_level(Level::Info)
+}
+
+/// Initialises the logging subsystem.
+pub fn init_with_level(level: Level) -> Result<(), log::SetLoggerError> {
+    let logger = Logger {};
+    set_max_level(level);
+    log::set_boxed_logger(Box::new(logger))?;
+    Ok(())
+}
+
+/// Returns the current maximum log level.
+pub fn max_level() -> Level {
+    MAX_LOG_LEVEL.load(Ordering::Relaxed).into()
+}
+
+/// Sets the global maximum log level.
+pub fn set_max_level(level: Level) {
+    MAX_LOG_LEVEL.store(level as usize, Ordering::SeqCst);
+
+    let slevel: log::Level = level.into();
+    log::set_max_level(slevel.to_level_filter())
+}
+
+/// Produces a 13-digit Unix Epoch timestamp similar to Gecko.
+fn format_ts(ts: chrono::DateTime<chrono::Local>) -> String {
+    format!("{}{:03}", ts.timestamp(), ts.timestamp_subsec_millis())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{format_ts, init_with_level, max_level, set_max_level, Level};
+
+    use std::str::FromStr;
+    use std::sync::Mutex;
+
+    use chrono;
+    use log;
+    use mozprofile::preferences::{Pref, PrefValue};
+
+    lazy_static! {
+        static ref LEVEL_MUTEX: Mutex<()> = Mutex::new(());
+    }
+
+    #[test]
+    fn test_level_repr() {
+        assert_eq!(Level::Fatal as usize, 70);
+        assert_eq!(Level::Error as usize, 60);
+        assert_eq!(Level::Warn as usize, 50);
+        assert_eq!(Level::Info as usize, 40);
+        assert_eq!(Level::Config as usize, 30);
+        assert_eq!(Level::Debug as usize, 20);
+        assert_eq!(Level::Trace as usize, 10);
+    }
+
+    #[test]
+    fn test_level_eq() {
+        assert_eq!(Level::Fatal, Level::Fatal);
+        assert_eq!(Level::Error, Level::Error);
+        assert_eq!(Level::Warn, Level::Warn);
+        assert_eq!(Level::Info, Level::Info);
+        assert_eq!(Level::Config, Level::Config);
+        assert_eq!(Level::Debug, Level::Debug);
+        assert_eq!(Level::Trace, Level::Trace);
+    }
+
+    #[test]
+    fn test_level_from_log() {
+        assert_eq!(Level::from(log::Level::Error), Level::Error);
+        assert_eq!(Level::from(log::Level::Warn), Level::Warn);
+        assert_eq!(Level::from(log::Level::Info), Level::Info);
+        assert_eq!(Level::from(log::Level::Debug), Level::Debug);
+        assert_eq!(Level::from(log::Level::Trace), Level::Trace);
+    }
+
+    #[test]
+    fn test_level_into_log() {
+        assert_eq!(Into::<log::Level>::into(Level::Fatal), log::Level::Error);
+        assert_eq!(Into::<log::Level>::into(Level::Error), log::Level::Error);
+        assert_eq!(Into::<log::Level>::into(Level::Warn), log::Level::Warn);
+        assert_eq!(Into::<log::Level>::into(Level::Info), log::Level::Info);
+        assert_eq!(Into::<log::Level>::into(Level::Config), log::Level::Debug);
+        assert_eq!(Into::<log::Level>::into(Level::Debug), log::Level::Debug);
+        assert_eq!(Into::<log::Level>::into(Level::Trace), log::Level::Trace);
+    }
+
+    #[test]
+    fn test_level_into_pref() {
+        let tests = [
+            (Level::Fatal, "Fatal"),
+            (Level::Error, "Error"),
+            (Level::Warn, "Warn"),
+            (Level::Info, "Info"),
+            (Level::Config, "Config"),
+            (Level::Debug, "Debug"),
+            (Level::Trace, "Trace"),
+        ];
+
+        for &(lvl, s) in tests.iter() {
+            let expected = Pref {
+                value: PrefValue::String(s.to_string()),
+                sticky: false,
+            };
+            assert_eq!(Into::<Pref>::into(lvl), expected);
+        }
+    }
+
+    #[test]
+    fn test_level_from_str() {
+        assert_eq!(Level::from_str("fatal"), Ok(Level::Fatal));
+        assert_eq!(Level::from_str("error"), Ok(Level::Error));
+        assert_eq!(Level::from_str("warn"), Ok(Level::Warn));
+        assert_eq!(Level::from_str("info"), Ok(Level::Info));
+        assert_eq!(Level::from_str("config"), Ok(Level::Config));
+        assert_eq!(Level::from_str("debug"), Ok(Level::Debug));
+        assert_eq!(Level::from_str("trace"), Ok(Level::Trace));
+
+        assert_eq!(Level::from_str("INFO"), Ok(Level::Info));
+
+        assert!(Level::from_str("foo").is_err());
+    }
+
+    #[test]
+    fn test_level_to_str() {
+        assert_eq!(Level::Fatal.to_string(), "FATAL");
+        assert_eq!(Level::Error.to_string(), "ERROR");
+        assert_eq!(Level::Warn.to_string(), "WARN");
+        assert_eq!(Level::Info.to_string(), "INFO");
+        assert_eq!(Level::Config.to_string(), "CONFIG");
+        assert_eq!(Level::Debug.to_string(), "DEBUG");
+        assert_eq!(Level::Trace.to_string(), "TRACE");
+    }
+
+    #[test]
+    fn test_max_level() {
+        let _guard = LEVEL_MUTEX.lock();
+        set_max_level(Level::Info);
+        assert_eq!(max_level(), Level::Info);
+    }
+
+    #[test]
+    fn test_set_max_level() {
+        let _guard = LEVEL_MUTEX.lock();
+        set_max_level(Level::Error);
+        assert_eq!(max_level(), Level::Error);
+        set_max_level(Level::Fatal);
+        assert_eq!(max_level(), Level::Fatal);
+    }
+
+    #[test]
+    fn test_init_with_level() {
+        let _guard = LEVEL_MUTEX.lock();
+        init_with_level(Level::Debug).unwrap();
+        assert_eq!(max_level(), Level::Debug);
+        assert!(init_with_level(Level::Warn).is_err());
+    }
+
+    #[test]
+    fn test_format_ts() {
+        let ts = chrono::Local::now();
+        let s = format_ts(ts);
+        assert_eq!(s.len(), 13);
+    }
+}
diff --git a/testing/geckodriver/src/main.rs b/testing/geckodriver/src/main.rs
new file mode 100644
index 0000000000..4dd6c668d9
--- /dev/null
+++ b/testing/geckodriver/src/main.rs
@@ -0,0 +1,351 @@
+#![forbid(unsafe_code)]
+
+extern crate chrono;
+#[macro_use]
+extern crate clap;
+#[macro_use]
+extern crate lazy_static;
+extern crate hyper;
+extern crate marionette as marionette_rs;
+extern crate mozdevice;
+extern crate mozprofile;
+extern crate mozrunner;
+extern crate mozversion;
+extern crate regex;
+extern crate serde;
+#[macro_use]
+extern crate serde_derive;
+extern crate serde_json;
+extern crate serde_yaml;
+extern crate uuid;
+extern crate webdriver;
+extern crate zip;
+
+#[macro_use]
+extern crate log;
+
+use std::env;
+use std::fmt;
+use std::io;
+use std::net::{IpAddr, SocketAddr};
+use std::path::PathBuf;
+use std::result;
+use std::str::FromStr;
+
+use clap::{App, Arg};
+
+macro_rules! try_opt {
+    ($expr:expr, $err_type:expr, $err_msg:expr) => {{
+        match $expr {
+            Some(x) => x,
+            None => return Err(WebDriverError::new($err_type, $err_msg)),
+        }
+    }};
+}
+
+mod android;
+mod build;
+mod capabilities;
+mod command;
+mod logging;
+mod marionette;
+mod prefs;
+
+#[cfg(test)]
+pub mod test;
+
+use crate::command::extension_routes;
+use crate::logging::Level;
+use crate::marionette::{MarionetteHandler, MarionetteSettings};
+use mozdevice::AndroidStorageInput;
+
+const EXIT_SUCCESS: i32 = 0;
+const EXIT_USAGE: i32 = 64;
+const EXIT_UNAVAILABLE: i32 = 69;
+
+enum FatalError {
+    Parsing(clap::Error),
+    Usage(String),
+    Server(io::Error),
+}
+
+impl FatalError {
+    fn exit_code(&self) -> i32 {
+        use FatalError::*;
+        match *self {
+            Parsing(_) | Usage(_) => EXIT_USAGE,
+            Server(_) => EXIT_UNAVAILABLE,
+        }
+    }
+
+    fn help_included(&self) -> bool {
+        match *self {
+            FatalError::Parsing(_) => true,
+            _ => false,
+        }
+    }
+}
+
+impl From<clap::Error> for FatalError {
+    fn from(err: clap::Error) -> FatalError {
+        FatalError::Parsing(err)
+    }
+}
+
+impl From<io::Error> for FatalError {
+    fn from(err: io::Error) -> FatalError {
+        FatalError::Server(err)
+    }
+}
+
+// harmonise error message from clap to avoid duplicate "error:" prefix
+impl fmt::Display for FatalError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use FatalError::*;
+        let s = match *self {
+            Parsing(ref err) => err.to_string(),
+            Usage(ref s) => format!("error: {}", s),
+            Server(ref err) => format!("error: {}", err.to_string()),
+        };
+        write!(f, "{}", s)
+    }
+}
+
+macro_rules! usage {
+    ($msg:expr) => {
+        return Err(FatalError::Usage($msg.to_string()));
+    };
+
+    ($fmt:expr, $($arg:tt)+) => {
+        return Err(FatalError::Usage(format!($fmt, $($arg)+)));
+    };
+}
+
+type ProgramResult<T> = result::Result<T, FatalError>;
+
+enum Operation {
+    Help,
+    Version,
+    Server {
+        log_level: Option<Level>,
+        address: SocketAddr,
+        settings: MarionetteSettings,
+    },
+}
+
+fn parse_args(app: &mut App) -> ProgramResult<Operation> {
+    let matches = app.get_matches_from_safe_borrow(env::args())?;
+
+    let log_level = if matches.is_present("log_level") {
+        Level::from_str(matches.value_of("log_level").unwrap()).ok()
+    } else {
+        Some(match matches.occurrences_of("verbosity") {
+            0 => Level::Info,
+            1 => Level::Debug,
+            _ => Level::Trace,
+        })
+    };
+
+    let host = matches.value_of("webdriver_host").unwrap();
+    let port = {
+        let s = matches.value_of("webdriver_port").unwrap();
+        match u16::from_str(s) {
+            Ok(n) => n,
+            Err(e) => usage!("invalid --port: {}: {}", e, s),
+        }
+    };
+    let address = match IpAddr::from_str(host) {
+        Ok(addr) => SocketAddr::new(addr, port),
+        Err(e) => usage!("{}: {}:{}", e, host, port),
+    };
+
+    let android_storage = value_t!(matches, "android_storage", AndroidStorageInput)?;
+
+    let binary = matches.value_of("binary").map(PathBuf::from);
+
+    let marionette_host = matches.value_of("marionette_host").unwrap();
+    let marionette_port = match matches.value_of("marionette_port") {
+        Some(s) => match u16::from_str(s) {
+            Ok(n) => Some(n),
+            Err(e) => usage!("invalid --marionette-port: {}", e),
+        },
+        None => None,
+    };
+
+    let op = if matches.is_present("help") {
+        Operation::Help
+    } else if matches.is_present("version") {
+        Operation::Version
+    } else {
+        let settings = MarionetteSettings {
+            host: marionette_host.to_string(),
+            port: marionette_port,
+            binary,
+            connect_existing: matches.is_present("connect_existing"),
+            jsdebugger: matches.is_present("jsdebugger"),
+            android_storage,
+        };
+        Operation::Server {
+            log_level,
+            address,
+            settings,
+        }
+    };
+
+    Ok(op)
+}
+
+fn inner_main(app: &mut App) -> ProgramResult<()> {
+    match parse_args(app)? {
+        Operation::Help => print_help(app),
+        Operation::Version => print_version(),
+
+        Operation::Server {
+            log_level,
+            address,
+            settings,
+        } => {
+            if let Some(ref level) = log_level {
+                logging::init_with_level(*level).unwrap();
+            } else {
+                logging::init().unwrap();
+            }
+
+            let handler = MarionetteHandler::new(settings);
+            let listening = webdriver::server::start(address, handler, extension_routes())?;
+            info!("Listening on {}", listening.socket);
+        }
+    }
+
+    Ok(())
+}
+
+fn main() {
+    use std::process::exit;
+
+    let mut app = make_app();
+
+    // use std::process:Termination when it graduates
+    exit(match inner_main(&mut app) {
+        Ok(_) => EXIT_SUCCESS,
+
+        Err(e) => {
+            eprintln!("{}: {}", get_program_name(), e);
+            if !e.help_included() {
+                print_help(&mut app);
+            }
+
+            e.exit_code()
+        }
+    });
+}
+
+fn make_app<'a, 'b>() -> App<'a, 'b> {
+    App::new(format!("geckodriver {}", build::build_info()))
+        .about("WebDriver implementation for Firefox")
+        .arg(
+            Arg::with_name("webdriver_host")
+                .long("host")
+                .takes_value(true)
+                .value_name("HOST")
+                .default_value("127.0.0.1")
+                .help("Host IP to use for WebDriver server"),
+        )
+        .arg(
+            Arg::with_name("webdriver_port")
+                .short("p")
+                .long("port")
+                .takes_value(true)
+                .value_name("PORT")
+                .default_value("4444")
+                .help("Port to use for WebDriver server"),
+        )
+        .arg(
+            Arg::with_name("binary")
+                .short("b")
+                .long("binary")
+                .takes_value(true)
+                .value_name("BINARY")
+                .help("Path to the Firefox binary"),
+        )
+        .arg(
+            Arg::with_name("marionette_host")
+                .long("marionette-host")
+                .takes_value(true)
+                .value_name("HOST")
+                .default_value("127.0.0.1")
+                .help("Host to use to connect to Gecko"),
+        )
+        .arg(
+            Arg::with_name("marionette_port")
+                .long("marionette-port")
+                .takes_value(true)
+                .value_name("PORT")
+                .help("Port to use to connect to Gecko [default: system-allocated port]"),
+        )
+        .arg(
+            Arg::with_name("connect_existing")
+                .long("connect-existing")
+                .requires("marionette_port")
+                .help("Connect to an existing Firefox instance"),
+        )
+        .arg(
+            Arg::with_name("jsdebugger")
+                .long("jsdebugger")
+                .help("Attach browser toolbox debugger for Firefox"),
+        )
+        .arg(
+            Arg::with_name("verbosity")
+                .multiple(true)
+                .conflicts_with("log_level")
+                .short("v")
+                .help("Log level verbosity (-v for debug and -vv for trace level)"),
+        )
+        .arg(
+            Arg::with_name("log_level")
+                .long("log")
+                .takes_value(true)
+                .value_name("LEVEL")
+                .possible_values(&["fatal", "error", "warn", "info", "config", "debug", "trace"])
+                .help("Set Gecko log level"),
+        )
+        .arg(
+            Arg::with_name("help")
+                .short("h")
+                .long("help")
+                .help("Prints this message"),
+        )
+        .arg(
+            Arg::with_name("version")
+                .short("V")
+                .long("version")
+                .help("Prints version and copying information"),
+        )
+        .arg(
+            Arg::with_name("android_storage")
+                .long("android-storage")
+                .possible_values(&["auto", "app", "internal", "sdcard"])
+                .default_value("auto")
+                .value_name("ANDROID_STORAGE")
+                .help("Selects storage location to be used for test data."),
+        )
+}
+
+fn get_program_name() -> String {
+    env::args().next().unwrap()
+}
+
+fn print_help(app: &mut App) {
+    app.print_help().ok();
+    println!();
+}
+
+fn print_version() {
+    println!("geckodriver {}", build::build_info());
+    println!();
+    println!("The source code of this program is available from");
+    println!("testing/geckodriver in https://hg.mozilla.org/mozilla-central.");
+    println!();
+    println!("This program is subject to the terms of the Mozilla Public License 2.0.");
+    println!("You can obtain a copy of the license at https://mozilla.org/MPL/2.0/.");
+}
diff --git a/testing/geckodriver/src/marionette.rs b/testing/geckodriver/src/marionette.rs
new file mode 100644
index 0000000000..99a82f3a89
--- /dev/null
+++ b/testing/geckodriver/src/marionette.rs
@@ -0,0 +1,1749 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use crate::android::AndroidHandler;
+use crate::command::{
+    AddonInstallParameters, AddonUninstallParameters, GeckoContextParameters,
+    GeckoExtensionCommand, GeckoExtensionRoute, CHROME_ELEMENT_KEY,
+};
+use marionette_rs::common::{
+    Cookie as MarionetteCookie, Date as MarionetteDate, Frame as MarionetteFrame,
+    Timeouts as MarionetteTimeouts, WebElement as MarionetteWebElement, Window,
+};
+use marionette_rs::marionette::AppStatus;
+use marionette_rs::message::{Command, Message, MessageId, Request};
+use marionette_rs::webdriver::{
+    Command as MarionetteWebDriverCommand, Keys as MarionetteKeys, LegacyWebElement,
+    Locator as MarionetteLocator, NewWindow as MarionetteNewWindow,
+    PrintMargins as MarionettePrintMargins, PrintOrientation as MarionettePrintOrientation,
+    PrintPage as MarionettePrintPage, PrintParameters as MarionettePrintParameters,
+    ScreenshotOptions, Script as MarionetteScript, Selector as MarionetteSelector,
+    Url as MarionetteUrl, WindowRect as MarionetteWindowRect,
+};
+use mozdevice::AndroidStorageInput;
+use mozprofile::preferences::Pref;
+use mozprofile::profile::Profile;
+use mozrunner::runner::{FirefoxProcess, FirefoxRunner, Runner, RunnerProcess};
+use serde::de::{self, Deserialize, Deserializer};
+use serde::ser::{Serialize, Serializer};
+use serde_json::{self, Map, Value};
+use std::io::prelude::*;
+use std::io::Error as IoError;
+use std::io::ErrorKind;
+use std::io::Result as IoResult;
+use std::net::{TcpListener, TcpStream};
+use std::path::PathBuf;
+use std::sync::Mutex;
+use std::thread;
+use std::time;
+use webdriver::capabilities::CapabilitiesMatching;
+use webdriver::command::WebDriverCommand::{
+    AcceptAlert, AddCookie, CloseWindow, DeleteCookie, DeleteCookies, DeleteSession, DismissAlert,
+    ElementClear, ElementClick, ElementSendKeys, ExecuteAsyncScript, ExecuteScript, Extension,
+    FindElement, FindElementElement, FindElementElements, FindElements, FullscreenWindow, Get,
+    GetActiveElement, GetAlertText, GetCSSValue, GetCookies, GetCurrentUrl, GetElementAttribute,
+    GetElementProperty, GetElementRect, GetElementTagName, GetElementText, GetNamedCookie,
+    GetPageSource, GetTimeouts, GetTitle, GetWindowHandle, GetWindowHandles, GetWindowRect, GoBack,
+    GoForward, IsDisplayed, IsEnabled, IsSelected, MaximizeWindow, MinimizeWindow, NewSession,
+    NewWindow, PerformActions, Print, Refresh, ReleaseActions, SendAlertText, SetTimeouts,
+    SetWindowRect, Status, SwitchToFrame, SwitchToParentFrame, SwitchToWindow,
+    TakeElementScreenshot, TakeScreenshot,
+};
+use webdriver::command::{
+    ActionsParameters, AddCookieParameters, GetNamedCookieParameters, GetParameters,
+    JavascriptCommandParameters, LocatorParameters, NewSessionParameters, NewWindowParameters,
+    PrintMargins, PrintOrientation, PrintPage, PrintParameters, SendKeysParameters,
+    SwitchToFrameParameters, SwitchToWindowParameters, TimeoutsParameters, WindowRectParameters,
+};
+use webdriver::command::{WebDriverCommand, WebDriverMessage};
+use webdriver::common::{
+    Cookie, Date, FrameId, LocatorStrategy, WebElement, ELEMENT_KEY, FRAME_KEY, WINDOW_KEY,
+};
+use webdriver::error::{ErrorStatus, WebDriverError, WebDriverResult};
+use webdriver::response::{
+    CloseWindowResponse, CookieResponse, CookiesResponse, ElementRectResponse, NewSessionResponse,
+    NewWindowResponse, TimeoutsResponse, ValueResponse, WebDriverResponse, WindowRectResponse,
+};
+use webdriver::server::{Session, WebDriverHandler};
+
+use crate::build;
+use crate::capabilities::{FirefoxCapabilities, FirefoxOptions};
+use crate::logging;
+use crate::prefs;
+
+/// A running Gecko instance.
+#[derive(Debug)]
+pub enum Browser {
+    /// A local Firefox process, running on this (host) device.
+    Host(FirefoxProcess),
+
+    /// A remote instance, running on a (target) Android device.
+    Target(AndroidHandler),
+}
+
+#[derive(Debug, PartialEq, Deserialize)]
+pub struct MarionetteHandshake {
+    #[serde(rename = "marionetteProtocol")]
+    protocol: u16,
+    #[serde(rename = "applicationType")]
+    application_type: String,
+}
+
+#[derive(Default)]
+pub struct MarionetteSettings {
+    pub host: String,
+    pub port: Option<u16>,
+    pub binary: Option<PathBuf>,
+    pub connect_existing: bool,
+
+    /// Brings up the Browser Toolbox when starting Firefox,
+    /// letting you debug internals.
+    pub jsdebugger: bool,
+
+    pub android_storage: AndroidStorageInput,
+}
+
+#[derive(Default)]
+pub struct MarionetteHandler {
+    pub connection: Mutex<Option<MarionetteConnection>>,
+    pub settings: MarionetteSettings,
+    pub browser: Option<Browser>,
+}
+
+impl MarionetteHandler {
+    pub fn new(settings: MarionetteSettings) -> MarionetteHandler {
+        MarionetteHandler {
+            connection: Mutex::new(None),
+            settings,
+            browser: None,
+        }
+    }
+
+    pub fn create_connection(
+        &mut self,
+        session_id: &Option<String>,
+        new_session_parameters: &NewSessionParameters,
+    ) -> WebDriverResult<Map<String, Value>> {
+        let (options, capabilities) = {
+            let mut fx_capabilities = FirefoxCapabilities::new(self.settings.binary.as_ref());
+            let mut capabilities = new_session_parameters
+                .match_browser(&mut fx_capabilities)?
+                .ok_or_else(|| {
+                    WebDriverError::new(
+                        ErrorStatus::SessionNotCreated,
+                        "Unable to find a matching set of capabilities",
+                    )
+                })?;
+
+            let options = FirefoxOptions::from_capabilities(
+                fx_capabilities.chosen_binary,
+                self.settings.android_storage,
+                &mut capabilities,
+            )?;
+            (options, capabilities)
+        };
+
+        if let Some(l) = options.log.level {
+            logging::set_max_level(l);
+        }
+
+        let host = self.settings.host.to_owned();
+        let port = self.settings.port.unwrap_or(get_free_port(&host)?);
+
+        match options.android {
+            Some(_) => {
+                // TODO: support connecting to running Apps.  There's no real obstruction here,
+                // just some details about port forwarding to work through.  We can't follow
+                // `chromedriver` here since it uses an abstract socket rather than a TCP socket:
+                // see bug 1240830 for thoughts on doing that for Marionette.
+                if self.settings.connect_existing {
+                    return Err(WebDriverError::new(
+                        ErrorStatus::SessionNotCreated,
+                        "Cannot connect to an existing Android App yet",
+                    ));
+                }
+
+                self.start_android(port, options)?;
+            }
+            None => {
+                if !self.settings.connect_existing {
+                    self.start_browser(port, options)?;
+                }
+            }
+        }
+
+        let mut connection = MarionetteConnection::new(host, port, session_id.clone());
+        connection.connect(&mut self.browser).or_else(|e| {
+            match self.browser {
+                Some(Browser::Host(ref mut runner)) => {
+                    runner.kill()?;
+                }
+                Some(Browser::Target(ref mut handler)) => {
+                    handler.force_stop().map_err(|e| {
+                        WebDriverError::new(ErrorStatus::UnknownError, e.to_string())
+                    })?;
+                }
+                _ => {}
+            }
+
+            Err(e)
+        })?;
+        self.connection = Mutex::new(Some(connection));
+        Ok(capabilities)
+    }
+
+    fn start_android(&mut self, port: u16, options: FirefoxOptions) -> WebDriverResult<()> {
+        let android_options = options.android.unwrap();
+
+        let handler = AndroidHandler::new(&android_options, port)?;
+
+        // Profile management.
+        let is_custom_profile = options.profile.is_some();
+
+        let mut profile = options.profile.unwrap_or(Profile::new()?);
+
+        self.set_prefs(
+            handler.target_port,
+            &mut profile,
+            is_custom_profile,
+            options.prefs,
+        )
+        .map_err(|e| {
+            WebDriverError::new(
+                ErrorStatus::SessionNotCreated,
+                format!("Failed to set preferences: {}", e),
+            )
+        })?;
+
+        handler
+            .prepare(&profile, options.env.unwrap_or_default())
+            .map_err(|e| WebDriverError::new(ErrorStatus::UnknownError, e.to_string()))?;
+
+        handler
+            .launch()
+            .map_err(|e| WebDriverError::new(ErrorStatus::UnknownError, e.to_string()))?;
+
+        self.browser = Some(Browser::Target(handler));
+
+        Ok(())
+    }
+
+    fn start_browser(&mut self, port: u16, options: FirefoxOptions) -> WebDriverResult<()> {
+        let binary = options.binary.ok_or_else(|| {
+            WebDriverError::new(
+                ErrorStatus::SessionNotCreated,
+                "Expected browser binary location, but unable to find \
+             binary in default location, no \
+             'moz:firefoxOptions.binary' capability provided, and \
+             no binary flag set on the command line",
+            )
+        })?;
+
+        let is_custom_profile = options.profile.is_some();
+
+        let mut profile = match options.profile {
+            Some(x) => x,
+            None => Profile::new()?,
+        };
+
+        self.set_prefs(port, &mut profile, is_custom_profile, options.prefs)
+            .map_err(|e| {
+                WebDriverError::new(
+                    ErrorStatus::SessionNotCreated,
+                    format!("Failed to set preferences: {}", e),
+                )
+            })?;
+
+        let mut runner = FirefoxRunner::new(&binary, profile);
+
+        runner.arg("--marionette");
+        if self.settings.jsdebugger {
+            runner.arg("--jsdebugger");
+        }
+        if let Some(args) = options.args.as_ref() {
+            runner.args(args);
+        }
+
+        // https://developer.mozilla.org/docs/Environment_variables_affecting_crash_reporting
+        runner
+            .env("MOZ_CRASHREPORTER", "1")
+            .env("MOZ_CRASHREPORTER_NO_REPORT", "1")
+            .env("MOZ_CRASHREPORTER_SHUTDOWN", "1");
+
+        let browser_proc = runner.start().map_err(|e| {
+            WebDriverError::new(
+                ErrorStatus::SessionNotCreated,
+                format!("Failed to start browser {}: {}", binary.display(), e),
+            )
+        })?;
+        self.browser = Some(Browser::Host(browser_proc));
+
+        Ok(())
+    }
+
+    pub fn set_prefs(
+        &self,
+        port: u16,
+        profile: &mut Profile,
+        custom_profile: bool,
+        extra_prefs: Vec<(String, Pref)>,
+    ) -> WebDriverResult<()> {
+        let prefs = profile.user_prefs().map_err(|_| {
+            WebDriverError::new(
+                ErrorStatus::UnknownError,
+                "Unable to read profile preferences file",
+            )
+        })?;
+
+        for &(ref name, ref value) in prefs::DEFAULT.iter() {
+            if !custom_profile || !prefs.contains_key(name) {
+                prefs.insert((*name).to_string(), (*value).clone());
+            }
+        }
+
+        prefs.insert_slice(&extra_prefs[..]);
+
+        if self.settings.jsdebugger {
+            prefs.insert("devtools.browsertoolbox.panel", Pref::new("jsdebugger"));
+            prefs.insert("devtools.debugger.remote-enabled", Pref::new(true));
+            prefs.insert("devtools.chrome.enabled", Pref::new(true));
+            prefs.insert("devtools.debugger.prompt-connection", Pref::new(false));
+            prefs.insert("marionette.debugging.clicktostart", Pref::new(true));
+        }
+
+        prefs.insert("marionette.log.level", logging::max_level().into());
+        prefs.insert("marionette.port", Pref::new(port));
+
+        prefs.write().map_err(|e| {
+            WebDriverError::new(
+                ErrorStatus::UnknownError,
+                format!("Unable to write Firefox profile: {}", e),
+            )
+        })
+    }
+}
+
+impl WebDriverHandler<GeckoExtensionRoute> for MarionetteHandler {
+    fn handle_command(
+        &mut self,
+        _: &Option<Session>,
+        msg: WebDriverMessage<GeckoExtensionRoute>,
+    ) -> WebDriverResult<WebDriverResponse> {
+        let mut resolved_capabilities = None;
+        {
+            let mut capabilities_options = None;
+            // First handle the status message which doesn't actually require a marionette
+            // connection or message
+            if let Status = msg.command {
+                let (ready, message) = self
+                    .connection
+                    .lock()
+                    .map(|ref connection| {
+                        connection
+                            .as_ref()
+                            .map(|_| (false, "Session already started"))
+                            .unwrap_or((true, ""))
+                    })
+                    .unwrap_or((false, "geckodriver internal error"));
+                let mut value = Map::new();
+                value.insert("ready".to_string(), Value::Bool(ready));
+                value.insert("message".to_string(), Value::String(message.into()));
+                return Ok(WebDriverResponse::Generic(ValueResponse(Value::Object(
+                    value,
+                ))));
+            }
+
+            match self.connection.lock() {
+                Ok(ref connection) => {
+                    if connection.is_none() {
+                        match msg.command {
+                            NewSession(ref capabilities) => {
+                                capabilities_options = Some(capabilities);
+                            }
+                            _ => {
+                                return Err(WebDriverError::new(
+                                    ErrorStatus::InvalidSessionId,
+                                    "Tried to run command without establishing a connection",
+                                ));
+                            }
+                        }
+                    }
+                }
+                Err(_) => {
+                    return Err(WebDriverError::new(
+                        ErrorStatus::UnknownError,
+                        "Failed to aquire Marionette connection",
+                    ))
+                }
+            }
+            if let Some(capabilities) = capabilities_options {
+                resolved_capabilities =
+                    Some(self.create_connection(&msg.session_id, &capabilities)?);
+            }
+        }
+
+        match self.connection.lock() {
+            Ok(ref mut connection) => {
+                match connection.as_mut() {
+                    Some(conn) => {
+                        conn.send_command(resolved_capabilities, &msg)
+                            .map_err(|mut err| {
+                                // Shutdown the browser if no session can
+                                // be established due to errors.
+                                if let NewSession(_) = msg.command {
+                                    err.delete_session = true;
+                                }
+                                err
+                            })
+                    }
+                    None => panic!("Connection missing"),
+                }
+            }
+            Err(_) => Err(WebDriverError::new(
+                ErrorStatus::UnknownError,
+                "Failed to aquire Marionette connection",
+            )),
+        }
+    }
+
+    fn delete_session(&mut self, session: &Option<Session>) {
+        if let Some(ref s) = *session {
+            let delete_session = WebDriverMessage {
+                session_id: Some(s.id.clone()),
+                command: WebDriverCommand::DeleteSession,
+            };
+            let _ = self.handle_command(session, delete_session);
+        }
+
+        if let Ok(ref mut connection) = self.connection.lock() {
+            if let Some(conn) = connection.as_mut() {
+                conn.close();
+            }
+        }
+
+        match self.browser {
+            Some(Browser::Host(ref mut runner)) => {
+                // TODO(https://bugzil.la/1443922):
+                // Use toolkit.asyncshutdown.crash_timout pref
+                match runner.wait(time::Duration::from_secs(70)) {
+                    Ok(x) => debug!("Browser process stopped: {}", x),
+                    Err(e) => error!("Failed to stop browser process: {}", e),
+                }
+            }
+            Some(Browser::Target(ref mut handler)) => {
+                // Try to force-stop the process on the target device
+                match handler.force_stop() {
+                    Ok(_) => debug!("Android package force-stopped"),
+                    Err(e) => error!("Failed to force-stop Android package: {}", e),
+                }
+            }
+            None => {}
+        }
+
+        self.connection = Mutex::new(None);
+        self.browser = None;
+    }
+}
+
+pub struct MarionetteSession {
+    pub session_id: String,
+    protocol: Option<u16>,
+    application_type: Option<String>,
+    command_id: MessageId,
+}
+
+impl MarionetteSession {
+    pub fn new(session_id: Option<String>) -> MarionetteSession {
+        let initital_id = session_id.unwrap_or_else(|| "".to_string());
+        MarionetteSession {
+            session_id: initital_id,
+            protocol: None,
+            application_type: None,
+            command_id: 0,
+        }
+    }
+
+    pub fn update(
+        &mut self,
+        msg: &WebDriverMessage<GeckoExtensionRoute>,
+        resp: &MarionetteResponse,
+    ) -> WebDriverResult<()> {
+        if let NewSession(_) = msg.command {
+            let session_id = try_opt!(
+                try_opt!(
+                    resp.result.get("sessionId"),
+                    ErrorStatus::SessionNotCreated,
+                    "Unable to get session id"
+                )
+                .as_str(),
+                ErrorStatus::SessionNotCreated,
+                "Unable to convert session id to string"
+            );
+            self.session_id = session_id.to_string().clone();
+        };
+        Ok(())
+    }
+
+    /// Converts a Marionette JSON response into a `WebElement`.
+    ///
+    /// Note that it currently coerces all chrome elements, web frames, and web
+    /// windows also into web elements.  This will change at a later point.
+    fn to_web_element(&self, json_data: &Value) -> WebDriverResult<WebElement> {
+        let data = try_opt!(
+            json_data.as_object(),
+            ErrorStatus::UnknownError,
+            "Failed to convert data to an object"
+        );
+
+        let chrome_element = data.get(CHROME_ELEMENT_KEY);
+        let element = data.get(ELEMENT_KEY);
+        let frame = data.get(FRAME_KEY);
+        let window = data.get(WINDOW_KEY);
+
+        let value = try_opt!(
+            element.or(chrome_element).or(frame).or(window),
+            ErrorStatus::UnknownError,
+            "Failed to extract web element from Marionette response"
+        );
+        let id = try_opt!(
+            value.as_str(),
+            ErrorStatus::UnknownError,
+            "Failed to convert web element reference value to string"
+        )
+        .to_string();
+        Ok(WebElement(id))
+    }
+
+    pub fn next_command_id(&mut self) -> MessageId {
+        self.command_id += 1;
+        self.command_id
+    }
+
+    pub fn response(
+        &mut self,
+        msg: &WebDriverMessage<GeckoExtensionRoute>,
+        resp: MarionetteResponse,
+    ) -> WebDriverResult<WebDriverResponse> {
+        use self::GeckoExtensionCommand::*;
+
+        if resp.id != self.command_id {
+            return Err(WebDriverError::new(
+                ErrorStatus::UnknownError,
+                format!(
+                    "Marionette responses arrived out of sequence, expected {}, got {}",
+                    self.command_id, resp.id
+                ),
+            ));
+        }
+
+        if let Some(error) = resp.error {
+            return Err(error.into());
+        }
+
+        self.update(msg, &resp)?;
+
+        Ok(match msg.command {
+            // Everything that doesn't have a response value
+            Get(_)
+            | GoBack
+            | GoForward
+            | Refresh
+            | SetTimeouts(_)
+            | SwitchToWindow(_)
+            | SwitchToFrame(_)
+            | SwitchToParentFrame
+            | AddCookie(_)
+            | DeleteCookies
+            | DeleteCookie(_)
+            | DismissAlert
+            | AcceptAlert
+            | SendAlertText(_)
+            | ElementClick(_)
+            | ElementClear(_)
+            | ElementSendKeys(_, _)
+            | PerformActions(_)
+            | ReleaseActions => WebDriverResponse::Void,
+            // Things that simply return the contents of the marionette "value" property
+            GetCurrentUrl
+            | GetTitle
+            | GetPageSource
+            | GetWindowHandle
+            | IsDisplayed(_)
+            | IsSelected(_)
+            | GetElementAttribute(_, _)
+            | GetElementProperty(_, _)
+            | GetCSSValue(_, _)
+            | GetElementText(_)
+            | GetElementTagName(_)
+            | IsEnabled(_)
+            | ExecuteScript(_)
+            | ExecuteAsyncScript(_)
+            | GetAlertText
+            | TakeScreenshot
+            | Print(_)
+            | TakeElementScreenshot(_) => {
+                WebDriverResponse::Generic(resp.into_value_response(true)?)
+            }
+            GetTimeouts => {
+                let script = match try_opt!(
+                    resp.result.get("script"),
+                    ErrorStatus::UnknownError,
+                    "Missing field: script"
+                ) {
+                    Value::Null => None,
+                    n => try_opt!(
+                        Some(n.as_u64()),
+                        ErrorStatus::UnknownError,
+                        "Failed to interpret script timeout duration as u64"
+                    ),
+                };
+                // Check for the spec-compliant "pageLoad", but also for "page load",
+                // which was sent by Firefox 52 and earlier.
+                let page_load = try_opt!(
+                    try_opt!(
+                        resp.result
+                            .get("pageLoad")
+                            .or_else(|| resp.result.get("page load")),
+                        ErrorStatus::UnknownError,
+                        "Missing field: pageLoad"
+                    )
+                    .as_u64(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret page load duration as u64"
+                );
+                let implicit = try_opt!(
+                    try_opt!(
+                        resp.result.get("implicit"),
+                        ErrorStatus::UnknownError,
+                        "Missing field: implicit"
+                    )
+                    .as_u64(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret implicit search duration as u64"
+                );
+
+                WebDriverResponse::Timeouts(TimeoutsResponse {
+                    script,
+                    page_load,
+                    implicit,
+                })
+            }
+            Status => panic!("Got status command that should already have been handled"),
+            GetWindowHandles => WebDriverResponse::Generic(resp.into_value_response(false)?),
+            NewWindow(_) => {
+                let handle: String = try_opt!(
+                    try_opt!(
+                        resp.result.get("handle"),
+                        ErrorStatus::UnknownError,
+                        "Failed to find handle field"
+                    )
+                    .as_str(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret handle as string"
+                )
+                .into();
+                let typ: String = try_opt!(
+                    try_opt!(
+                        resp.result.get("type"),
+                        ErrorStatus::UnknownError,
+                        "Failed to find type field"
+                    )
+                    .as_str(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret type as string"
+                )
+                .into();
+
+                WebDriverResponse::NewWindow(NewWindowResponse { handle, typ })
+            }
+            CloseWindow => {
+                let data = try_opt!(
+                    resp.result.as_array(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret value as array"
+                );
+                let handles = data
+                    .iter()
+                    .map(|x| {
+                        Ok(try_opt!(
+                            x.as_str(),
+                            ErrorStatus::UnknownError,
+                            "Failed to interpret window handle as string"
+                        )
+                        .to_owned())
+                    })
+                    .collect::<Result<Vec<_>, _>>()?;
+                WebDriverResponse::CloseWindow(CloseWindowResponse(handles))
+            }
+            GetElementRect(_) => {
+                let x = try_opt!(
+                    try_opt!(
+                        resp.result.get("x"),
+                        ErrorStatus::UnknownError,
+                        "Failed to find x field"
+                    )
+                    .as_f64(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret x as float"
+                );
+
+                let y = try_opt!(
+                    try_opt!(
+                        resp.result.get("y"),
+                        ErrorStatus::UnknownError,
+                        "Failed to find y field"
+                    )
+                    .as_f64(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret y as float"
+                );
+
+                let width = try_opt!(
+                    try_opt!(
+                        resp.result.get("width"),
+                        ErrorStatus::UnknownError,
+                        "Failed to find width field"
+                    )
+                    .as_f64(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret width as float"
+                );
+
+                let height = try_opt!(
+                    try_opt!(
+                        resp.result.get("height"),
+                        ErrorStatus::UnknownError,
+                        "Failed to find height field"
+                    )
+                    .as_f64(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret width as float"
+                );
+
+                let rect = ElementRectResponse {
+                    x,
+                    y,
+                    width,
+                    height,
+                };
+                WebDriverResponse::ElementRect(rect)
+            }
+            FullscreenWindow | MinimizeWindow | MaximizeWindow | GetWindowRect
+            | SetWindowRect(_) => {
+                let width = try_opt!(
+                    try_opt!(
+                        resp.result.get("width"),
+                        ErrorStatus::UnknownError,
+                        "Failed to find width field"
+                    )
+                    .as_u64(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret width as positive integer"
+                );
+
+                let height = try_opt!(
+                    try_opt!(
+                        resp.result.get("height"),
+                        ErrorStatus::UnknownError,
+                        "Failed to find heigenht field"
+                    )
+                    .as_u64(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret height as positive integer"
+                );
+
+                let x = try_opt!(
+                    try_opt!(
+                        resp.result.get("x"),
+                        ErrorStatus::UnknownError,
+                        "Failed to find x field"
+                    )
+                    .as_i64(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret x as integer"
+                );
+
+                let y = try_opt!(
+                    try_opt!(
+                        resp.result.get("y"),
+                        ErrorStatus::UnknownError,
+                        "Failed to find y field"
+                    )
+                    .as_i64(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret y as integer"
+                );
+
+                let rect = WindowRectResponse {
+                    x: x as i32,
+                    y: y as i32,
+                    width: width as i32,
+                    height: height as i32,
+                };
+                WebDriverResponse::WindowRect(rect)
+            }
+            GetCookies => {
+                let cookies: Vec<Cookie> = serde_json::from_value(resp.result)?;
+                WebDriverResponse::Cookies(CookiesResponse(cookies))
+            }
+            GetNamedCookie(ref name) => {
+                let mut cookies: Vec<Cookie> = serde_json::from_value(resp.result)?;
+                cookies.retain(|x| x.name == *name);
+                let cookie = try_opt!(
+                    cookies.pop(),
+                    ErrorStatus::NoSuchCookie,
+                    format!("No cookie with name {}", name)
+                );
+                WebDriverResponse::Cookie(CookieResponse(cookie))
+            }
+            FindElement(_) | FindElementElement(_, _) => {
+                let element = self.to_web_element(try_opt!(
+                    resp.result.get("value"),
+                    ErrorStatus::UnknownError,
+                    "Failed to find value field"
+                ))?;
+                WebDriverResponse::Generic(ValueResponse(serde_json::to_value(element)?))
+            }
+            FindElements(_) | FindElementElements(_, _) => {
+                let element_vec = try_opt!(
+                    resp.result.as_array(),
+                    ErrorStatus::UnknownError,
+                    "Failed to interpret value as array"
+                );
+                let elements = element_vec
+                    .iter()
+                    .map(|x| self.to_web_element(x))
+                    .collect::<Result<Vec<_>, _>>()?;
+
+                // TODO(Henrik): How to remove unwrap?
+                WebDriverResponse::Generic(ValueResponse(Value::Array(
+                    elements
+                        .iter()
+                        .map(|x| serde_json::to_value(x).unwrap())
+                        .collect(),
+                )))
+            }
+            GetActiveElement => {
+                let element = self.to_web_element(try_opt!(
+                    resp.result.get("value"),
+                    ErrorStatus::UnknownError,
+                    "Failed to find value field"
+                ))?;
+                WebDriverResponse::Generic(ValueResponse(serde_json::to_value(element)?))
+            }
+            NewSession(_) => {
+                let session_id = try_opt!(
+                    try_opt!(
+                        resp.result.get("sessionId"),
+                        ErrorStatus::InvalidSessionId,
+                        "Failed to find sessionId field"
+                    )
+                    .as_str(),
+                    ErrorStatus::InvalidSessionId,
+                    "sessionId is not a string"
+                );
+
+                let mut capabilities = try_opt!(
+                    try_opt!(
+                        resp.result.get("capabilities"),
+                        ErrorStatus::UnknownError,
+                        "Failed to find capabilities field"
+                    )
+                    .as_object(),
+                    ErrorStatus::UnknownError,
+                    "capabilities field is not an object"
+                )
+                .clone();
+
+                capabilities.insert("moz:geckodriverVersion".into(), build::build_info().into());
+
+                WebDriverResponse::NewSession(NewSessionResponse::new(
+                    session_id.to_string(),
+                    Value::Object(capabilities.clone()),
+                ))
+            }
+            DeleteSession => WebDriverResponse::DeleteSession,
+            Extension(ref extension) => match extension {
+                GetContext => WebDriverResponse::Generic(resp.into_value_response(true)?),
+                SetContext(_) => WebDriverResponse::Void,
+                InstallAddon(_) => WebDriverResponse::Generic(resp.into_value_response(true)?),
+                UninstallAddon(_) => WebDriverResponse::Void,
+                TakeFullScreenshot => WebDriverResponse::Generic(resp.into_value_response(true)?),
+            },
+        })
+    }
+}
+
+fn try_convert_to_marionette_message(
+    msg: &WebDriverMessage<GeckoExtensionRoute>,
+) -> WebDriverResult<Option<Command>> {
+    use self::GeckoExtensionCommand::*;
+    use self::WebDriverCommand::*;
+
+    Ok(match msg.command {
+        AcceptAlert => Some(Command::WebDriver(MarionetteWebDriverCommand::AcceptAlert)),
+        AddCookie(ref x) => Some(Command::WebDriver(MarionetteWebDriverCommand::AddCookie(
+            x.to_marionette()?,
+        ))),
+        CloseWindow => Some(Command::WebDriver(MarionetteWebDriverCommand::CloseWindow)),
+        DeleteCookie(ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::DeleteCookie(x.clone()),
+        )),
+        DeleteCookies => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::DeleteCookies,
+        )),
+        DeleteSession => Some(Command::Marionette(
+            marionette_rs::marionette::Command::DeleteSession {
+                flags: vec![AppStatus::eForceQuit],
+            },
+        )),
+        DismissAlert => Some(Command::WebDriver(MarionetteWebDriverCommand::DismissAlert)),
+        ElementClear(ref e) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::ElementClear(e.to_marionette()?),
+        )),
+        ElementClick(ref e) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::ElementClick(e.to_marionette()?),
+        )),
+        ElementSendKeys(ref e, ref x) => {
+            let keys = x.to_marionette()?;
+            Some(Command::WebDriver(
+                MarionetteWebDriverCommand::ElementSendKeys {
+                    id: e.clone().to_string(),
+                    text: keys.text.clone(),
+                    value: keys.value.clone(),
+                },
+            ))
+        }
+        ExecuteAsyncScript(ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::ExecuteAsyncScript(x.to_marionette()?),
+        )),
+        ExecuteScript(ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::ExecuteScript(x.to_marionette()?),
+        )),
+        FindElement(ref x) => Some(Command::WebDriver(MarionetteWebDriverCommand::FindElement(
+            x.to_marionette()?,
+        ))),
+        FindElements(ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::FindElements(x.to_marionette()?),
+        )),
+        FindElementElement(ref e, ref x) => {
+            let locator = x.to_marionette()?;
+            Some(Command::WebDriver(
+                MarionetteWebDriverCommand::FindElementElement {
+                    element: e.clone().to_string(),
+                    using: locator.using.clone(),
+                    value: locator.value.clone(),
+                },
+            ))
+        }
+        FindElementElements(ref e, ref x) => {
+            let locator = x.to_marionette()?;
+            Some(Command::WebDriver(
+                MarionetteWebDriverCommand::FindElementElements {
+                    element: e.clone().to_string(),
+                    using: locator.using.clone(),
+                    value: locator.value.clone(),
+                },
+            ))
+        }
+        FullscreenWindow => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::FullscreenWindow,
+        )),
+        Get(ref x) => Some(Command::WebDriver(MarionetteWebDriverCommand::Get(
+            x.to_marionette()?,
+        ))),
+        GetActiveElement => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::GetActiveElement,
+        )),
+        GetAlertText => Some(Command::WebDriver(MarionetteWebDriverCommand::GetAlertText)),
+        GetCookies | GetNamedCookie(_) => {
+            Some(Command::WebDriver(MarionetteWebDriverCommand::GetCookies))
+        }
+        GetCSSValue(ref e, ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::GetCSSValue {
+                id: e.clone().to_string(),
+                property: x.clone(),
+            },
+        )),
+        GetCurrentUrl => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::GetCurrentUrl,
+        )),
+        GetElementAttribute(ref e, ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::GetElementAttribute {
+                id: e.clone().to_string(),
+                name: x.clone(),
+            },
+        )),
+        GetElementProperty(ref e, ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::GetElementProperty {
+                id: e.clone().to_string(),
+                name: x.clone(),
+            },
+        )),
+        GetElementRect(ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::GetElementRect(x.to_marionette()?),
+        )),
+        GetElementTagName(ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::GetElementTagName(x.to_marionette()?),
+        )),
+        GetElementText(ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::GetElementText(x.to_marionette()?),
+        )),
+        GetPageSource => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::GetPageSource,
+        )),
+        GetTitle => Some(Command::WebDriver(MarionetteWebDriverCommand::GetTitle)),
+        GetWindowHandle => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::GetWindowHandle,
+        )),
+        GetWindowHandles => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::GetWindowHandles,
+        )),
+        GetWindowRect => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::GetWindowRect,
+        )),
+        GetTimeouts => Some(Command::WebDriver(MarionetteWebDriverCommand::GetTimeouts)),
+        GoBack => Some(Command::WebDriver(MarionetteWebDriverCommand::GoBack)),
+        GoForward => Some(Command::WebDriver(MarionetteWebDriverCommand::GoForward)),
+        IsDisplayed(ref x) => Some(Command::WebDriver(MarionetteWebDriverCommand::IsDisplayed(
+            x.to_marionette()?,
+        ))),
+        IsEnabled(ref x) => Some(Command::WebDriver(MarionetteWebDriverCommand::IsEnabled(
+            x.to_marionette()?,
+        ))),
+        IsSelected(ref x) => Some(Command::WebDriver(MarionetteWebDriverCommand::IsSelected(
+            x.to_marionette()?,
+        ))),
+        MaximizeWindow => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::MaximizeWindow,
+        )),
+        MinimizeWindow => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::MinimizeWindow,
+        )),
+        NewWindow(ref x) => Some(Command::WebDriver(MarionetteWebDriverCommand::NewWindow(
+            x.to_marionette()?,
+        ))),
+        Print(ref x) => Some(Command::WebDriver(MarionetteWebDriverCommand::Print(
+            x.to_marionette()?,
+        ))),
+        Refresh => Some(Command::WebDriver(MarionetteWebDriverCommand::Refresh)),
+        ReleaseActions => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::ReleaseActions,
+        )),
+        SendAlertText(ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::SendAlertText(x.to_marionette()?),
+        )),
+        SetTimeouts(ref x) => Some(Command::WebDriver(MarionetteWebDriverCommand::SetTimeouts(
+            x.to_marionette()?,
+        ))),
+        SetWindowRect(ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::SetWindowRect(x.to_marionette()?),
+        )),
+        SwitchToFrame(ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::SwitchToFrame(x.to_marionette()?),
+        )),
+        SwitchToParentFrame => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::SwitchToParentFrame,
+        )),
+        SwitchToWindow(ref x) => Some(Command::WebDriver(
+            MarionetteWebDriverCommand::SwitchToWindow(x.to_marionette()?),
+        )),
+        TakeElementScreenshot(ref e) => {
+            let screenshot = ScreenshotOptions {
+                id: Some(e.clone().to_string()),
+                highlights: vec![],
+                full: false,
+            };
+            Some(Command::WebDriver(
+                MarionetteWebDriverCommand::TakeElementScreenshot(screenshot),
+            ))
+        }
+        TakeScreenshot => {
+            let screenshot = ScreenshotOptions {
+                id: None,
+                highlights: vec![],
+                full: false,
+            };
+            Some(Command::WebDriver(
+                MarionetteWebDriverCommand::TakeScreenshot(screenshot),
+            ))
+        }
+        Extension(ref extension) => match extension {
+            TakeFullScreenshot => {
+                let screenshot = ScreenshotOptions {
+                    id: None,
+                    highlights: vec![],
+                    full: true,
+                };
+                Some(Command::WebDriver(
+                    MarionetteWebDriverCommand::TakeFullScreenshot(screenshot),
+                ))
+            }
+            _ => None,
+        },
+        _ => None,
+    })
+}
+
+#[derive(Debug, PartialEq)]
+pub struct MarionetteCommand {
+    pub id: MessageId,
+    pub name: String,
+    pub params: Map<String, Value>,
+}
+
+impl Serialize for MarionetteCommand {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let data = (&0, &self.id, &self.name, &self.params);
+        data.serialize(serializer)
+    }
+}
+
+impl MarionetteCommand {
+    fn new(id: MessageId, name: String, params: Map<String, Value>) -> MarionetteCommand {
+        MarionetteCommand { id, name, params }
+    }
+
+    fn encode_msg<T>(msg: T) -> WebDriverResult<String>
+    where
+        T: serde::Serialize,
+    {
+        let data = serde_json::to_string(&msg)?;
+
+        Ok(format!("{}:{}", data.len(), data))
+    }
+
+    fn from_webdriver_message(
+        id: MessageId,
+        capabilities: Option<Map<String, Value>>,
+        msg: &WebDriverMessage<GeckoExtensionRoute>,
+    ) -> WebDriverResult<String> {
+        use self::GeckoExtensionCommand::*;
+
+        if let Some(cmd) = try_convert_to_marionette_message(msg)? {
+            let req = Message::Incoming(Request(id, cmd));
+            MarionetteCommand::encode_msg(req)
+        } else {
+            let (opt_name, opt_parameters) = match msg.command {
+                Status => panic!("Got status command that should already have been handled"),
+                NewSession(_) => {
+                    let caps = capabilities
+                        .expect("Tried to create new session without processing capabilities");
+
+                    let mut data = Map::new();
+                    for (k, v) in caps.iter() {
+                        data.insert(k.to_string(), serde_json::to_value(v)?);
+                    }
+
+                    (Some("WebDriver:NewSession"), Some(Ok(data)))
+                }
+                PerformActions(ref x) => {
+                    (Some("WebDriver:PerformActions"), Some(x.to_marionette()))
+                }
+                Extension(ref extension) => match extension {
+                    GetContext => (Some("Marionette:GetContext"), None),
+                    InstallAddon(x) => (Some("Addon:Install"), Some(x.to_marionette())),
+                    SetContext(x) => (Some("Marionette:SetContext"), Some(x.to_marionette())),
+                    UninstallAddon(x) => (Some("Addon:Uninstall"), Some(x.to_marionette())),
+                    _ => (None, None),
+                },
+                _ => (None, None),
+            };
+
+            let name = try_opt!(
+                opt_name,
+                ErrorStatus::UnsupportedOperation,
+                "Operation not supported"
+            );
+            let parameters = opt_parameters.unwrap_or_else(|| Ok(Map::new()))?;
+
+            let req = MarionetteCommand::new(id, name.into(), parameters);
+            MarionetteCommand::encode_msg(req)
+        }
+    }
+}
+
+#[derive(Debug, PartialEq)]
+pub struct MarionetteResponse {
+    pub id: MessageId,
+    pub error: Option<MarionetteError>,
+    pub result: Value,
+}
+
+impl<'de> Deserialize<'de> for MarionetteResponse {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        #[derive(Deserialize)]
+        struct ResponseWrapper {
+            msg_type: u64,
+            id: MessageId,
+            error: Option<MarionetteError>,
+            result: Value,
+        }
+
+        let wrapper: ResponseWrapper = Deserialize::deserialize(deserializer)?;
+
+        if wrapper.msg_type != 1 {
+            return Err(de::Error::custom(
+                "Expected '1' in first element of response",
+            ));
+        };
+
+        Ok(MarionetteResponse {
+            id: wrapper.id,
+            error: wrapper.error,
+            result: wrapper.result,
+        })
+    }
+}
+
+impl MarionetteResponse {
+    fn into_value_response(self, value_required: bool) -> WebDriverResult<ValueResponse> {
+        let value: &Value = if value_required {
+            try_opt!(
+                self.result.get("value"),
+                ErrorStatus::UnknownError,
+                "Failed to find value field"
+            )
+        } else {
+            &self.result
+        };
+
+        Ok(ValueResponse(value.clone()))
+    }
+}
+
+#[derive(Debug, PartialEq, Serialize, Deserialize)]
+pub struct MarionetteError {
+    #[serde(rename = "error")]
+    pub code: String,
+    pub message: String,
+    pub stacktrace: Option<String>,
+}
+
+impl Into<WebDriverError> for MarionetteError {
+    fn into(self) -> WebDriverError {
+        let status = ErrorStatus::from(self.code);
+        let message = self.message;
+
+        if let Some(stack) = self.stacktrace {
+            WebDriverError::new_with_stack(status, message, stack)
+        } else {
+            WebDriverError::new(status, message)
+        }
+    }
+}
+
+fn get_free_port(host: &str) -> IoResult<u16> {
+    TcpListener::bind((host, 0))
+        .and_then(|stream| stream.local_addr())
+        .map(|x| x.port())
+}
+
+pub struct MarionetteConnection {
+    host: String,
+    port: u16,
+    stream: Option<TcpStream>,
+    pub session: MarionetteSession,
+}
+
+impl MarionetteConnection {
+    pub fn new(host: String, port: u16, session_id: Option<String>) -> MarionetteConnection {
+        let session = MarionetteSession::new(session_id);
+        MarionetteConnection {
+            host,
+            port,
+            stream: None,
+            session,
+        }
+    }
+
+    pub fn connect(&mut self, browser: &mut Option<Browser>) -> WebDriverResult<()> {
+        let timeout = time::Duration::from_secs(60);
+        let poll_interval = time::Duration::from_millis(100);
+        let now = time::Instant::now();
+
+        debug!(
+            "Waiting {}s to connect to browser on {}:{}",
+            timeout.as_secs(),
+            self.host,
+            self.port
+        );
+
+        loop {
+            // immediately abort connection attempts if process disappears
+            if let Some(Browser::Host(ref mut runner)) = *browser {
+                let exit_status = match runner.try_wait() {
+                    Ok(Some(status)) => Some(
+                        status
+                            .code()
+                            .map(|c| c.to_string())
+                            .unwrap_or_else(|| "signal".into()),
+                    ),
+                    Ok(None) => None,
+                    Err(_) => Some("{unknown}".into()),
+                };
+                if let Some(s) = exit_status {
+                    return Err(WebDriverError::new(
+                        ErrorStatus::UnknownError,
+                        format!("Process unexpectedly closed with status {}", s),
+                    ));
+                }
+            }
+
+            let try_connect = || -> WebDriverResult<(TcpStream, MarionetteHandshake)> {
+                let mut stream = TcpStream::connect((&self.host[..], self.port))?;
+                let data = MarionetteConnection::handshake(&mut stream)?;
+
+                Ok((stream, data))
+            };
+
+            match try_connect() {
+                Ok((stream, data)) => {
+                    debug!(
+                        "Connection to Marionette established on {}:{}.",
+                        self.host, self.port,
+                    );
+
+                    self.stream = Some(stream);
+                    self.session.application_type = Some(data.application_type);
+                    self.session.protocol = Some(data.protocol);
+                    break;
+                }
+                Err(e) => {
+                    if now.elapsed() < timeout {
+                        thread::sleep(poll_interval);
+                    } else {
+                        return Err(WebDriverError::new(ErrorStatus::Timeout, e.to_string()));
+                    }
+                }
+            }
+        }
+
+        Ok(())
+    }
+
+    fn handshake(stream: &mut TcpStream) -> WebDriverResult<MarionetteHandshake> {
+        let resp = (match stream.read_timeout() {
+            Ok(timeout) => {
+                // If platform supports changing the read timeout of the stream,
+                // use a short one only for the handshake with Marionette.
+                stream
+                    .set_read_timeout(Some(time::Duration::from_millis(100)))
+                    .ok();
+                let data = MarionetteConnection::read_resp(stream);
+                stream.set_read_timeout(timeout).ok();
+
+                data
+            }
+            _ => MarionetteConnection::read_resp(stream),
+        })
+        .map_err(|e| {
+            WebDriverError::new(
+                ErrorStatus::UnknownError,
+                format!("Socket timeout reading Marionette handshake data: {}", e),
+            )
+        })?;
+
+        let data = serde_json::from_str::<MarionetteHandshake>(&resp)?;
+
+        if data.application_type != "gecko" {
+            return Err(WebDriverError::new(
+                ErrorStatus::UnknownError,
+                format!("Unrecognized application type {}", data.application_type),
+            ));
+        }
+
+        if data.protocol != 3 {
+            return Err(WebDriverError::new(
+                ErrorStatus::UnknownError,
+                format!(
+                    "Unsupported Marionette protocol version {}, required 3",
+                    data.protocol
+                ),
+            ));
+        }
+
+        Ok(data)
+    }
+
+    pub fn close(&self) {}
+
+    pub fn send_command(
+        &mut self,
+        capabilities: Option<Map<String, Value>>,
+        msg: &WebDriverMessage<GeckoExtensionRoute>,
+    ) -> WebDriverResult<WebDriverResponse> {
+        let id = self.session.next_command_id();
+        let enc_cmd = MarionetteCommand::from_webdriver_message(id, capabilities, msg)?;
+        let resp_data = self.send(enc_cmd)?;
+        let data: MarionetteResponse = serde_json::from_str(&resp_data)?;
+
+        self.session.response(msg, data)
+    }
+
+    fn send(&mut self, data: String) -> WebDriverResult<String> {
+        let stream = match self.stream {
+            Some(ref mut stream) => {
+                if stream.write(&*data.as_bytes()).is_err() {
+                    let mut err = WebDriverError::new(
+                        ErrorStatus::UnknownError,
+                        "Failed to write request to stream",
+                    );
+                    err.delete_session = true;
+                    return Err(err);
+                }
+
+                stream
+            }
+            None => {
+                let mut err = WebDriverError::new(
+                    ErrorStatus::UnknownError,
+                    "Tried to write before opening stream",
+                );
+                err.delete_session = true;
+                return Err(err);
+            }
+        };
+
+        match MarionetteConnection::read_resp(stream) {
+            Ok(resp) => Ok(resp),
+            Err(_) => {
+                let mut err = WebDriverError::new(
+                    ErrorStatus::UnknownError,
+                    "Failed to decode response from marionette",
+                );
+                err.delete_session = true;
+                Err(err)
+            }
+        }
+    }
+
+    fn read_resp(stream: &mut TcpStream) -> IoResult<String> {
+        let mut bytes = 0usize;
+
+        loop {
+            let buf = &mut [0 as u8];
+            let num_read = stream.read(buf)?;
+            let byte = match num_read {
+                0 => {
+                    return Err(IoError::new(
+                        ErrorKind::Other,
+                        "EOF reading marionette message",
+                    ))
+                }
+                1 => buf[0] as char,
+                _ => panic!("Expected one byte got more"),
+            };
+            match byte {
+                '0'..='9' => {
+                    bytes *= 10;
+                    bytes += byte as usize - '0' as usize;
+                }
+                ':' => break,
+                _ => {}
+            }
+        }
+
+        let buf = &mut [0 as u8; 8192];
+        let mut payload = Vec::with_capacity(bytes);
+        let mut total_read = 0;
+        while total_read < bytes {
+            let num_read = stream.read(buf)?;
+            if num_read == 0 {
+                return Err(IoError::new(
+                    ErrorKind::Other,
+                    "EOF reading marionette message",
+                ));
+            }
+            total_read += num_read;
+            for x in &buf[..num_read] {
+                payload.push(*x);
+            }
+        }
+
+        // TODO(jgraham): Need to handle the error here
+        Ok(String::from_utf8(payload).unwrap())
+    }
+}
+
+trait ToMarionette<T> {
+    fn to_marionette(&self) -> WebDriverResult<T>;
+}
+
+impl ToMarionette<Map<String, Value>> for AddonInstallParameters {
+    fn to_marionette(&self) -> WebDriverResult<Map<String, Value>> {
+        let mut data = Map::new();
+        data.insert("path".to_string(), serde_json::to_value(&self.path)?);
+        if self.temporary.is_some() {
+            data.insert(
+                "temporary".to_string(),
+                serde_json::to_value(&self.temporary)?,
+            );
+        }
+        Ok(data)
+    }
+}
+
+impl ToMarionette<Map<String, Value>> for AddonUninstallParameters {
+    fn to_marionette(&self) -> WebDriverResult<Map<String, Value>> {
+        let mut data = Map::new();
+        data.insert("id".to_string(), Value::String(self.id.clone()));
+        Ok(data)
+    }
+}
+
+impl ToMarionette<Map<String, Value>> for GeckoContextParameters {
+    fn to_marionette(&self) -> WebDriverResult<Map<String, Value>> {
+        let mut data = Map::new();
+        data.insert(
+            "value".to_owned(),
+            serde_json::to_value(self.context.clone())?,
+        );
+        Ok(data)
+    }
+}
+
+impl ToMarionette<MarionettePrintParameters> for PrintParameters {
+    fn to_marionette(&self) -> WebDriverResult<MarionettePrintParameters> {
+        Ok(MarionettePrintParameters {
+            orientation: self.orientation.to_marionette()?,
+            scale: self.scale,
+            background: self.background,
+            page: self.page.to_marionette()?,
+            margin: self.margin.to_marionette()?,
+            page_ranges: self.page_ranges.clone(),
+            shrink_to_fit: self.shrink_to_fit,
+        })
+    }
+}
+
+impl ToMarionette<MarionettePrintOrientation> for PrintOrientation {
+    fn to_marionette(&self) -> WebDriverResult<MarionettePrintOrientation> {
+        Ok(match self {
+            PrintOrientation::Landscape => MarionettePrintOrientation::Landscape,
+            PrintOrientation::Portrait => MarionettePrintOrientation::Portrait,
+        })
+    }
+}
+
+impl ToMarionette<MarionettePrintPage> for PrintPage {
+    fn to_marionette(&self) -> WebDriverResult<MarionettePrintPage> {
+        Ok(MarionettePrintPage {
+            width: self.width,
+            height: self.height,
+        })
+    }
+}
+
+impl ToMarionette<MarionettePrintMargins> for PrintMargins {
+    fn to_marionette(&self) -> WebDriverResult<MarionettePrintMargins> {
+        Ok(MarionettePrintMargins {
+            top: self.top,
+            bottom: self.bottom,
+            left: self.left,
+            right: self.right,
+        })
+    }
+}
+
+impl ToMarionette<Map<String, Value>> for ActionsParameters {
+    fn to_marionette(&self) -> WebDriverResult<Map<String, Value>> {
+        Ok(try_opt!(
+            serde_json::to_value(self)?.as_object(),
+            ErrorStatus::UnknownError,
+            "Expected an object"
+        )
+        .clone())
+    }
+}
+
+impl ToMarionette<MarionetteCookie> for AddCookieParameters {
+    fn to_marionette(&self) -> WebDriverResult<MarionetteCookie> {
+        Ok(MarionetteCookie {
+            name: self.name.clone(),
+            value: self.value.clone(),
+            path: self.path.clone(),
+            domain: self.domain.clone(),
+            secure: self.secure,
+            http_only: self.httpOnly,
+            expiry: match &self.expiry {
+                Some(date) => Some(date.to_marionette()?),
+                None => None,
+            },
+            same_site: self.sameSite.clone(),
+        })
+    }
+}
+
+impl ToMarionette<MarionetteDate> for Date {
+    fn to_marionette(&self) -> WebDriverResult<MarionetteDate> {
+        Ok(MarionetteDate(self.0))
+    }
+}
+
+impl ToMarionette<Map<String, Value>> for GetNamedCookieParameters {
+    fn to_marionette(&self) -> WebDriverResult<Map<String, Value>> {
+        Ok(try_opt!(
+            serde_json::to_value(self)?.as_object(),
+            ErrorStatus::UnknownError,
+            "Expected an object"
+        )
+        .clone())
+    }
+}
+
+impl ToMarionette<MarionetteUrl> for GetParameters {
+    fn to_marionette(&self) -> WebDriverResult<MarionetteUrl> {
+        Ok(MarionetteUrl {
+            url: self.url.clone(),
+        })
+    }
+}
+
+impl ToMarionette<MarionetteScript> for JavascriptCommandParameters {
+    fn to_marionette(&self) -> WebDriverResult<MarionetteScript> {
+        Ok(MarionetteScript {
+            script: self.script.clone(),
+            args: self.args.clone(),
+        })
+    }
+}
+
+impl ToMarionette<MarionetteLocator> for LocatorParameters {
+    fn to_marionette(&self) -> WebDriverResult<MarionetteLocator> {
+        Ok(MarionetteLocator {
+            using: self.using.to_marionette()?,
+            value: self.value.clone(),
+        })
+    }
+}
+
+impl ToMarionette<MarionetteSelector> for LocatorStrategy {
+    fn to_marionette(&self) -> WebDriverResult<MarionetteSelector> {
+        use self::LocatorStrategy::*;
+        match self {
+            CSSSelector => Ok(MarionetteSelector::CSS),
+            LinkText => Ok(MarionetteSelector::LinkText),
+            PartialLinkText => Ok(MarionetteSelector::PartialLinkText),
+            TagName => Ok(MarionetteSelector::TagName),
+            XPath => Ok(MarionetteSelector::XPath),
+        }
+    }
+}
+
+impl ToMarionette<MarionetteNewWindow> for NewWindowParameters {
+    fn to_marionette(&self) -> WebDriverResult<MarionetteNewWindow> {
+        Ok(MarionetteNewWindow {
+            type_hint: self.type_hint.clone(),
+        })
+    }
+}
+
+impl ToMarionette<MarionetteKeys> for SendKeysParameters {
+    fn to_marionette(&self) -> WebDriverResult<MarionetteKeys> {
+        Ok(MarionetteKeys {
+            text: self.text.clone(),
+            value: self
+                .text
+                .chars()
+                .map(|x| x.to_string())
+                .collect::<Vec<String>>(),
+        })
+    }
+}
+
+impl ToMarionette<MarionetteFrame> for SwitchToFrameParameters {
+    fn to_marionette(&self) -> WebDriverResult<MarionetteFrame> {
+        Ok(match &self.id {
+            Some(x) => match x {
+                FrameId::Short(n) => MarionetteFrame::Index(n.clone()),
+                FrameId::Element(el) => MarionetteFrame::Element(el.0.clone()),
+            },
+            None => MarionetteFrame::Parent,
+        })
+    }
+}
+
+impl ToMarionette<Window> for SwitchToWindowParameters {
+    fn to_marionette(&self) -> WebDriverResult<Window> {
+        Ok(Window {
+            name: self.handle.clone(),
+            handle: self.handle.clone(),
+        })
+    }
+}
+
+impl ToMarionette<MarionetteTimeouts> for TimeoutsParameters {
+    fn to_marionette(&self) -> WebDriverResult<MarionetteTimeouts> {
+        Ok(MarionetteTimeouts {
+            implicit: self.implicit,
+            page_load: self.page_load,
+            script: self.script,
+        })
+    }
+}
+
+impl ToMarionette<LegacyWebElement> for WebElement {
+    fn to_marionette(&self) -> WebDriverResult<LegacyWebElement> {
+        Ok(LegacyWebElement {
+            id: self.to_string(),
+        })
+    }
+}
+
+impl ToMarionette<MarionetteWebElement> for WebElement {
+    fn to_marionette(&self) -> WebDriverResult<MarionetteWebElement> {
+        Ok(MarionetteWebElement {
+            element: self.to_string(),
+        })
+    }
+}
+
+impl ToMarionette<MarionetteWindowRect> for WindowRectParameters {
+    fn to_marionette(&self) -> WebDriverResult<MarionetteWindowRect> {
+        Ok(MarionetteWindowRect {
+            x: self.x,
+            y: self.y,
+            width: self.width,
+            height: self.height,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{MarionetteHandler, MarionetteSettings};
+    use mozprofile::preferences::PrefValue;
+    use mozprofile::profile::Profile;
+
+    // This is not a pretty test, mostly due to the nature of
+    // mozprofile's and MarionetteHandler's APIs, but we have had
+    // several regressions related to marionette.log.level.
+    #[test]
+    fn test_marionette_log_level() {
+        let mut profile = Profile::new().unwrap();
+        let handler = MarionetteHandler::new(MarionetteSettings::default());
+        handler.set_prefs(2828, &mut profile, false, vec![]).ok();
+        let user_prefs = profile.user_prefs().unwrap();
+
+        let pref = user_prefs.get("marionette.log.level").unwrap();
+        let value = match pref.value {
+            PrefValue::String(ref s) => s,
+            _ => panic!(),
+        };
+        for (i, ch) in value.chars().enumerate() {
+            if i == 0 {
+                assert!(ch.is_uppercase());
+            } else {
+                assert!(ch.is_lowercase());
+            }
+        }
+    }
+}
diff --git a/testing/geckodriver/src/prefs.rs b/testing/geckodriver/src/prefs.rs
new file mode 100644
index 0000000000..075d0c6809
--- /dev/null
+++ b/testing/geckodriver/src/prefs.rs
@@ -0,0 +1,160 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use mozprofile::preferences::Pref;
+
+// ALL CHANGES TO THIS FILE MUST HAVE REVIEW FROM A GECKODRIVER PEER!
+//
+// All preferences in this file are not immediately effective, and
+// require a restart of Firefox, or have to be set in the profile before
+// Firefox gets started the first time. If a preference has to be added,
+// which is immediately effective, it needs to be done in Marionette
+// (marionette.js).
+//
+// Note: geckodriver is used out-of-tree with various builds of Firefox.
+// Removing a preference from this file will cause regressions,
+// so please be careful and get review from a Testing :: geckodriver peer
+// before you make any changes to this file.
+lazy_static! {
+    pub static ref DEFAULT: Vec<(&'static str, Pref)> = vec![
+        // Make sure Shield doesn't hit the network.
+        ("app.normandy.api_url", Pref::new("")),
+
+        // Disable Firefox old build background check
+        ("app.update.checkInstallTime", Pref::new(false)),
+
+        // Disable automatically upgrading Firefox
+        //
+        // Note: Possible update tests could reset or flip the value to allow
+        // updates to be downloaded and applied.
+        ("app.update.disabledForTesting", Pref::new(true)),
+        // !!! For backward compatibility up to Firefox 64. Only remove
+        // when this Firefox version is no longer supported by geckodriver !!!
+        ("app.update.auto", Pref::new(false)),
+
+        // Enable the dump function, which sends messages to the system
+        // console
+        ("browser.dom.window.dump.enabled", Pref::new(true)),
+        ("devtools.console.stdout.chrome", Pref::new(true)),
+
+        // Disable safebrowsing components
+        ("browser.safebrowsing.blockedURIs.enabled", Pref::new(false)),
+        ("browser.safebrowsing.downloads.enabled", Pref::new(false)),
+        ("browser.safebrowsing.passwords.enabled", Pref::new(false)),
+        ("browser.safebrowsing.malware.enabled", Pref::new(false)),
+        ("browser.safebrowsing.phishing.enabled", Pref::new(false)),
+
+        // Do not restore the last open set of tabs if the browser crashed
+        ("browser.sessionstore.resume_from_crash", Pref::new(false)),
+
+        // Skip check for default browser on startup
+        ("browser.shell.checkDefaultBrowser", Pref::new(false)),
+
+        // Do not redirect user when a milestone upgrade of Firefox
+        // is detected
+        ("browser.startup.homepage_override.mstone", Pref::new("ignore")),
+
+        // Start with a blank page (about:blank)
+        ("browser.startup.page", Pref::new(0)),
+
+        // Do not close the window when the last tab gets closed
+        // TODO: Remove once minimum supported Firefox release is 61.
+        ("browser.tabs.closeWindowWithLastTab", Pref::new(false)),
+
+        // Do not warn when closing all open tabs
+        // TODO: Remove once minimum supported Firefox release is 61.
+        ("browser.tabs.warnOnClose", Pref::new(false)),
+
+        // Disable the UI tour
+        ("browser.uitour.enabled", Pref::new(false)),
+
+        // Do not warn on quitting Firefox
+        ("browser.warnOnQuit", Pref::new(false)),
+
+        // Defensively disable data reporting systems
+        ("datareporting.healthreport.documentServerURI", Pref::new("http://%(server)s/dummy/healthreport/")),
+        ("datareporting.healthreport.logging.consoleEnabled", Pref::new(false)),
+        ("datareporting.healthreport.service.enabled", Pref::new(false)),
+        ("datareporting.healthreport.service.firstRun", Pref::new(false)),
+        ("datareporting.healthreport.uploadEnabled", Pref::new(false)),
+
+        // Do not show datareporting policy notifications which can
+        // interfere with tests
+        ("datareporting.policy.dataSubmissionEnabled", Pref::new(false)),
+        ("datareporting.policy.dataSubmissionPolicyBypassNotification", Pref::new(true)),
+
+        // Disable the ProcessHangMonitor
+        ("dom.ipc.reportProcessHangs", Pref::new(false)),
+
+        // Only load extensions from the application and user profile
+        // AddonManager.SCOPE_PROFILE + AddonManager.SCOPE_APPLICATION
+        ("extensions.autoDisableScopes", Pref::new(0)),
+        ("extensions.enabledScopes", Pref::new(5)),
+
+        // Disable intalling any distribution extensions or add-ons
+        ("extensions.installDistroAddons", Pref::new(false)),
+
+        // Turn off extension updates so they do not bother tests
+        ("extensions.update.enabled", Pref::new(false)),
+        ("extensions.update.notifyUser", Pref::new(false)),
+
+        // Allow the application to have focus even it runs in the
+        // background
+        ("focusmanager.testmode", Pref::new(true)),
+
+        // Disable useragent updates
+        ("general.useragent.updates.enabled", Pref::new(false)),
+
+        // Always use network provider for geolocation tests so we bypass
+        // the macOS dialog raised by the corelocation provider
+        ("geo.provider.testing", Pref::new(true)),
+
+        // Do not scan wi-fi
+        ("geo.wifi.scan", Pref::new(false)),
+
+        // No hang monitor
+        ("hangmonitor.timeout", Pref::new(0)),
+
+        // Disable idle-daily notifications to avoid expensive operations
+        // that may cause unexpected test timeouts.
+        ("idle.lastDailyNotification", Pref::new(-1)),
+
+        // Show chrome errors and warnings in the error console
+        ("javascript.options.showInConsole", Pref::new(true)),
+
+        // Disable download and usage of OpenH264, and Widevine plugins
+        ("media.gmp-manager.updateEnabled", Pref::new(false)),
+
+        // Disable the GFX sanity window
+        ("media.sanity-test.disabled", Pref::new(true)),
+
+        // Do not prompt with long usernames or passwords in URLs
+        // TODO: Remove once minimum supported Firefox release is 61.
+        ("network.http.phishy-userpass-length", Pref::new(255)),
+
+        // Do not automatically switch between offline and online
+        ("network.manage-offline-status", Pref::new(false)),
+
+        // Make sure SNTP requests do not hit the network
+        ("network.sntp.pools", Pref::new("%(server)s")),
+
+        // Disable Flash.  The plugin container it is run in is
+        // causing problems when quitting Firefox from geckodriver,
+        // c.f. https://github.com/mozilla/geckodriver/issues/225.
+        ("plugin.state.flash", Pref::new(0)),
+
+        // Don't do network connections for mitm priming
+        ("security.certerrors.mitm.priming.enabled", Pref::new(false)),
+
+        // Ensure blocklist updates don't hit the network
+        ("services.settings.server", Pref::new("http://%(server)s/dummy/blocklist/")),
+
+        // Disable first run pages
+        ("startup.homepage_welcome_url", Pref::new("about:blank")),
+        ("startup.homepage_welcome_url.additional", Pref::new("")),
+
+        // Prevent starting into safe mode after application crashes
+        ("toolkit.startup.max_resumed_crashes", Pref::new(-1)),
+    ];
+}
diff --git a/testing/geckodriver/src/test.rs b/testing/geckodriver/src/test.rs
new file mode 100644
index 0000000000..e664aadf08
--- /dev/null
+++ b/testing/geckodriver/src/test.rs
@@ -0,0 +1,12 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+pub fn assert_de<T>(data: &T, json: serde_json::Value)
+where
+    T: std::fmt::Debug,
+    T: std::cmp::PartialEq,
+    T: serde::de::DeserializeOwned,
+{
+    assert_eq!(data, &serde_json::from_value::<T>(json).unwrap());
+}
diff --git a/testing/geckodriver/src/tests/profile.zip b/testing/geckodriver/src/tests/profile.zip
new file mode 100644
index 0000000000..286b118183
--- /dev/null
+++ b/testing/geckodriver/src/tests/profile.zip