1 files changed, 275 insertions, 0 deletions
diff --git a/third_party/rust/uniffi_testing/src/lib.rs b/third_party/rust/uniffi_testing/src/lib.rs
new file mode 100644
index 0000000000..cc08895214
--- /dev/null
+++ b/third_party/rust/uniffi_testing/src/lib.rs
@@ -0,0 +1,275 @@
+/* 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 anyhow::{bail, Result};
+use camino::{Utf8Path, Utf8PathBuf};
+use cargo_metadata::{Message, Metadata, MetadataCommand, Package, Target};
+use fs_err as fs;
+use once_cell::sync::Lazy;
+use serde::Deserialize;
+use std::{
+    collections::hash_map::DefaultHasher,
+    env,
+    env::consts::DLL_EXTENSION,
+    hash::{Hash, Hasher},
+    process::{Command, Stdio},
+};
+
+#[derive(Debug, Deserialize)]
+struct UniFFITestingMetadata {
+    /// Crates that hold external types used by this crate.  When running the tests, we will build
+    /// the libraries and generate the source files for those crates and put them in the test
+    /// directory
+    #[serde(rename = "external-crates")]
+    external_crates: Option<Vec<String>>,
+}
+
+// A source to compile for a test
+#[derive(Debug)]
+pub struct CompileSource {
+    pub udl_path: Utf8PathBuf,
+    pub config_path: Option<Utf8PathBuf>,
+}
+
+// Store Cargo output to in a static to avoid calling it more than once.
+
+static CARGO_METADATA: Lazy<Metadata> = Lazy::new(get_cargo_metadata);
+static CARGO_BUILD_MESSAGES: Lazy<Vec<Message>> = Lazy::new(get_cargo_build_messages);
+
+/// Struct for running fixture and example tests for bindings generators
+///
+/// Expectations:
+///   - Used from a integration test (a `.rs` file in the tests/ directory)
+///   - The working directory is the project root for the bindings crate. This is the normal case
+///     for test code, just make sure you don't cd somewhere else.
+///   - The bindings crate has a dev-dependency on the fixture crate
+///   - The fixture crate produces a cdylib library
+///   - The fixture crate, and any external-crates, has 1 UDL file in it's src/ directory
+pub struct UniFFITestHelper {
+    name: String,
+    package: Package,
+    metadata: Option<UniFFITestingMetadata>,
+}
+
+impl UniFFITestHelper {
+    pub fn new(name: &str) -> Result<Self> {
+        let package = Self::find_package(name)?;
+        let metadata: Option<UniFFITestingMetadata> = package
+            .metadata
+            .pointer("/uniffi/testing")
+            .cloned()
+            .map(serde_json::from_value)
+            .transpose()?;
+        Ok(Self {
+            name: name.to_string(),
+            package,
+            metadata,
+        })
+    }
+
+    fn find_package(name: &str) -> Result<Package> {
+        let matching: Vec<&Package> = CARGO_METADATA
+            .packages
+            .iter()
+            .filter(|p| p.name == name)
+            .collect();
+        match matching.len() {
+            1 => Ok(matching[0].clone()),
+            n => bail!("cargo metadata return {n} packages named {name}"),
+        }
+    }
+
+    fn find_packages_for_external_crates(&self) -> Result<Vec<Package>> {
+        // Add any external crates listed in `Cargo.toml`
+        match &self.metadata {
+            None => Ok(vec![]),
+            Some(metadata) => metadata
+                .external_crates
+                .iter()
+                .flatten()
+                .map(|name| Self::find_package(name))
+                .collect(),
+        }
+    }
+
+    fn find_cdylib_path(package: &Package) -> Result<Utf8PathBuf> {
+        let cdylib_targets: Vec<&Target> = package
+            .targets
+            .iter()
+            .filter(|t| t.crate_types.iter().any(|t| t == "cdylib"))
+            .collect();
+        let target = match cdylib_targets.len() {
+            1 => cdylib_targets[0],
+            n => bail!("Found {n} cdylib targets for {}", package.name),
+        };
+
+        let artifacts = CARGO_BUILD_MESSAGES
+            .iter()
+            .filter_map(|message| match message {
+                Message::CompilerArtifact(artifact) => {
+                    if artifact.target == *target {
+                        Some(artifact.clone())
+                    } else {
+                        None
+                    }
+                }
+                _ => None,
+            });
+        let cdylib_files: Vec<Utf8PathBuf> = artifacts
+            .into_iter()
+            .flat_map(|artifact| {
+                artifact
+                    .filenames
+                    .into_iter()
+                    .filter(|nm| matches!(nm.extension(), Some(DLL_EXTENSION)))
+                    .collect::<Vec<Utf8PathBuf>>()
+            })
+            .collect();
+
+        match cdylib_files.len() {
+            1 => Ok(cdylib_files[0].to_owned()),
+            n => bail!("Found {n} cdylib files for {}", package.name),
+        }
+    }
+
+    /// Create at `out_dir` for testing
+    ///
+    /// This directory can be used for:
+    ///   - Generated bindings files (usually via the `--out-dir` param)
+    ///   - cdylib libraries that the bindings depend on
+    ///   - Anything else that's useful for testing
+    ///
+    /// This directory typically created as a subdirectory of `CARGO_TARGET_TMPDIR` when running an
+    /// integration test.
+    ///
+    /// We use the script path to create a hash included in the outpuit directory.  This avoids
+    /// path collutions when 2 scripts run against the same fixture.
+    pub fn create_out_dir(
+        &self,
+        temp_dir: impl AsRef<Utf8Path>,
+        script_path: impl AsRef<Utf8Path>,
+    ) -> Result<Utf8PathBuf> {
+        let dirname = format!("{}-{}", self.name, hash_path(script_path.as_ref()));
+        let out_dir = temp_dir.as_ref().join(dirname);
+        if out_dir.exists() {
+            // Clean out any files from previous runs
+            fs::remove_dir_all(&out_dir)?;
+        }
+        fs::create_dir(&out_dir)?;
+        Ok(out_dir)
+    }
+
+    /// Copy the `cdylib` for a fixture into the out_dir
+    ///
+    /// This is typically needed for the bindings to open it when running the tests
+    ///
+    /// Returns the path to the copied library
+    pub fn copy_cdylibs_to_out_dir(&self, out_dir: impl AsRef<Utf8Path>) -> Result<()> {
+        let cdylib_paths =
+            std::iter::once(self.cdylib_path()?).chain(self.external_cdylib_paths()?);
+
+        for path in cdylib_paths {
+            let dest = out_dir.as_ref().join(path.file_name().unwrap());
+            fs::copy(&path, dest)?;
+        }
+        Ok(())
+    }
+
+    /// Get the path to the cdylib file for this package
+    pub fn cdylib_path(&self) -> Result<Utf8PathBuf> {
+        Self::find_cdylib_path(&self.package)
+    }
+
+    /// Get the path to the cdylib file for external crates listed in `Cargo.toml`
+    pub fn external_cdylib_paths(&self) -> Result<Vec<Utf8PathBuf>> {
+        self.find_packages_for_external_crates()?
+            .into_iter()
+            .map(|p| Self::find_cdylib_path(&p))
+            .collect()
+    }
+
+    /// Get paths to the UDL and config files for a fixture
+    pub fn get_compile_sources(&self) -> Result<Vec<CompileSource>> {
+        Ok(std::iter::once(self.get_main_compile_source()?)
+            .chain(self.get_external_compile_sources()?)
+            .collect())
+    }
+
+    pub fn get_main_compile_source(&self) -> Result<CompileSource> {
+        self.find_compile_source(&self.package.clone())
+    }
+
+    pub fn get_external_compile_sources(&self) -> Result<Vec<CompileSource>> {
+        self.find_packages_for_external_crates()?
+            .into_iter()
+            .map(|p| self.find_compile_source(&p))
+            .collect()
+    }
+
+    fn find_compile_source(&self, package: &Package) -> Result<CompileSource> {
+        let crate_root = package.manifest_path.parent().unwrap();
+        let src_dir = crate_root.join("src");
+        let mut udl_paths = find_files(
+            &src_dir,
+            |path| matches!(path.extension(), Some(ext) if ext.to_ascii_lowercase() == "udl"),
+        )?;
+        let udl_path = match udl_paths.len() {
+            1 => udl_paths.remove(0),
+            n => bail!("Found {n} UDL files in {src_dir}"),
+        };
+        let mut config_paths = find_files(
+            crate_root,
+            |path| matches!(path.file_name(), Some(name) if name == "uniffi.toml"),
+        )?;
+        let config_path = match config_paths.len() {
+            0 => None,
+            1 => Some(config_paths.remove(0)),
+            n => bail!("Found {n} UDL files in {crate_root}"),
+        };
+
+        Ok(CompileSource {
+            udl_path,
+            config_path,
+        })
+    }
+}
+
+fn find_files<F: Fn(&Utf8Path) -> bool>(dir: &Utf8Path, predicate: F) -> Result<Vec<Utf8PathBuf>> {
+    fs::read_dir(dir)?
+        .flatten()
+        .map(|entry| entry.path().try_into())
+        .try_fold(Vec::new(), |mut vec, path| {
+            let path: Utf8PathBuf = path?;
+            if predicate(&path) {
+                vec.push(path);
+            }
+            Ok(vec)
+        })
+}
+
+fn get_cargo_metadata() -> Metadata {
+    MetadataCommand::new()
+        .exec()
+        .expect("error running cargo metadata")
+}
+
+fn get_cargo_build_messages() -> Vec<Message> {
+    let mut child = Command::new(env!("CARGO"))
+        .arg("build")
+        .arg("--message-format=json")
+        .arg("--tests")
+        .stdout(Stdio::piped())
+        .spawn()
+        .expect("Error running cargo build");
+    let output = std::io::BufReader::new(child.stdout.take().unwrap());
+    Message::parse_stream(output)
+        .map(|m| m.expect("Error parsing cargo build messages"))
+        .collect()
+}
+
+fn hash_path(path: &Utf8Path) -> String {
+    let mut hasher = DefaultHasher::new();
+    path.hash(&mut hasher);
+    format!("{:x}", hasher.finish())
+}