1 files changed, 245 insertions, 0 deletions
diff --git a/crates/cargo-test-macro/src/lib.rs b/crates/cargo-test-macro/src/lib.rs
new file mode 100644
index 0000000..aa06f47
--- /dev/null
+++ b/crates/cargo-test-macro/src/lib.rs
@@ -0,0 +1,245 @@
+extern crate proc_macro;
+
+use proc_macro::*;
+use std::process::Command;
+use std::sync::Once;
+
+#[proc_macro_attribute]
+pub fn cargo_test(attr: TokenStream, item: TokenStream) -> TokenStream {
+    // Ideally these options would be embedded in the test itself. However, I
+    // find it very helpful to have the test clearly state whether or not it
+    // is ignored. It would be nice to have some kind of runtime ignore
+    // support (such as
+    // https://internals.rust-lang.org/t/pre-rfc-skippable-tests/14611).
+    //
+    // Unfortunately a big drawback here is that if the environment changes
+    // (such as the existence of the `git` CLI), this will not trigger a
+    // rebuild and the test will still be ignored. In theory, something like
+    // `tracked_env` or `tracked_path`
+    // (https://github.com/rust-lang/rust/issues/99515) could help with this,
+    // but they don't really handle the absence of files well.
+    let mut ignore = false;
+    let mut requires_reason = false;
+    let mut explicit_reason = None;
+    let mut implicit_reasons = Vec::new();
+    macro_rules! set_ignore {
+        ($predicate:expr, $($arg:tt)*) => {
+            let p = $predicate;
+            ignore |= p;
+            if p {
+                implicit_reasons.push(std::fmt::format(format_args!($($arg)*)));
+            }
+        };
+    }
+    let is_not_nightly = !version().1;
+    for rule in split_rules(attr) {
+        match rule.as_str() {
+            "build_std_real" => {
+                // Only run the "real" build-std tests on nightly and with an
+                // explicit opt-in (these generally only work on linux, and
+                // have some extra requirements, and are slow, and can pollute
+                // the environment since it downloads dependencies).
+                set_ignore!(is_not_nightly, "requires nightly");
+                set_ignore!(
+                    option_env!("CARGO_RUN_BUILD_STD_TESTS").is_none(),
+                    "CARGO_RUN_BUILD_STD_TESTS must be set"
+                );
+            }
+            "build_std_mock" => {
+                // Only run the "mock" build-std tests on nightly and disable
+                // for windows-gnu which is missing object files (see
+                // https://github.com/rust-lang/wg-cargo-std-aware/issues/46).
+                set_ignore!(is_not_nightly, "requires nightly");
+                set_ignore!(
+                    cfg!(all(target_os = "windows", target_env = "gnu")),
+                    "does not work on windows-gnu"
+                );
+            }
+            "container_test" => {
+                // These tests must be opt-in because they require docker.
+                set_ignore!(
+                    option_env!("CARGO_CONTAINER_TESTS").is_none(),
+                    "CARGO_CONTAINER_TESTS must be set"
+                );
+            }
+            "public_network_test" => {
+                // These tests must be opt-in because they touch the public
+                // network. The use of these should be **EXTREMELY RARE**, and
+                // should only touch things which would nearly certainly work
+                // in CI (like github.com).
+                set_ignore!(
+                    option_env!("CARGO_PUBLIC_NETWORK_TESTS").is_none(),
+                    "CARGO_PUBLIC_NETWORK_TESTS must be set"
+                );
+            }
+            "nightly" => {
+                requires_reason = true;
+                set_ignore!(is_not_nightly, "requires nightly");
+            }
+            s if s.starts_with("requires_") => {
+                let command = &s[9..];
+                set_ignore!(!has_command(command), "{command} not installed");
+            }
+            s if s.starts_with(">=1.") => {
+                requires_reason = true;
+                let min_minor = s[4..].parse().unwrap();
+                let minor = version().0;
+                set_ignore!(minor < min_minor, "requires rustc 1.{minor} or newer");
+            }
+            s if s.starts_with("reason=") => {
+                explicit_reason = Some(s[7..].parse().unwrap());
+            }
+            s if s.starts_with("ignore_windows=") => {
+                set_ignore!(cfg!(windows), "{}", &s[16..s.len() - 1]);
+            }
+            _ => panic!("unknown rule {:?}", rule),
+        }
+    }
+    if requires_reason && explicit_reason.is_none() {
+        panic!(
+            "#[cargo_test] with a rule also requires a reason, \
+            such as #[cargo_test(nightly, reason = \"needs -Z unstable-thing\")]"
+        );
+    }
+
+    // Construct the appropriate attributes.
+    let span = Span::call_site();
+    let mut ret = TokenStream::new();
+    let add_attr = |ret: &mut TokenStream, attr_name, attr_input| {
+        ret.extend(Some(TokenTree::from(Punct::new('#', Spacing::Alone))));
+        let attr = TokenTree::from(Ident::new(attr_name, span));
+        let mut attr_stream: TokenStream = attr.into();
+        if let Some(input) = attr_input {
+            attr_stream.extend(input);
+        }
+        ret.extend(Some(TokenTree::from(Group::new(
+            Delimiter::Bracket,
+            attr_stream,
+        ))));
+    };
+    add_attr(&mut ret, "test", None);
+    if ignore {
+        let reason = explicit_reason
+            .or_else(|| {
+                (!implicit_reasons.is_empty())
+                    .then(|| TokenTree::from(Literal::string(&implicit_reasons.join(", "))).into())
+            })
+            .map(|reason: TokenStream| {
+                let mut stream = TokenStream::new();
+                stream.extend(Some(TokenTree::from(Punct::new('=', Spacing::Alone))));
+                stream.extend(Some(reason));
+                stream
+            });
+        add_attr(&mut ret, "ignore", reason);
+    }
+
+    // Find where the function body starts, and add the boilerplate at the start.
+    for token in item {
+        let group = match token {
+            TokenTree::Group(g) => {
+                if g.delimiter() == Delimiter::Brace {
+                    g
+                } else {
+                    ret.extend(Some(TokenTree::Group(g)));
+                    continue;
+                }
+            }
+            other => {
+                ret.extend(Some(other));
+                continue;
+            }
+        };
+
+        let mut new_body = to_token_stream(
+            r#"let _test_guard = {
+                let tmp_dir = option_env!("CARGO_TARGET_TMPDIR");
+                cargo_test_support::paths::init_root(tmp_dir)
+            };"#,
+        );
+
+        new_body.extend(group.stream());
+        ret.extend(Some(TokenTree::from(Group::new(
+            group.delimiter(),
+            new_body,
+        ))));
+    }
+
+    ret
+}
+
+fn split_rules(t: TokenStream) -> Vec<String> {
+    let tts: Vec<_> = t.into_iter().collect();
+    tts.split(|tt| match tt {
+        TokenTree::Punct(p) => p.as_char() == ',',
+        _ => false,
+    })
+    .filter(|parts| !parts.is_empty())
+    .map(|parts| {
+        parts
+            .into_iter()
+            .map(|part| part.to_string())
+            .collect::<String>()
+    })
+    .collect()
+}
+
+fn to_token_stream(code: &str) -> TokenStream {
+    code.parse().unwrap()
+}
+
+static mut VERSION: (u32, bool) = (0, false);
+
+fn version() -> &'static (u32, bool) {
+    static INIT: Once = Once::new();
+    INIT.call_once(|| {
+        let output = Command::new("rustc")
+            .arg("-V")
+            .output()
+            .expect("rustc should run");
+        let stdout = std::str::from_utf8(&output.stdout).expect("utf8");
+        let vers = stdout.split_whitespace().skip(1).next().unwrap();
+        let is_nightly = option_env!("CARGO_TEST_DISABLE_NIGHTLY").is_none()
+            && (vers.contains("-nightly") || vers.contains("-dev"));
+        let minor = vers.split('.').skip(1).next().unwrap().parse().unwrap();
+        unsafe { VERSION = (minor, is_nightly) }
+    });
+    unsafe { &VERSION }
+}
+
+fn has_command(command: &str) -> bool {
+    let output = match Command::new(command).arg("--version").output() {
+        Ok(output) => output,
+        Err(e) => {
+            // hg is not installed on GitHub macOS or certain constrained
+            // environments like Docker. Consider installing it if Cargo gains
+            // more hg support, but otherwise it isn't critical.
+            if is_ci() && command != "hg" {
+                panic!(
+                    "expected command `{}` to be somewhere in PATH: {}",
+                    command, e
+                );
+            }
+            return false;
+        }
+    };
+    if !output.status.success() {
+        panic!(
+            "expected command `{}` to be runnable, got error {}:\n\
+            stderr:{}\n\
+            stdout:{}\n",
+            command,
+            output.status,
+            String::from_utf8_lossy(&output.stderr),
+            String::from_utf8_lossy(&output.stdout)
+        );
+    }
+    true
+}
+
+/// Whether or not this running in a Continuous Integration environment.
+fn is_ci() -> bool {
+    // Consider using `tracked_env` instead of option_env! when it is stabilized.
+    // `tracked_env` will handle changes, but not require rebuilding the macro
+    // itself like option_env does.
+    option_env!("CI").is_some() || option_env!("TF_BUILD").is_some()
+}