feat: Use test name for dir when running tests

Muscraft · Muscraft · commit cbdfb3e2a561 · 2025-11-18T07:20:03.000-07:00
diff --git a/crates/cargo-test-macro/src/lib.rs b/crates/cargo-test-macro/src/lib.rs
@@ -200,6 +200,9 @@ pub fn cargo_test(attr: TokenStream, item: TokenStream) -> TokenStream {
         add_attr(&mut ret, "ignore", reason);
     }
 
+    let mut test_name = None;
+    let mut num = 0;
+
     // Find where the function body starts, and add the boilerplate at the start.
     for token in item {
         let group = match token {
@@ -211,18 +214,44 @@ pub fn cargo_test(attr: TokenStream, item: TokenStream) -> TokenStream {
                     continue;
                 }
             }
+            TokenTree::Ident(i) => {
+                // The first time through it will be `fn` the second time is the
+                // name of the test.
+                if test_name.is_none() && num == 1 {
+                    test_name = Some(i.to_string())
+                } else {
+                    num += 1;
+                }
+                ret.extend(Some(TokenTree::Ident(i)));
+                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)
-            };"#,
-        );
+        let name = &test_name
+            .clone()
+            .map(|n| n.split("::").next().unwrap().to_string())
+            .unwrap();
+
+        let mut new_body = if cfg!(windows) {
+            to_token_stream(
+                r#"let _test_guard = {
+                    let tmp_dir = option_env!("CARGO_TARGET_TMPDIR");
+                    cargo_test_support::paths::init_root(tmp_dir)
+                };"#,
+            )
+        } else {
+            to_token_stream(&format!(
+                r#"let _test_guard = {{
+                    let tmp_dir = option_env!("CARGO_TARGET_TMPDIR");
+                    let test_dir = cargo_test_support::paths::test_dir(std::file!(), "{name}");
+                cargo_test_support::paths::init_root(tmp_dir, test_dir)
+            }};"#
+            ))
+        };
 
         new_body.extend(group.stream());
         ret.extend(Some(TokenTree::from(Group::new(
diff --git a/crates/cargo-test-support/src/paths.rs b/crates/cargo-test-support/src/paths.rs
@@ -62,16 +62,15 @@ pub fn global_root() -> PathBuf {
     }
 }
 
-// We need to give each test a unique id. The test name could serve this
-// purpose, but the `test` crate doesn't have a way to obtain the current test
-// name.[*] Instead, we used the `cargo-test-macro` crate to automatically
-// insert an init function for each test that sets the test name in a thread
-// local variable.
-//
-// [*] It does set the thread name, but only when running concurrently. If not
-// running concurrently, all tests are run on the main thread.
+// We need to give each test a unique id. The test name serve this
+// purpose. We are able to get the test name by having the `cargo-test-macro`
+// crate automatically insert an init function for each test that sets the
+// test name in a thread local variable.
 thread_local! {
+    #[cfg(windows)]
     static TEST_ID: RefCell<Option<usize>> = const { RefCell::new(None) };
+    #[cfg(not(windows))]
+    static TEST_NAME: RefCell<Option<PathBuf>> = const { RefCell::new(None) };
 }
 
 /// See [`init_root`]
@@ -80,31 +79,58 @@ pub struct TestIdGuard {
 }
 
 /// For test harnesses like [`crate::cargo_test`]
+#[cfg(windows)]
 pub fn init_root(tmp_dir: Option<&'static str>) -> TestIdGuard {
     static NEXT_ID: AtomicUsize = AtomicUsize::new(0);
 
     let id = NEXT_ID.fetch_add(1, Ordering::SeqCst);
     TEST_ID.with(|n| *n.borrow_mut() = Some(id));
+    let guard = TestIdGuard { _private: () };
+
+    set_global_root(tmp_dir);
+    let r = root();
+    r.rm_rf();
+    r.mkdir_p();
+
+    guard
+}
+
+/// For test harnesses like [`crate::cargo_test`]
+#[cfg(not(windows))]
+pub fn init_root(tmp_dir: Option<&'static str>, test_name: PathBuf) -> TestIdGuard {
+    static NEXT_ID: AtomicUsize = AtomicUsize::new(0);
+    let id = NEXT_ID.fetch_add(1, Ordering::SeqCst);
 
+    TEST_NAME.with(|n| *n.borrow_mut() = Some(test_name));
     let guard = TestIdGuard { _private: () };
 
     set_global_root(tmp_dir);
     let r = root();
     r.rm_rf();
     r.mkdir_p();
+    if id == 0 {
+        use crate::SymlinkBuilder;
 
+        let mut root = global_root();
+        root.push(&format!("t{}", id));
+        SymlinkBuilder::new_dir(r, root).mk();
+    }
     guard
 }
 
 impl Drop for TestIdGuard {
     fn drop(&mut self) {
+        #[cfg(windows)]
         TEST_ID.with(|n| *n.borrow_mut() = None);
+        #[cfg(not(windows))]
+        TEST_NAME.with(|n| *n.borrow_mut() = None);
     }
 }
 
 /// Path to the test's filesystem scratchpad
 ///
 /// ex: `$CARGO_TARGET_TMPDIR/cit/t0`
+#[cfg(windows)]
 pub fn root() -> PathBuf {
     let id = TEST_ID.with(|n| {
         n.borrow().expect(
@@ -118,6 +144,23 @@ pub fn root() -> PathBuf {
     root
 }
 
+/// Path to the test's filesystem scratchpad
+///
+/// ex: `$CARGO_TARGET_TMPDIR/cit/t0`
+#[cfg(not(windows))]
+pub fn root() -> PathBuf {
+    let test_name = TEST_NAME.with(|n| {
+        n.borrow().clone().expect(
+            "Tests must use the `#[cargo_test]` attribute in \
+             order to be able to use the crate root.",
+        )
+    });
+
+    let mut root = global_root();
+    root.push(&test_name);
+    root
+}
+
 /// Path to the current test's `$HOME`
 ///
 /// ex: `$CARGO_TARGET_TMPDIR/cit/t0/home`
@@ -489,3 +532,26 @@ pub fn windows_reserved_names_are_allowed() -> bool {
         true
     }
 }
+
+/// This takes the test location (std::file!() should be passed) and the test name
+/// and outputs the location the test should be places in, inside of `target/tmp/cit`
+///
+/// `path: tests/testsuite/workspaces.rs`
+/// `name: `workspace_in_git
+/// `output: "testsuite/workspaces/workspace_in_git`
+pub fn test_dir(path: &str, name: &str) -> std::path::PathBuf {
+    let test_dir: std::path::PathBuf = std::path::PathBuf::from(path)
+        .components()
+        // Trim .rs from any files
+        .map(|c| c.as_os_str().to_str().unwrap().trim_end_matches(".rs"))
+        // We only want to take once we have reached `tests` or `src`. This helps when in a
+        // workspace: `workspace/more/src/...` would result in `src/...`
+        .skip_while(|c| c != &"tests" && c != &"src")
+        // We want to skip "tests" since it is taken in `skip_while`.
+        // "src" is fine since you could have test in "src" named the same as one in "tests"
+        // Skip "mod" since `snapbox` tests have a folder per test not a file and the files
+        // are named "mod.rs"
+        .filter(|c| c != &"tests" && c != &"mod")
+        .collect();
+    test_dir.join(name)
+}
diff --git a/src/doc/contrib/src/tests/writing.md b/src/doc/contrib/src/tests/writing.md
@@ -200,8 +200,10 @@ Then populate
 - This is used in place of `#[test]`
 - This attribute injects code which does some setup before starting the
   test, creating a filesystem "sandbox" under the "cargo integration test"
-  directory for each test such as
-  `/path/to/cargo/target/cit/t123/`
+  directory for each test. The directory for each test is based on the
+  integration test name, module (if there is one), and function name[^1]:
+
+  `/path/to/cargo/target/tmp/cit/<integration test>/<module>/<fn name>/`
 - The sandbox will contain a `home` directory that will be used instead of your normal home directory
 
 `Project`:
@@ -258,6 +260,11 @@ or overwrite a binary immediately after running it. Under some conditions
 Windows will fail with errors like "directory not empty" or "failed to remove"
 or "access is denied".
 
+On Windows, to avoid path length limitations, the tests use the following
+directory structure instead:
+
+`/path/to/cargo/target/tmp/cit/t123/`
+
 ## Debugging tests
 
 In some cases, you may need to dig into a test that is not working as you
@@ -299,3 +306,6 @@ environment. The general process is:
 [`Command`]: https://docs.rs/snapbox/latest/snapbox/cmd/struct.Command.html
 [`OutputAssert`]: https://docs.rs/snapbox/latest/snapbox/cmd/struct.OutputAssert.html
 [`Assert`]: https://docs.rs/snapbox/latest/snapbox/struct.Assert.html
+
+[^1]: Windows uses a separate directory layout, see [Platform-Specific Notes](#platform-specific-notes)
+    for more details.
diff --git a/tests/testsuite/main.rs b/tests/testsuite/main.rs
@@ -209,3 +209,52 @@ fn aaa_trigger_cross_compile_disabled_check() {
     // This triggers the cross compile disabled check to run ASAP, see #5141
     crate::utils::cross_compile::disabled();
 }
+
+// This is placed here as running tests in `cargo-test-support` would rebuild it
+#[cargo_test]
+#[cfg(not(windows))]
+fn check_test_dir() {
+    let tests = vec![
+        (
+            "tests/testsuite/workspaces.rs",
+            "workspace_in_git",
+            "testsuite/workspaces/workspace_in_git",
+        ),
+        (
+            "tests/testsuite/cargo_remove/invalid_arg/mod.rs",
+            "case",
+            "testsuite/cargo_remove/invalid_arg/case",
+        ),
+        (
+            "tests/build-std/main.rs",
+            "cross_custom",
+            "build-std/main/cross_custom",
+        ),
+        (
+            "src/tools/cargo/tests/testsuite/build.rs",
+            "cargo_compile_simple",
+            "src/tools/cargo/testsuite/build/cargo_compile_simple",
+        ),
+        (
+            "src/tools/cargo/tests/testsuite/cargo_add/add_basic/mod.rs",
+            "case",
+            "src/tools/cargo/testsuite/cargo_add/add_basic/case",
+        ),
+        (
+            "src/tools/cargo/tests/build-std/main.rs",
+            "cross_custom",
+            "src/tools/cargo/build-std/main/cross_custom",
+        ),
+        (
+            "workspace/more/src/tools/cargo/tests/testsuite/build.rs",
+            "cargo_compile_simple",
+            "src/tools/cargo/testsuite/build/cargo_compile_simple",
+        ),
+    ];
+    for (path, name, expected) in tests {
+        assert_eq!(
+            cargo_test_support::paths::test_dir(path, name),
+            std::path::PathBuf::from(expected)
+        );
+    }
+}
