Assert that tests are run in the crate directory

To avoid regressions to the test runtime directory, this asserts that
all test types (unit, integration, doctest) are executed in the crate
(manifest) directory, no matter where that crate is in relation to the
workspace root.

See rust-lang#8992 / rust-lang#8993

tests/testsuite/test.rs

@@ -4245,3 +4245,140 @@ fn bin_env_for_test() {
     p.cargo("test --test check_env").run();
     p.cargo("check --test check_env").run();
 }
+
+#[cargo_test]
+fn test_workspaces_cwd() {
+    // This tests that all the different test types are executed from the
+    // crate directory (manifest_dir), and not from the workspace root.
+
+    let make_lib_file = |expected| {
+        format!(
+            r#"
+                //! ```
+                //! assert_eq!("{expected}", std::fs::read_to_string("file.txt").unwrap());
+                //! assert_eq!(
+                //!     std::path::PathBuf::from(std::env!("CARGO_MANIFEST_DIR")),
+                //!     std::env::current_dir().unwrap(),
+                //! );
+                //! ```
+
+                #[test]
+                fn test_unit_{expected}_cwd() {{
+                    assert_eq!("{expected}", std::fs::read_to_string("file.txt").unwrap());
+                    assert_eq!(
+                        std::path::PathBuf::from(std::env!("CARGO_MANIFEST_DIR")),
+                        std::env::current_dir().unwrap(),
+                    );
+                }}
+            "#,
+            expected = expected
+        )
+    };
+    let make_test_file = |expected| {
+        format!(
+            r#"
+                #[test]
+                fn test_integration_{expected}_cwd() {{
+                    assert_eq!("{expected}", std::fs::read_to_string("file.txt").unwrap());
+                    assert_eq!(
+                        std::path::PathBuf::from(std::env!("CARGO_MANIFEST_DIR")),
+                        std::env::current_dir().unwrap(),
+                    );
+                }}
+            "#,
+            expected = expected
+        )
+    };
+
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "root-crate"
+                version = "0.0.0"
+
+                [workspace]
+                members = [".", "nested-crate", "very/deeply/nested/deep-crate"]
+            "#,
+        )
+        .file("file.txt", "root")
+        .file("src/lib.rs", &make_lib_file("root"))
+        .file("tests/integration.rs", &make_test_file("root"))
+        .file(
+            "nested-crate/Cargo.toml",
+            r#"
+                [package]
+                name = "nested-crate"
+                version = "0.0.0"
+            "#,
+        )
+        .file("nested-crate/file.txt", "nested")
+        .file("nested-crate/src/lib.rs", &make_lib_file("nested"))
+        .file(
+            "nested-crate/tests/integration.rs",
+            &make_test_file("nested"),
+        )
+        .file(
+            "very/deeply/nested/deep-crate/Cargo.toml",
+            r#"
+                [package]
+                name = "deep-crate"
+                version = "0.0.0"
+            "#,
+        )
+        .file("very/deeply/nested/deep-crate/file.txt", "deep")
+        .file(
+            "very/deeply/nested/deep-crate/src/lib.rs",
+            &make_lib_file("deep"),
+        )
+        .file(
+            "very/deeply/nested/deep-crate/tests/integration.rs",
+            &make_test_file("deep"),
+        )
+        .build();
+
+    p.cargo("test --workspace --all")
+        .with_stderr_contains("[DOCTEST] root-crate")
+        .with_stderr_contains("[DOCTEST] nested-crate")
+        .with_stderr_contains("[DOCTEST] deep-crate")
+        .with_stdout_contains("test test_unit_root_cwd ... ok")
+        .with_stdout_contains("test test_unit_nested_cwd ... ok")
+        .with_stdout_contains("test test_unit_deep_cwd ... ok")
+        .with_stdout_contains("test test_integration_root_cwd ... ok")
+        .with_stdout_contains("test test_integration_nested_cwd ... ok")
+        .with_stdout_contains("test test_integration_deep_cwd ... ok")
+        .run();
+
+    p.cargo("test -p root-crate --all")
+        .with_stderr_contains("[DOCTEST] root-crate")
+        .with_stdout_contains("test test_unit_root_cwd ... ok")
+        .with_stdout_contains("test test_integration_root_cwd ... ok")
+        .run();
+
+    p.cargo("test -p nested-crate --all")
+        .with_stderr_contains("[DOCTEST] nested-crate")
+        .with_stdout_contains("test test_unit_nested_cwd ... ok")
+        .with_stdout_contains("test test_integration_nested_cwd ... ok")
+        .run();
+
+    p.cargo("test -p deep-crate --all")
+        .with_stderr_contains("[DOCTEST] deep-crate")
+        .with_stdout_contains("test test_unit_deep_cwd ... ok")
+        .with_stdout_contains("test test_integration_deep_cwd ... ok")
+        .run();
+
+    p.cargo("test --all")
+        .cwd("nested-crate")
+        .with_stderr_contains("[DOCTEST] nested-crate")
+        .with_stdout_contains("test test_unit_nested_cwd ... ok")
+        .with_stdout_contains("test test_integration_nested_cwd ... ok")
+        .run();
+
+    p.cargo("test --all")
+        .cwd("very/deeply/nested/deep-crate")
+        .with_stderr_contains("[DOCTEST] deep-crate")
+        .with_stdout_contains("test test_unit_deep_cwd ... ok")
+        .with_stdout_contains("test test_integration_deep_cwd ... ok")
+        .run();
+}