Added build_dir tests

tests/testsuite/build_dir.rs

@@ -0,0 +1,110 @@
+//! Tests for `build.build-dir` config property.
+
+use std::path::PathBuf;
+
+use cargo_test_support::prelude::*;
+use cargo_test_support::project;
+
+#[cargo_test]
+fn binary_with_debug() {
+    let p = project()
+        .file("src/main.rs", r#"fn main() { println!("Hello, World!") }"#)
+        .file(
+            ".cargo/config.toml",
+            r#"
+            [build]
+            build-dir = "build"
+            "#,
+        )
+        .build();
+
+    p.cargo("build -Z unstable-options -Z build-dir")
+        .masquerade_as_nightly_cargo(&["build-dir"])
+        .enable_mac_dsym()
+        .run();
+
+    assert_build_dir(p.root().join("build"), "debug", true);
+    assert_build_dir(p.root().join("target"), "debug", false);
+
+    // Verify the binary was copied to the `target` dir
+    assert!(p.root().join("target/debug/foo").is_file());
+}
+
+#[cargo_test]
+fn binary_with_release() {
+    let p = project()
+        .file("src/main.rs", r#"fn main() { println!("Hello, World!") }"#)
+        .file(
+            ".cargo/config.toml",
+            r#"
+            [build]
+            build-dir = "build"
+            "#,
+        )
+        .build();
+
+    p.cargo("build -Z unstable-options -Z build-dir --release")
+        .masquerade_as_nightly_cargo(&["build-dir"])
+        .enable_mac_dsym()
+        .run();
+
+    assert_build_dir(p.root().join("build"), "release", true);
+    assert_build_dir(p.root().join("target"), "release", false);
+
+    // Verify the binary was copied to the `target` dir
+    assert!(p.root().join("target/release/foo").is_file());
+}
+
+#[cargo_test]
+fn should_default_to_target() {
+    let p = project()
+        .file("src/main.rs", r#"fn main() { println!("Hello, World!") }"#)
+        .build();
+
+    p.cargo("build -Z unstable-options -Z build-dir")
+        .masquerade_as_nightly_cargo(&["build-dir"])
+        .enable_mac_dsym()
+        .run();
+
+    assert_build_dir(p.root().join("target"), "debug", true);
+    // Verify the binary exists in the correct location
+    assert!(p.root().join("target/debug/foo").is_file());
+}
+
+#[track_caller]
+fn assert_build_dir(path: PathBuf, profile: &str, is_build_dir: bool) {
+    println!("checking if {path:?} is a build directory ({is_build_dir})");
+    // For things that are in both `target` and the build directory we only check if they are
+    // present if `is_build_dir` is true.
+    if is_build_dir {
+        assert!(path.join("CACHEDIR.TAG").is_file());
+        assert_eq!(is_build_dir, path.join(profile).is_dir());
+    }
+
+    let error_message = |dir: &str| {
+        if is_build_dir {
+            format!("`{dir}` dir was expected but not found")
+        } else {
+            format!("`{dir}` dir was not expected but was found")
+        }
+    };
+
+    assert_eq!(
+        is_build_dir,
+        path.join(profile).join("deps").is_dir(),
+        "{}",
+        error_message("deps")
+    );
+    assert_eq!(
+        is_build_dir,
+        path.join(profile).join("build").is_dir(),
+        "{}",
+        error_message("build")
+    );
+    assert_eq!(
+        is_build_dir,
+        path.join(profile).join("incremental").is_dir(),
+        "{}",
+        error_message("incremental")
+    );
+}

tests/testsuite/main.rs

@@ -11,6 +11,7 @@ mod bad_manifest_path;
 mod bench;
 mod binary_name;
 mod build;
+mod build_dir;
 mod build_plan;
 mod build_script;
 mod build_script_env;