Repository: tokio-rs/tokio
File: tokio/tests/fs_link.rs (Rust)

Code before:
#[tokio::test]
#[cfg_attr(miri, ignore)] // No `linkat` in miri.
async fn test_hard_link_error_source_not_found() {
    let dir = tempdir().unwrap();
    let src = dir.path().join("nonexistent.txt");
    let dst = dir.path().join("dst.txt");

    let result = fs::hard_link(&src, &dst).await;

    assert!(result.is_err());
    let err = result.unwrap_err();
    assert_eq!(err.kind(), std::io::ErrorKind::NotFound);
}

#[tokio::test]
#[cfg_attr(miri, ignore)] // No `linkat` in miri.
async fn test_hard_link_error_destination_already_exists() {
    let dir = tempdir().unwrap();
    let src = dir.path().join("src.txt");
    let dst = dir.path().join("dst.txt");

    // Create source file
    std::fs::File::create(&src)
        .unwrap()
        .write_all(b"source content")
        .unwrap();

    // Create destination file
    std::fs::File::create(&dst)
        .unwrap()
        .write_all(b"destination content")
        .unwrap();

    // Attempt to create hard link when destination already exists
    let result = fs::hard_link(&src, &dst).await;

    assert!(result.is_err());
    let err = result.unwrap_err();
    assert_eq!(err.kind(), std::io::ErrorKind::AlreadyExists);
}

#[tokio::test]
#[cfg_attr(miri, ignore)] // No `linkat` in miri.
async fn test_hard_link_error_source_is_directory() {
    let dir = tempdir().unwrap();
    let src_dir = dir.path().join("src_directory");
    let dst = dir.path().join("dst.txt");

    // Create source directory
    fs::create_dir(&src_dir).await.unwrap();


Review comment (suggestion):
```suggestion
    std::fs::write(src, b"source content").unwrap();
```

Code after:
#[tokio::test]
#[cfg_attr(miri, ignore)] // No `linkat` in miri.
async fn test_hard_link_error_source_not_found() {
    let dir = tempdir().unwrap();
    let src = dir.path().join("nonexistent.txt");
    let dst = dir.path().join("dst.txt");

    let err = fs::hard_link(&src, &dst).await.unwrap_err();
    assert_eq!(err.kind(), std::io::ErrorKind::NotFound);
}

#[tokio::test]
#[cfg_attr(miri, ignore)] // No `linkat` in miri.
async fn test_hard_link_error_destination_already_exists() {
    let dir = tempdir().unwrap();
    let src = dir.path().join("src.txt");
    let dst = dir.path().join("dst.txt");

    // Create source file
    std::fs::write(&src, b"source content").unwrap();

    // Create destination file
    std::fs::write(&dst, b"destination content").unwrap();

    // Attempt to create hard link when destination already exists
    let err = fs::hard_link(&src, &dst).await.unwrap_err();
    assert_eq!(err.kind(), std::io::ErrorKind::AlreadyExists);
}

#[tokio::test]
#[cfg_attr(miri, ignore)] // No `linkat` in miri.
async fn test_hard_link_error_source_is_directory() {
    let dir = tempdir().unwrap();
    let src_dir = dir.path().join("src_directory");
    let dst = dir.path().join("dst.txt");

    // Create source directory
    fs::create_dir(&src_dir).await.unwrap();

    // Attempt to create hard link from a directory
    // On most systems, hard linking directories is not allowed
    let err = fs::hard_link(&src_dir, &dst).await.unwrap_err();

    // Different platforms return different error kinds
    #[cfg(unix)]
    assert!(
        err.kind() == std::io::ErrorKind::PermissionDenied
            || err.kind() == std::io::ErrorKind::Other
    );

    #[cfg(windows)]