fix macos empty metadata test

Author: pvdrz

tests/run-pass/fs.rs

@@ -18,7 +18,9 @@ fn test_metadata(bytes: &[u8], path: &Path) -> Result<()> {
 
 // FIXME: Implement stat64 for macos.
 #[cfg(not(target_os = "linux"))]
-fn test_metadata(_bytes: &[u8], _path: &Path) {}
+fn test_metadata(_bytes: &[u8], _path: &Path) -> Result<()> {
+    Ok(())
+}
 
 fn main() {
     let tmp = std::env::temp_dir();
@@ -56,5 +58,7 @@ fn main() {
     // Removing a non-existing file should fail with a "not found" error.
     assert_eq!(ErrorKind::NotFound, remove_file(&path).unwrap_err().kind());
     // Reading the metadata of a non-existing file should fail with a "not found" error.
-    assert_eq!(ErrorKind::NotFound, test_metadata(bytes, &path).unwrap_err().kind());
+    if cfg!(target_os = "linux") {
+        assert_eq!(ErrorKind::NotFound, test_metadata(bytes, &path).unwrap_err().kind());
+    }
 }