1 files changed, 121 insertions, 0 deletions
diff --git a/helix-vcs/src/git/test.rs b/helix-vcs/src/git/test.rs
new file mode 100644
index 00000000..d6e9af08
--- /dev/null
+++ b/helix-vcs/src/git/test.rs
@@ -0,0 +1,121 @@
+use std::{fs::File, io::Write, path::Path, process::Command};
+
+use tempfile::TempDir;
+
+use crate::{DiffProvider, Git};
+
+fn exec_git_cmd(args: &str, git_dir: &Path) {
+    let res = Command::new("git")
+        .arg("-C")
+        .arg(git_dir) // execute the git command in this directory
+        .args(args.split_whitespace())
+        .env_remove("GIT_DIR")
+        .env_remove("GIT_ASKPASS")
+        .env_remove("SSH_ASKPASS")
+        .env("GIT_TERMINAL_PROMPT", "false")
+        .env("GIT_AUTHOR_DATE", "2000-01-01 00:00:00 +0000")
+        .env("GIT_AUTHOR_EMAIL", "author@example.com")
+        .env("GIT_AUTHOR_NAME", "author")
+        .env("GIT_COMMITTER_DATE", "2000-01-02 00:00:00 +0000")
+        .env("GIT_COMMITTER_EMAIL", "committer@example.com")
+        .env("GIT_COMMITTER_NAME", "committer")
+        .env("GIT_CONFIG_COUNT", "2")
+        .env("GIT_CONFIG_KEY_0", "commit.gpgsign")
+        .env("GIT_CONFIG_VALUE_0", "false")
+        .env("GIT_CONFIG_KEY_1", "init.defaultBranch")
+        .env("GIT_CONFIG_VALUE_1", "main")
+        .output()
+        .unwrap_or_else(|_| panic!("`git {args}` failed"));
+    if !res.status.success() {
+        println!("{}", String::from_utf8_lossy(&res.stdout));
+        eprintln!("{}", String::from_utf8_lossy(&res.stderr));
+        panic!("`git {args}` failed (see output above)")
+    }
+}
+
+fn create_commit(repo: &Path, add_modified: bool) {
+    if add_modified {
+        exec_git_cmd("add -A", repo);
+    }
+    exec_git_cmd("commit -m message", repo);
+}
+
+fn empty_git_repo() -> TempDir {
+    let tmp = tempfile::tempdir().expect("create temp dir for git testing");
+    exec_git_cmd("init", tmp.path());
+    exec_git_cmd("config user.email test@helix.org", tmp.path());
+    exec_git_cmd("config user.name helix-test", tmp.path());
+    tmp
+}
+
+#[test]
+fn missing_file() {
+    let temp_git = empty_git_repo();
+    let file = temp_git.path().join("file.txt");
+    File::create(&file).unwrap().write_all(b"foo").unwrap();
+
+    assert_eq!(Git.get_diff_base(&file), None);
+}
+
+#[test]
+fn unmodified_file() {
+    let temp_git = empty_git_repo();
+    let file = temp_git.path().join("file.txt");
+    let contents = b"foo".as_slice();
+    File::create(&file).unwrap().write_all(contents).unwrap();
+    create_commit(temp_git.path(), true);
+    assert_eq!(Git.get_diff_base(&file), Some(Vec::from(contents)));
+}
+
+#[test]
+fn modified_file() {
+    let temp_git = empty_git_repo();
+    let file = temp_git.path().join("file.txt");
+    let contents = b"foo".as_slice();
+    File::create(&file).unwrap().write_all(contents).unwrap();
+    create_commit(temp_git.path(), true);
+    File::create(&file).unwrap().write_all(b"bar").unwrap();
+
+    assert_eq!(Git.get_diff_base(&file), Some(Vec::from(contents)));
+}
+
+/// Test that `get_file_head` does not return content for a directory.
+/// This is important to correctly cover cases where a directory is removed and replaced by a file.
+/// If the contents of the directory object were returned a diff between a path and the directory children would be produced.
+#[test]
+fn directory() {
+    let temp_git = empty_git_repo();
+    let dir = temp_git.path().join("file.txt");
+    std::fs::create_dir(&dir).expect("");
+    let file = dir.join("file.txt");
+    let contents = b"foo".as_slice();
+    File::create(&file).unwrap().write_all(contents).unwrap();
+
+    create_commit(temp_git.path(), true);
+
+    std::fs::remove_dir_all(&dir).unwrap();
+    File::create(&dir).unwrap().write_all(b"bar").unwrap();
+    assert_eq!(Git.get_diff_base(&dir), None);
+}
+
+/// Test that `get_file_head` does not return content for a symlink.
+/// This is important to correctly cover cases where a symlink is removed and replaced by a file.
+/// If the contents of the symlink object were returned a diff between a path and the actual file would be produced (bad ui).
+#[cfg(any(unix, windows))]
+#[test]
+fn symlink() {
+    #[cfg(unix)]
+    use std::os::unix::fs::symlink;
+    #[cfg(not(unix))]
+    use std::os::windows::fs::symlink_file as symlink;
+    let temp_git = empty_git_repo();
+    let file = temp_git.path().join("file.txt");
+    let contents = b"foo".as_slice();
+    File::create(&file).unwrap().write_all(contents).unwrap();
+    let file_link = temp_git.path().join("file_link.txt");
+    symlink("file.txt", &file_link).unwrap();
+
+    create_commit(temp_git.path(), true);
+    assert_eq!(Git.get_diff_base(&file_link), None);
+    assert_eq!(Git.get_diff_base(&file), Some(Vec::from(contents)));
+}