From 3d62071f77d8ecc6deb8316f857516b8b0324da5 Mon Sep 17 00:00:00 2001
From: Alex Dunmow <alex.dunmow@millcrest.com.au>
Date: Wed, 3 Jun 2026 10:13:53 +0800
Subject: [PATCH] test(cli): cover autoCommitPluginMod detached HEAD and
 missing git

Adds coverage for two git-edge cases: commits land correctly on a
detached HEAD with the prior commit as parent, and an empty PATH
produces a git-mentioning error rather than a panic.
---
 cmd/ninja/cmd/plugin_test.go | 70 ++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/cmd/ninja/cmd/plugin_test.go b/cmd/ninja/cmd/plugin_test.go
index b84113e..1ca84c8 100644
--- a/cmd/ninja/cmd/plugin_test.go
+++ b/cmd/ninja/cmd/plugin_test.go
@@ -87,6 +87,76 @@ func TestAutoCommitPluginMod_NoopWhenClean(t *testing.T) {
 	}
 }
 
+func TestAutoCommitPluginMod_WorksOnDetachedHEAD(t *testing.T) {
+	dir := t.TempDir()
+	runGit(t, dir, "init", "-q")
+	if err := os.WriteFile(filepath.Join(dir, "README.md"), []byte("hi"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	runGit(t, dir, "add", "README.md")
+	runGit(t, dir, "commit", "-qm", "init")
+
+	initialSHA := gitHeadSHA(t, dir)
+	runGit(t, dir, "checkout", "-q", initialSHA)
+
+	if err := os.WriteFile(filepath.Join(dir, "plugin.mod"),
+		[]byte("[plugin]\nname = \"x\"\nscope = \"@s\"\nversion = \"0.1.0\"\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	t.Chdir(dir)
+	if err := autoCommitPluginMod(); err != nil {
+		t.Fatalf("autoCommitPluginMod on detached HEAD: %v", err)
+	}
+
+	afterSHA := gitHeadSHA(t, dir)
+	if afterSHA == initialSHA {
+		t.Fatalf("expected new commit on detached HEAD, HEAD still at %s", afterSHA)
+	}
+
+	subject := gitLogSubject(t, dir)
+	if subject != "Add plugin.mod" {
+		t.Errorf("expected latest commit subject 'Add plugin.mod', got %q", subject)
+	}
+
+	parentCmd := exec.Command("git", "rev-parse", "HEAD^")
+	parentCmd.Dir = dir
+	parentOut, err := parentCmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("git rev-parse HEAD^: %v\n%s", err, parentOut)
+	}
+	parentSHA := strings.TrimSpace(string(parentOut))
+	if parentSHA != initialSHA {
+		t.Errorf("expected new commit parent to be %s, got %s", initialSHA, parentSHA)
+	}
+}
+
+func TestAutoCommitPluginMod_ErrorsWhenGitMissing(t *testing.T) {
+	dir := t.TempDir()
+	runGit(t, dir, "init", "-q")
+	if err := os.WriteFile(filepath.Join(dir, "README.md"), []byte("hi"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	runGit(t, dir, "add", "README.md")
+	runGit(t, dir, "commit", "-qm", "init")
+
+	if err := os.WriteFile(filepath.Join(dir, "plugin.mod"),
+		[]byte("[plugin]\nname = \"x\"\nscope = \"@s\"\nversion = \"0.1.0\"\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	t.Chdir(dir)
+	t.Setenv("PATH", "")
+
+	err := autoCommitPluginMod()
+	if err == nil {
+		t.Fatal("expected error when git is missing from PATH, got nil")
+	}
+	if !strings.Contains(err.Error(), "git") {
+		t.Errorf("error %q should mention 'git'", err.Error())
+	}
+}
+
 func gitLogSubject(t *testing.T, dir string) string {
 	t.Helper()
 	cmd := exec.Command("git", "log", "-1", "--pretty=%s")