fix: address code review — error-path tests, edge cases, UX improvements

internal/workspace/workspace_service_test.go

@@ -250,6 +250,22 @@ func (t *trackGit) Checkout(_ context.Context, _, branch string) error {
 	return nil
 }
 
+type errFetchGit struct {
+	git.Runner
+	err error
+}
+
+func (e *errFetchGit) FetchRemoteBranch(_ context.Context, _, _ string, _ *git.Credential) error {
+	return e.err
+}
+
+type errCheckoutGit struct {
+	git.Runner
+	err error
+}
+
+func (e *errCheckoutGit) Checkout(_ context.Context, _, _ string) error { return e.err }
+
 type noopAudit struct{}
 
 func (noopAudit) Record(_ context.Context, _ audit.Entry) error { return nil }
@@ -404,11 +420,9 @@ func TestCloneRunner_Failure(t *testing.T) {
 }
 
 func TestWorkspaceService_Update_DefaultBranch_Switch(t *testing.T) {
-	// 切换 default_branch 时，service 必须先 fetch+checkout 远端分支，再落库。
-	// 注意：fakeGit 默认 stub 不会记录调用，本测试仅断言最终 DB 状态。
 	t.Parallel()
 	pa := &fakePA{pid: uuid.New(), canRead: true, canWrite: true}
-	fg := &fakeGit{}
+	fg := &trackGit{Runner: &fakeGit{}}
 	svc, repo := newSvc(t, pa, nil, fg)
 	caller := Caller{UserID: uuid.New()}
 
@@ -426,6 +440,52 @@ func TestWorkspaceService_Update_DefaultBranch_Switch(t *testing.T) {
 	})
 	require.NoError(t, err)
 	require.Equal(t, "develop", repo.wss[wsID].DefaultBranch)
+	require.Equal(t, []string{"develop"}, fg.fetchRemoteBranchCalls)
+	require.Equal(t, []string{"develop"}, fg.checkoutCalls)
+}
+
+func TestWorkspaceService_Update_DefaultBranch_FetchFails(t *testing.T) {
+	t.Parallel()
+	pa := &fakePA{pid: uuid.New(), canRead: true, canWrite: true}
+	fg := &errFetchGit{Runner: &fakeGit{}, err: errors.New("remote branch not found")}
+	svc, repo := newSvc(t, pa, nil, fg)
+	caller := Caller{UserID: uuid.New()}
+
+	wsID := uuid.New()
+	repo.wss[wsID] = &Workspace{
+		ID: wsID, ProjectID: pa.pid, Slug: "ws1", Name: "W1",
+		DefaultBranch: "main", MainPath: "/data/ws1/main",
+	}
+
+	newBr := "nonexistent"
+	_, err := svc.Update(context.Background(), caller, wsID, UpdateWorkspaceInput{
+		DefaultBranch: &newBr,
+	})
+	require.Error(t, err)
+	// DB should NOT be updated
+	require.Equal(t, "main", repo.wss[wsID].DefaultBranch)
+}
+
+func TestWorkspaceService_Update_DefaultBranch_CheckoutFails(t *testing.T) {
+	t.Parallel()
+	pa := &fakePA{pid: uuid.New(), canRead: true, canWrite: true}
+	fg := &errCheckoutGit{Runner: &fakeGit{}, err: errors.New("dirty working tree")}
+	svc, repo := newSvc(t, pa, nil, fg)
+	caller := Caller{UserID: uuid.New()}
+
+	wsID := uuid.New()
+	repo.wss[wsID] = &Workspace{
+		ID: wsID, ProjectID: pa.pid, Slug: "ws1", Name: "W1",
+		DefaultBranch: "main", MainPath: "/data/ws1/main",
+	}
+
+	newBr := "develop"
+	_, err := svc.Update(context.Background(), caller, wsID, UpdateWorkspaceInput{
+		DefaultBranch: &newBr,
+	})
+	require.Error(t, err)
+	// DB should NOT be updated
+	require.Equal(t, "main", repo.wss[wsID].DefaultBranch)
 }
 
 func TestWorkspaceService_Update_DefaultBranch_SameValue_NoGitOps(t *testing.T) {
@@ -460,7 +520,7 @@ func TestWorkspaceService_ListBranches(t *testing.T) {
 	wsID := uuid.New()
 	repo.wss[wsID] = &Workspace{
 		ID: wsID, ProjectID: pa.pid, Slug: "ws1",
-		DefaultBranch: "main", MainPath: "/data/ws1/main",
+		DefaultBranch: "main", MainPath: t.TempDir(),
 	}
 
 	branches, err := svc.ListBranches(context.Background(), caller, wsID)