fix(doctor): detect missing trunk branch

The parent existence check was skipping trunk, so a deleted or
renamed trunk branch wouldn't be reported. Now checks
g.BranchExists(trunk) when the parent is trunk.

Author: cds-amal

cmd/doctor.go

@@ -120,7 +120,12 @@ func checkBranch(g *git.Git, cfg *config.Config, s *style.Style, branch string,
 	}
 
 	trunk, _ := cfg.GetTrunk() //nolint:errcheck // already validated in runDoctor
-	if parent != trunk && !g.BranchExists(parent) {
+	if parent == trunk {
+		if !g.BranchExists(trunk) {
+			result.issues = append(result.issues, s.Errorf("Trunk branch %s does not exist locally", trunk))
+			return result
+		}
+	} else if !g.BranchExists(parent) {
 		result.issues = append(result.issues, s.Errorf("Parent branch %s does not exist locally", parent))
 		return result
 	}

e2e/doctor_test.go

@@ -150,6 +150,22 @@ func TestDoctorFixUpdatesConfig(t *testing.T) {
 	}
 }
 
+func TestDoctorMissingTrunk(t *testing.T) {
+	env := NewTestEnv(t)
+
+	env.MustRun("init")
+	env.MustRun("create", "feature-a")
+	env.CreateCommit("work on a")
+
+	// Delete the trunk branch (main) while on feature-a
+	env.Git("branch", "-D", "main")
+
+	result := env.Run("doctor")
+	if !result.ContainsStdout("Trunk branch") || !result.ContainsStdout("does not exist locally") {
+		t.Errorf("expected missing trunk report, got: %s", result.Stdout)
+	}
+}
+
 func TestDoctorNotInitialized(t *testing.T) {
 	env := NewTestEnv(t)