Implement controlled app launch (T-401)

core/installer/switcher_test.go

@@ -57,6 +57,41 @@ func TestSwitcherRemovesFailedInitialInstall(t *testing.T) {
 	assertMissing(t, filepath.Join(root, transactionFileName))
 }
 
+func TestSwitcherPreSwitchCheckPreventsUpdateAndCleansStaging(t *testing.T) {
+	root := makeInstallRoot(t, "old", "new")
+	checkErr := errors.New("target is running")
+	switcher := NewSwitcherWithPreSwitchCheck(
+		func(string) error { return nil },
+		func() error {
+			assertVersion(t, filepath.Join(root, "current"), "old")
+			assertVersion(t, filepath.Join(root, "staging"), "new")
+			return checkErr
+		},
+	)
+
+	err := switcher.Switch(root)
+	if !errors.Is(err, checkErr) {
+		t.Fatalf("Switch() error = %v, want %v", err, checkErr)
+	}
+	assertVersion(t, filepath.Join(root, "current"), "old")
+	assertMissing(t, filepath.Join(root, "staging"))
+	assertMissing(t, filepath.Join(root, "backup"))
+	assertMissing(t, filepath.Join(root, transactionFileName))
+}
+
+func TestSwitcherSkipsPreSwitchCheckForInitialInstall(t *testing.T) {
+	root := makeInstallRoot(t, "", "new")
+	switcher := NewSwitcherWithPreSwitchCheck(
+		func(string) error { return nil },
+		func() error { return errors.New("must not run") },
+	)
+
+	if err := switcher.Switch(root); err != nil {
+		t.Fatalf("Switch() error = %v", err)
+	}
+	assertVersion(t, filepath.Join(root, "current"), "new")
+}
+
 func TestRecoverInterruptedSwitch(t *testing.T) {
 	tests := []struct {
 		name        string