feat: storage sync/async funcs

pkg/storage/fs/fs.go

@@ -102,7 +102,7 @@ func NewFS(storageRoot string) (*fsStorage, error) {
 
 func (s *fsStorage) StateExistsAsync(callback func(bool, error)) {
 	go func() {
-		exists, err := s.FileExists(stateFileName)
+		exists, err := s.StateExists()
 		if callback != nil {
 			callback(exists, err)
 		}
@@ -111,7 +111,7 @@ func (s *fsStorage) StateExistsAsync(callback func(bool, error)) {
 
 func (s *fsStorage) LoadStateAsync(callback func(client.State, error)) {
 	go func() {
-		state, err := s.loadStateSync()
+		state, err := s.LoadState()
 		if callback != nil {
 			callback(state, err)
 		}
@@ -120,7 +120,7 @@ func (s *fsStorage) LoadStateAsync(callback func(client.State, error)) {
 
 func (s *fsStorage) SaveStateAsync(state client.State, callback func(error)) {
 	go func() {
-		err := s.saveStateSync(state)
+		err := s.SaveState(state)
 		if callback != nil {
 			callback(err)
 		}
@@ -253,7 +253,11 @@ func (s *fsStorage) ListFiles() ([]string, error) {
 	return files, nil
 }
 
-func (s *fsStorage) loadStateSync() (client.State, error) {
+func (s *fsStorage) StateExists() (bool, error) {
+	return s.FileExists(stateFileName)
+}
+
+func (s *fsStorage) LoadState() (client.State, error) {
 	data, err := s.ReadFile(stateFileName)
 	if err != nil {
 		return client.State{}, err
@@ -261,7 +265,7 @@ func (s *fsStorage) loadStateSync() (client.State, error) {
 	return unmarshalState(data)
 }
 
-func (s *fsStorage) saveStateSync(state client.State) error {
+func (s *fsStorage) SaveState(state client.State) error {
 	data, err := marshalState(state)
 	if err != nil {
 		return err

pkg/storage/fs/fs_test.go

@@ -22,6 +22,39 @@ type callbackResult[T any] struct {
 	err   error
 }
 
+func TestStateRoundTrip(t *testing.T) {
+	s := newTestStorage(t)
+	want := sampleState()
+
+	exists, err := s.StateExists()
+	if err != nil {
+		t.Fatalf("state exists before save: %v", err)
+	}
+	if exists {
+		t.Fatal("state file should not exist before save")
+	}
+
+	if err := s.SaveState(want); err != nil {
+		t.Fatalf("save state: %v", err)
+	}
+
+	exists, err = s.StateExists()
+	if err != nil {
+		t.Fatalf("state exists after save: %v", err)
+	}
+	if !exists {
+		t.Fatal("state file should exist after save")
+	}
+
+	got, err := s.LoadState()
+	if err != nil {
+		t.Fatalf("load state: %v", err)
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("loaded state mismatch\nwant: %#v\ngot:  %#v", want, got)
+	}
+}
+
 func TestStateRoundTripAsync(t *testing.T) {
 	s := newTestStorage(t)
 	want := sampleState()

pkg/storage/storage.go

@@ -14,7 +14,9 @@ type Storage interface {
 	DeleteFile(string) error
 	ListFiles() ([]string, error)
 
-	// StateExistss() (bool, error)
+	StateExists() (bool, error)
+	LoadState() (client.State, error)
+	SaveState(client.State) error
 }
 
 // UIStorage manages Client's data local storing and retrieval.