packages/flutter/test/animation/listener_helpers_test.dart

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  test('AnimationLocalStatusListenersMixin with AnimationLazyListenerMixin - removing unregistered listener is no-op', () {
    final _TestAnimationLocalStatusListeners uut = _TestAnimationLocalStatusListeners();
    void fakeListener(AnimationStatus status) { }
    uut.removeStatusListener(fakeListener);
    expect(uut.callsToStart, 0);
    expect(uut.callsToStop, 0);
  });

  test('AnimationLocalListenersMixin with AnimationLazyListenerMixin - removing unregistered listener is no-op', () {
    final _TestAnimationLocalListeners uut = _TestAnimationLocalListeners();
    void fakeListener() { }
    uut.removeListener(fakeListener);
    expect(uut.callsToStart, 0);
    expect(uut.callsToStop, 0);
  });
}

class _TestAnimationLocalStatusListeners with AnimationLocalStatusListenersMixin, AnimationLazyListenerMixin {
  int callsToStart = 0;
  int callsToStop = 0;

  @override
  void didStartListening() {
    callsToStart += 1;
  }

  @override
  void didStopListening() {
    callsToStop += 1;
  }
}

class _TestAnimationLocalListeners with AnimationLocalListenersMixin, AnimationLazyListenerMixin {
  int callsToStart = 0;
  int callsToStop = 0;

  @override
  void didStartListening() {
    callsToStart += 1;
  }

  @override
  void didStopListening() {
    callsToStop += 1;
  }
}