packages/flutter/test/widgets/shader_mask_test.dart

// Copyright 2015 The Chromium 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 'dart:ui' show Shader;

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

Shader createShader(Rect bounds) {
  return const LinearGradient(
    begin: Alignment.topCenter,
    end: Alignment.bottomCenter,
    colors: <Color>[Color(0x00FFFFFF), Color(0xFFFFFFFF)],
    stops: <double>[0.1, 0.35],
  ).createShader(bounds);
}


void main() {
  testWidgets('Can be constructed', (WidgetTester tester) async {
    final Widget child = Container(width: 100.0, height: 100.0);
    await tester.pumpWidget(ShaderMask(child: child, shaderCallback: createShader));
  });

  testWidgets('Bounds rect includes offset', (WidgetTester tester) async {
    Rect shaderBounds;
    Shader recordShaderBounds(Rect bounds) {
      shaderBounds = bounds;
      return createShader(bounds);
    }

    final Widget widget = Align(
      alignment: Alignment.center,
      child: SizedBox(
        width: 400.0,
        height: 400.0,
        child: ShaderMask(
          shaderCallback: recordShaderBounds,
          child: Container(width: 100.0, height: 100.0),
        ),
      ),
    );
    await tester.pumpWidget(widget);

    // The shader bounds rectangle should reflect the position of the centered SizedBox.
    expect(shaderBounds, equals(Rect.fromLTWH(200.0, 100.0, 400.0, 400.0)));
  });
}