packages/flutter_test/test/goldens_test.dart

// Copyright 2018 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:async';
import 'dart:io' as io;
import 'dart:typed_data';

import 'package:file/memory.dart';
import 'package:flutter_test/flutter_test.dart' hide test;
import 'package:flutter_test/flutter_test.dart' as test_package;

const List<int> _kExpectedBytes = <int>[1, 2, 3];

void main() {
  MemoryFileSystem fs;

  setUp(() {
    final FileSystemStyle style = io.Platform.isWindows
        ? FileSystemStyle.windows
        : FileSystemStyle.posix;
    fs = MemoryFileSystem(style: style);
  });

  /// Converts posix-style paths to the style associated with [fs].
  ///
  /// This allows us to deal in posix-style paths in the tests.
  String fix(String path) {
    if (path.startsWith('/')) {
      path = '${fs.style.drive}$path';
    }
    return path.replaceAll('/', fs.path.separator);
  }

  void test(String description, FutureOr<void> body()) {
    test_package.test(description, () {
      return io.IOOverrides.runZoned<FutureOr<void>>(
        body,
        createDirectory: (String path) => fs.directory(path),
        createFile: (String path) => fs.file(path),
        createLink: (String path) => fs.link(path),
        getCurrentDirectory: () => fs.currentDirectory,
        setCurrentDirectory: (String path) => fs.currentDirectory = path,
        getSystemTempDirectory: () => fs.systemTempDirectory,
        stat: (String path) => fs.stat(path),
        statSync: (String path) => fs.statSync(path),
        fseIdentical: (String p1, String p2) => fs.identical(p1, p2),
        fseIdenticalSync: (String p1, String p2) => fs.identicalSync(p1, p2),
        fseGetType: (String path, bool followLinks) => fs.type(path, followLinks: followLinks),
        fseGetTypeSync: (String path, bool followLinks) => fs.typeSync(path, followLinks: followLinks),
        fsWatch: (String a, int b, bool c) => throw UnsupportedError('unsupported'),
        fsWatchIsSupported: () => fs.isWatchSupported,
      );
    });
  }

  group('goldenFileComparator', () {
    test('is initialized by test framework', () {
      expect(goldenFileComparator, isNotNull);
      expect(goldenFileComparator, isInstanceOf<LocalFileComparator>());
      final LocalFileComparator comparator = goldenFileComparator;
      expect(comparator.basedir.path, contains('flutter_test'));
    });
  });

  group('LocalFileComparator', () {
    LocalFileComparator comparator;

    setUp(() {
      comparator = LocalFileComparator(fs.file(fix('/golden_test.dart')).uri, pathStyle: fs.path.style);
    });

    test('calculates basedir correctly', () {
      expect(comparator.basedir, fs.file(fix('/')).uri);
      comparator = LocalFileComparator(fs.file(fix('/foo/bar/golden_test.dart')).uri, pathStyle: fs.path.style);
      expect(comparator.basedir, fs.directory(fix('/foo/bar/')).uri);
    });

    test('can be instantiated with uri that represents file in same folder', () {
      comparator = LocalFileComparator(Uri.parse('foo_test.dart'), pathStyle: fs.path.style);
      expect(comparator.basedir, Uri.parse('./'));
    });

    group('compare', () {
      Future<bool> doComparison([ String golden = 'golden.png' ]) {
        final Uri uri = fs.file(fix(golden)).uri;
        return comparator.compare(
          Uint8List.fromList(_kExpectedBytes),
          uri,
        );
      }

      group('succeeds', () {
        test('when golden file is in same folder as test', () async {
          fs.file(fix('/golden.png')).writeAsBytesSync(_kExpectedBytes);
          final bool success = await doComparison();
          expect(success, isTrue);
        });

        test('when golden file is in subfolder of test', () async {
          fs.file(fix('/sub/foo.png'))
            ..createSync(recursive: true)
            ..writeAsBytesSync(_kExpectedBytes);
          final bool success = await doComparison('sub/foo.png');
          expect(success, isTrue);
        });

        group('when comparator instantiated with uri that represents file in same folder', () {
          test('and golden file is in same folder as test', () async {
            fs.file(fix('/foo/bar/golden.png'))
              ..createSync(recursive: true)
              ..writeAsBytesSync(_kExpectedBytes);
            fs.currentDirectory = fix('/foo/bar');
            comparator = LocalFileComparator(Uri.parse('local_test.dart'), pathStyle: fs.path.style);
            final bool success = await doComparison('golden.png');
            expect(success, isTrue);
          });

          test('and golden file is in subfolder of test', () async {
            fs.file(fix('/foo/bar/baz/golden.png'))
              ..createSync(recursive: true)
              ..writeAsBytesSync(_kExpectedBytes);
            fs.currentDirectory = fix('/foo/bar');
            comparator = LocalFileComparator(Uri.parse('local_test.dart'), pathStyle: fs.path.style);
            final bool success = await doComparison('baz/golden.png');
            expect(success, isTrue);
          });
        });
      });

      group('fails', () {
        test('when golden file does not exist', () async {
          final Future<bool> comparison = doComparison();
          expect(comparison, throwsA(isInstanceOf<TestFailure>()));
        });

        test('when golden bytes are leading subset of image bytes', () async {
          fs.file(fix('/golden.png')).writeAsBytesSync(<int>[1, 2]);
          expect(await doComparison(), isFalse);
        });

        test('when golden bytes are leading superset of image bytes', () async {
          fs.file(fix('/golden.png')).writeAsBytesSync(<int>[1, 2, 3, 4]);
          expect(await doComparison(), isFalse);
        });

        test('when golden bytes are trailing subset of image bytes', () async {
          fs.file(fix('/golden.png')).writeAsBytesSync(<int>[2, 3]);
          expect(await doComparison(), isFalse);
        });

        test('when golden bytes are trailing superset of image bytes', () async {
          fs.file(fix('/golden.png')).writeAsBytesSync(<int>[0, 1, 2, 3]);
          expect(await doComparison(), isFalse);
        });

        test('when golden bytes are disjoint from image bytes', () async {
          fs.file(fix('/golden.png')).writeAsBytesSync(<int>[4, 5, 6]);
          expect(await doComparison(), isFalse);
        });

        test('when golden bytes are empty', () async {
          fs.file(fix('/golden.png')).writeAsBytesSync(<int>[]);
          expect(await doComparison(), isFalse);
        });
      });
    });

    group('update', () {
      test('updates existing file', () async {
        fs.file(fix('/golden.png')).writeAsBytesSync(_kExpectedBytes);
        const List<int> newBytes = <int>[11, 12, 13];
        await comparator.update(fs.file('golden.png').uri, Uint8List.fromList(newBytes));
        expect(fs.file(fix('/golden.png')).readAsBytesSync(), newBytes);
      });

      test('creates non-existent file', () async {
        expect(fs.file(fix('/foo.png')).existsSync(), isFalse);
        const List<int> newBytes = <int>[11, 12, 13];
        await comparator.update(fs.file('foo.png').uri, Uint8List.fromList(newBytes));
        expect(fs.file(fix('/foo.png')).existsSync(), isTrue);
        expect(fs.file(fix('/foo.png')).readAsBytesSync(), newBytes);
      });
    });
  });
}