test(e2e): split the e2e suite into files so they run in parallel

test/e2e/actions_test.dart

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+@Tags(['e2e'])
+library;
+
+import 'package:shutter/src/run/manifest.dart';
+import 'package:test/test.dart';
+import 'package:yaml/yaml.dart';
+
+import '../helpers.dart';
+import 'e2e_helpers.dart';
+
+void main() {
+  test('actions change the shot; a target that matches none or two is an '
+      'error', () async {
+    final root = await exampleCopy();
+    Future<(String, Map<String, Shot>)> shoot(List<String> args) =>
+        shootIn(root, args);
+    writeFiles(root, {
+      'lib/preview/button_state_preview.dart': '''
+import 'package:flutter/material.dart';
+import 'package:flutter/widget_previews.dart';
+
+@Preview(name: 'State / button', size: Size(200, 80))
+Widget button() => Center(
+  child: ElevatedButton(onPressed: () {}, child: const Text('Save')),
+);
+
+@Preview(name: 'State / two buttons', size: Size(200, 80))
+Widget twoButtons() => Row(
+  children: [
+    TextButton(onPressed: () {}, child: const Text('Save')),
+    TextButton(onPressed: () {}, child: const Text('Save')),
+  ],
+);
+''',
+    });
+    const buttons = 'lib/preview/button_state_preview.dart';
+    final (plain, _) = await shoot([buttons]);
+    for (final action in [
+      ['--press', 'text:Save'],
+      ['--hover', 'type:ElevatedButton'],
+      ['--focus', 'type:ElevatedButton'],
+    ]) {
+      final (run, shots) = await shoot([buttons, ...action]);
+      final button = shots['State / button']!;
+      expect(button.status, ShotStatus.ok, reason: '$action ${button.error}');
+      expect(button.size, (200.0, 80.0));
+      final two = shots['State / two buttons']!;
+      expect(two.png, isNull);
+      expect(two.at, startsWith('lib/preview/button_state_preview.dart:'));
+      final diff = await shutter(root, ['diff', plain, run]);
+      final report = loadYaml(diff.stdout) as YamlMap;
+      expect(report['actions'], {
+        'before': <Object?>[],
+        'after': ['${action[0].substring(2)} ${action[1]}'],
+      });
+      final entry = (report['entries'] as YamlList).cast<YamlMap>().singleWhere(
+        (e) => e['name'] == 'State / button',
+      );
+      expect(entry['status'], 'changed', reason: '$action');
+    }
+    final (_, missed) = await shoot([buttons, '--tap', 'text:Cancel']);
+    expect(
+      missed['State / button']!.error,
+      'tap text:Cancel: no widget matches',
+    );
+    expect(
+      missed['State / two buttons']!.error,
+      'tap text:Cancel: no widget matches',
+    );
+    final (_, twice) = await shoot([buttons, '--press', 'text:Save']);
+    expect(
+      twice['State / two buttons']!.error,
+      'press text:Save: 2 widgets match; name one',
+    );
+  });
+}

test/e2e/capture_test.dart

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+@Tags(['e2e'])
+library;
+
+import 'dart:io';
+
+import 'package:image/image.dart' as img;
+import 'package:path/path.dart' as p;
+import 'package:shutter/src/run/manifest.dart';
+import 'package:test/test.dart';
+
+import '../helpers.dart';
+import 'e2e_helpers.dart';
+
+/// A dropdown whose menu opens below its 60-high preview.
+const menuPreview = '''
+import 'package:flutter/material.dart';
+import 'package:flutter/widget_previews.dart';
+
+@Preview(name: 'State / menu', size: Size(200, 60))
+Widget menu() => Align(
+  alignment: Alignment.topLeft,
+  child: DropdownButton<String>(
+    value: 'a',
+    items: const [
+      DropdownMenuItem(value: 'a', child: Text('Alpha')),
+      DropdownMenuItem(value: 'b', child: Text('Beta')),
+    ],
+    onChanged: (_) {},
+  ),
+);
+''';
+
+void main() {
+  test('--capture screen holds the viewport and what opens above the '
+      'preview', () async {
+    final root = await exampleCopy();
+    Future<(String, Map<String, Shot>)> shoot(List<String> args) =>
+        shootIn(root, args);
+    writeFiles(root, {
+      'lib/preview/menu_state_preview.dart': menuPreview,
+      'lib/preview/route_preview.dart': routePreview,
+      'lib/preview/box_preview.dart': '''
+import 'package:flutter/widget_previews.dart';
+import 'package:flutter/widgets.dart';
+
+@Preview(name: 'Box', size: Size(100, 50))
+Widget box() => const ColoredBox(color: Color(0xFF0000FF));
+''',
+    });
+    // The screen is drawn at the same scale as the preview: a 100x50 box
+    // at the top left of a 200x100 viewport fills a quarter of the image.
+    final (boxRun, boxShots) = await shoot([
+      'lib/preview/box_preview.dart',
+      '--capture',
+      'screen',
+      '--viewport',
+      '200x100',
+    ]);
+    final boxImage = img.decodePng(
+      File(p.join(boxRun, boxShots['Box']!.png!)).readAsBytesSync(),
+    )!;
+    expect((boxImage.width, boxImage.height), (400, 200));
+    bool blue(int x, int y) {
+      final pixel = boxImage.getPixel(x, y);
+      return (pixel.r, pixel.g, pixel.b) == (0, 0, 255);
+    }
+
+    expect(blue(199, 99), isTrue);
+    expect(blue(201, 50), isFalse);
+    expect(blue(50, 101), isFalse);
+
+    // The menu's second item lies below the 60-high preview, in the
+    // screen only.
+    const menu = 'lib/preview/menu_state_preview.dart';
+    final screen = ['--capture', 'screen', '--viewport', '200x240'];
+    final (closed, closedShots) = await shoot([menu, ...screen]);
+    expect(closedShots['State / menu']!.size, (200.0, 240.0));
+    final (open, openShots) = await shoot([
+      menu,
+      ...screen,
+      '--tap',
+      'type:DropdownButton<String>',
+    ]);
+    final opened = openShots['State / menu']!;
+    expect(opened.status, ShotStatus.ok, reason: opened.error);
+    final image = img.decodePng(
+      File(p.join(open, opened.png!)).readAsBytesSync(),
+    )!;
+    expect((image.width, image.height), (400, 480));
+    final closedImage = img.decodePng(
+      File(p.join(closed, closedShots['State / menu']!.png!)).readAsBytesSync(),
+    )!;
+    var differing = 0;
+    for (var y = 120; y < 480; y++) {
+      for (var x = 0; x < 400; x++) {
+        final (a, b) = (image.getPixel(x, y), closedImage.getPixel(x, y));
+        if ((a.r, a.g, a.b, a.a) != (b.r, b.g, b.b, b.a)) differing++;
+      }
+    }
+    expect(differing, greaterThan(0));
+
+    // A page a tap pushes is in the screen; its transition takes 450 ms,
+    // still under way at the default 300, over by 700.
+    const route = ['lib/preview/route_preview.dart', '--tap', 'text:Go'];
+    Future<String> settled(String ms) async =>
+        (await shoot([...route, '--capture', 'screen', '--settle', ms])).$1;
+    final at300 = await settled('300');
+    final pushed = RunManifest.read(at300).shots.single;
+    expect(pushed.status, ShotStatus.ok, reason: pushed.error);
+    expect(pushed.size, (200.0, 100.0));
+    final (at700, at800) = (await settled('700'), await settled('800'));
+    expect((await shutter(root, ['diff', at300, at700])).exitCode, 1);
+    expect((await shutter(root, ['diff', at700, at800])).exitCode, 0);
+  });
+}

test/e2e/e2e_helpers.dart

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+import 'dart:io';
+
+import 'package:path/path.dart' as p;
+import 'package:shutter/src/cli/context.dart';
+import 'package:shutter/src/project/flutter_sdk.dart';
+import 'package:shutter/src/run/manifest.dart';
+import 'package:test/test.dart';
+import 'package:yaml/yaml.dart';
+
+import '../helpers.dart';
+
+/// Copies `example/` (sources only) into a temporary project and
+/// resolves its dependencies.
+Future<String> exampleCopy() async {
+  final root = tempDir();
+  for (final entity in Directory('example').listSync(recursive: true)) {
+    final rel = p.relative(entity.path, from: 'example');
+    if (entity is! File ||
+        rel.startsWith('.dart_tool') ||
+        rel.startsWith('build')) {
+      continue;
+    }
+    File(p.join(root, rel))
+      ..createSync(recursive: true)
+      ..writeAsBytesSync(entity.readAsBytesSync());
+  }
+  final pubGet = await Process.run(flutter, [
+    'pub',
+    'get',
+  ], workingDirectory: root);
+  expect(pubGet.exitCode, 0, reason: '${pubGet.stdout}${pubGet.stderr}');
+  return root;
+}
+
+final String flutter = FlutterSdk.require(environment: Platform.environment)
+    .executable();
+
+Future<CliResult> shutter(String root, List<String> args) =>
+    runCli(args, ShutterContext(workingDirectory: root));
+
+String lastRun(String root) => (Directory(
+  p.join(root, '.dart_tool', 'shutter', 'runs'),
+).listSync().map((d) => d.path).toList()..sort()).last;
+
+/// Shoots [args] in [root]: the run directory and its shots by name.
+Future<(String, Map<String, Shot>)> shootIn(
+  String root,
+  List<String> args,
+) async {
+  final result = await shutter(root, ['shot', ...args]);
+  final run = (loadYaml(result.stdout) as YamlMap)['run'] as String;
+  return (run, {for (final s in RunManifest.read(run).shots) s.name: s});
+}
+
+/// A button that pushes a page.
+const routePreview = '''
+import 'package:flutter/material.dart';
+import 'package:flutter/widget_previews.dart';
+
+@Preview(name: 'Route', size: Size(200, 100))
+Widget route() => Builder(
+  builder: (context) => ElevatedButton(
+    onPressed: () => Navigator.of(context).push(
+      MaterialPageRoute<void>(
+        builder: (_) => const Scaffold(body: Text('Next page')),
+      ),
+    ),
+    child: const Text('Go'),
+  ),
+);
+''';