lib/web_ui/dev/test_runner.dart - external/github.com/flutter/engine - Git at Google

 // Copyright 2013 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.

 // @dart = 2.6
 import 'dart:async';
 import 'dart:io' as io;

 import 'package:args/command_runner.dart';
 import 'package:meta/meta.dart';
 import 'package:path/path.dart' as path;
 import 'package:test_core/src/runner/hack_register_platform.dart'
     as hack; // ignore: implementation_imports
 import 'package:test_api/src/backend/runtime.dart'; // ignore: implementation_imports
 import 'package:test_core/src/executable.dart'
     as test; // ignore: implementation_imports

 import 'environment.dart';
 import 'exceptions.dart';
 import 'integration_tests_manager.dart';
 import 'supported_browsers.dart';
 import 'test_platform.dart';
 import 'utils.dart';

 /// The type of tests requested by the tool user.
 enum TestTypesRequested {
   /// For running the unit tests only.
   unit,

   /// For running the integration tests only.
   integration,

   /// For running both unit and integration tests.
   all,
 }

 class TestCommand extends Command<bool> with ArgUtils {
   TestCommand() {
     argParser
       ..addFlag(
         'debug',
         help: 'Pauses the browser before running a test, giving you an '
             'opportunity to add breakpoints or inspect loaded code before '
             'running the code.',
       )
       ..addFlag(
         'unit-tests-only',
         defaultsTo: false,
         help: 'felt test command runs the unit tests and the integration tests '
             'at the same time. If this flag is set, only run the unit tests.',
       )
       ..addFlag(
         'integration-tests-only',
         defaultsTo: false,
         help: 'felt test command runs the unit tests and the integration tests '
             'at the same time. If this flag is set, only run the integration '
             'tests.',
       )
       ..addFlag('use-system-flutter',
         defaultsTo: false,
         help: 'integration tests are using flutter repository for various tasks'
         ', such as flutter drive, flutter pub get. If this flag is set, felt '
         'will use flutter command without cloning the repository. This flag '
         'can save internet bandwidth. However use with caution. Note that '
         'since flutter repo is always synced to youngest commit older than '
         'the engine commit for the tests running in CI, the tests results '
         'won\'t be consistent with CIs when this flag is set. flutter '
         'command should be set in the PATH for this flag to be useful.'
         'This flag can also be used to test local Flutter changes.'
       )
       ..addFlag(
         'update-screenshot-goldens',
         defaultsTo: false,
         help:
             'When running screenshot tests writes them to the file system into '
             '.dart_tool/goldens. Use this option to bulk-update all screenshots, '
             'for example, when a new browser version affects pixels.',
       )
       ..addOption(
         'browser',
         defaultsTo: 'chrome',
         help: 'An option to choose a browser to run the tests. Tests only work '
             ' on Chrome for now.',
       );

     SupportedBrowsers.instance.argParsers
         .forEach((t) => t.populateOptions(argParser));
   }

   @override
   final String name = 'test';

   @override
   final String description = 'Run tests.';

   TestTypesRequested testTypesRequested = null;

   /// Check the flags to see what type of tests are requested.
   TestTypesRequested findTestType() {
     if (boolArg('unit-tests-only') && boolArg('integration-tests-only')) {
       throw ArgumentError('Conflicting arguments: unit-tests-only and '
           'integration-tests-only are both set');
     } else if (boolArg('unit-tests-only')) {
       print('Running the unit tests only');
       return TestTypesRequested.unit;
     } else if (boolArg('integration-tests-only')) {
       if (!isChrome) {
         throw UnimplementedError(
             'Integration tests are only available on Chrome Desktop for now');
       }
       return TestTypesRequested.integration;
     } else {
       return TestTypesRequested.all;
     }
   }

   @override
   Future<bool> run() async {
     SupportedBrowsers.instance
       ..argParsers.forEach((t) => t.parseOptions(argResults));

     // Check the flags to see what type of integration tests are requested.
     testTypesRequested = findTestType();

     switch (testTypesRequested) {
       case TestTypesRequested.unit:
         return runUnitTests();
       case TestTypesRequested.integration:
         return runIntegrationTests();
       case TestTypesRequested.all:
         // TODO(nurhan): https://github.com/flutter/flutter/issues/53322
         // TODO(nurhan): Expand browser matrix for felt integration tests.
         if (runAllTests && isChrome) {
           bool unitTestResult = await runUnitTests();
           bool integrationTestResult = await runIntegrationTests();
           if (integrationTestResult != unitTestResult) {
             print('Tests run. Integration tests passed: $integrationTestResult '
                 'unit tests passed: $unitTestResult');
           }
           return integrationTestResult && unitTestResult;
         } else {
           return await runUnitTests();
         }
     }
     return false;
   }

   Future<bool> runIntegrationTests() async {
     return IntegrationTestsManager(browser, useSystemFlutter).runTests();
   }

   Future<bool> runUnitTests() async {
     _copyTestFontsIntoWebUi();
     await _buildHostPage();
     if (io.Platform.isWindows) {
       // On Dart 2.7 or greater, it gives an error for not
       // recognized "pub" version and asks for "pub" get.
       // See: https://github.com/dart-lang/sdk/issues/39738
       await _runPubGet();
     }

     await _buildTests(targets: targetFiles);

     // Many tabs will be left open after Safari runs, quit Safari during
     // cleanup.
     if (browser == 'safari') {
       cleanupCallbacks.add(() async {
         // Only close Safari if felt is running in CI environments. Do not close
         // Safari for the local testing.
         if (io.Platform.environment['LUCI_CONTEXT'] != null || isCirrus) {
           print('INFO: Safari tests ran. Quit Safari.');
           await runProcess(
             'sudo',
             ['pkill', '-lf', 'Safari'],
             workingDirectory: environment.webUiRootDir.path,
           );
         } else {
           print('INFO: Safari tests ran. Please quit Safari tabs.');
         }
       });
     }

     if (runAllTests) {
       await _runAllTests();
     } else {
       await _runTargetTests(targetFiles);
     }
     return true;
   }

   /// Whether to start the browser in debug mode.
   ///
   /// In this mode the browser pauses before running the test to allow
   /// you set breakpoints or inspect the code.
   bool get isDebug => boolArg('debug');

   /// Paths to targets to run, e.g. a single test.
   List<String> get targets => argResults.rest;

   /// The target test files to run.
   ///
   /// The value can be null if the developer prefers to run all the tests.
   List<FilePath> get targetFiles => (targets.isEmpty)
       ? null
       : targets.map((t) => FilePath.fromCwd(t)).toList();

   /// Whether all tests should run.
   bool get runAllTests => targets.isEmpty;

   /// The name of the browser to run tests in.
   String get browser => (argResults != null) ? stringArg('browser') : 'chrome';

   /// Whether [browser] is set to "chrome".
   bool get isChrome => browser == 'chrome';

   /// Use system flutter instead of cloning the repository.
   ///
   /// Read the flag help for more details. Uses PATH to locate flutter.
   bool get useSystemFlutter => boolArg('use-system-flutter');

   /// When running screenshot tests writes them to the file system into
   /// ".dart_tool/goldens".
   bool get doUpdateScreenshotGoldens => boolArg('update-screenshot-goldens');

   Future<void> _runTargetTests(List<FilePath> targets) async {
     await _runTestBatch(targets, concurrency: 1, expectFailure: false);
     _checkExitCode();
   }

   Future<void> _runAllTests() async {
     final io.Directory testDir = io.Directory(path.join(
       environment.webUiRootDir.path,
       'test',
     ));

     // Screenshot tests and smoke tests only run in Chrome.
     if (isChrome) {
       // Separate screenshot tests from unit-tests. Screenshot tests must run
       // one at a time. Otherwise, they will end up screenshotting each other.
       // This is not an issue for unit-tests.
       final FilePath failureSmokeTestPath = FilePath.fromWebUi(
         'test/golden_tests/golden_failure_smoke_test.dart',
       );
       final List<FilePath> screenshotTestFiles = <FilePath>[];
       final List<FilePath> unitTestFiles = <FilePath>[];

       for (io.File testFile
           in testDir.listSync(recursive: true).whereType<io.File>()) {
         final FilePath testFilePath = FilePath.fromCwd(testFile.path);
         if (!testFilePath.absolute.endsWith('_test.dart')) {
           // Not a test file at all. Skip.
           continue;
         }
         if (testFilePath == failureSmokeTestPath) {
           // A smoke test that fails on purpose. Skip.
           continue;
         }

         if (path.split(testFilePath.relativeToWebUi).contains('golden_tests')) {
           screenshotTestFiles.add(testFilePath);
         } else {
           unitTestFiles.add(testFilePath);
         }
       }

       // This test returns a non-zero exit code on purpose. Run it separately.
       if (io.Platform.environment['CIRRUS_CI'] != 'true') {
         await _runTestBatch(
           <FilePath>[failureSmokeTestPath],
           concurrency: 1,
           expectFailure: true,
         );
         _checkExitCode();
       }

       // Run all unit-tests as a single batch.
       await _runTestBatch(unitTestFiles, concurrency: 10, expectFailure: false);
       _checkExitCode();

       // Run screenshot tests one at a time.
       for (FilePath testFilePath in screenshotTestFiles) {
         await _runTestBatch(
           <FilePath>[testFilePath],
           concurrency: 1,
           expectFailure: false,
         );
         _checkExitCode();
       }
     } else {
       final List<FilePath> unitTestFiles = <FilePath>[];
       for (io.File testFile
           in testDir.listSync(recursive: true).whereType<io.File>()) {
         final FilePath testFilePath = FilePath.fromCwd(testFile.path);
         if (!testFilePath.absolute.endsWith('_test.dart')) {
           // Not a test file at all. Skip.
           continue;
         }
         if (!path
             .split(testFilePath.relativeToWebUi)
             .contains('golden_tests')) {
           unitTestFiles.add(testFilePath);
         }
       }
       // Run all unit-tests as a single batch.
       await _runTestBatch(unitTestFiles, concurrency: 10, expectFailure: false);
       _checkExitCode();
     }
   }

   void _checkExitCode() {
     if (io.exitCode != 0) {
       throw ToolException('Process exited with exit code ${io.exitCode}.');
     }
   }

   Future<void> _runPubGet() async {
     final int exitCode = await runProcess(
       environment.pubExecutable,
       <String>[
         'get',
       ],
       workingDirectory: environment.webUiRootDir.path,
     );

     if (exitCode != 0) {
       throw ToolException(
           'Failed to run pub get. Exited with exit code $exitCode');
     }
   }

   Future<void> _buildHostPage() async {
     final String hostDartPath = path.join('lib', 'static', 'host.dart');
     final io.File hostDartFile = io.File(path.join(
       environment.webEngineTesterRootDir.path,
       hostDartPath,
     ));
     final io.File timestampFile = io.File(path.join(
       environment.webEngineTesterRootDir.path,
       '$hostDartPath.js.timestamp',
     ));

     final String timestamp =
         hostDartFile.statSync().modified.millisecondsSinceEpoch.toString();
     if (timestampFile.existsSync()) {
       final String lastBuildTimestamp = timestampFile.readAsStringSync();
       if (lastBuildTimestamp == timestamp) {
         // The file is still fresh. No need to rebuild.
         return;
       } else {
         // Record new timestamp, but don't return. We need to rebuild.
         print('${hostDartFile.path} timestamp changed. Rebuilding.');
       }
     } else {
       print('Building ${hostDartFile.path}.');
     }

     final int exitCode = await runProcess(
       environment.dart2jsExecutable,
       <String>[
         hostDartPath,
         '-o',
         '$hostDartPath.js',
       ],
       workingDirectory: environment.webEngineTesterRootDir.path,
     );

     if (exitCode != 0) {
       throw ToolException('Failed to compile ${hostDartFile.path}. Compiler '
           'exited with exit code $exitCode');
     }

     // Record the timestamp to avoid rebuilding unless the file changes.
     timestampFile.writeAsStringSync(timestamp);
   }

   Future<void> _buildTests({List<FilePath> targets}) async {
     List<String> arguments = <String>[
       'run',
       'build_runner',
       'build',
       'test',
       '-o',
       'build',
       if (targets != null)
         for (FilePath path in targets) ...[
           '--build-filter=${path.relativeToWebUi}.js',
           '--build-filter=${path.relativeToWebUi}.browser_test.dart.js',
         ],
     ];
     final Stopwatch stopwatch = Stopwatch()..start();

     final int exitCode = await runProcess(
       environment.pubExecutable,
       arguments,
       workingDirectory: environment.webUiRootDir.path,
       environment: <String, String>{
         // This determines the number of concurrent dart2js processes.
         //
         // By default build_runner uses 4 workers.
         //
         // In a testing on a 32-core 132GB workstation increasing this number to
         // 32 sped up the build from ~4min to ~1.5min.
         if (io.Platform.environment.containsKey('BUILD_MAX_WORKERS_PER_TASK'))
           'BUILD_MAX_WORKERS_PER_TASK': io.Platform.environment['BUILD_MAX_WORKERS_PER_TASK'],
       },
     );
     stopwatch.stop();
     print('The build took ${stopwatch.elapsedMilliseconds ~/ 1000} seconds.');

     if (exitCode != 0) {
       throw ToolException(
           'Failed to compile tests. Compiler exited with exit code $exitCode');
     }
   }

   /// Runs a batch of tests.
   ///
   /// Unless [expectFailure] is set to false, sets [io.exitCode] to a non-zero value if any tests fail.
   Future<void> _runTestBatch(
     List<FilePath> testFiles, {
     @required int concurrency,
     @required bool expectFailure,
   }) async {
     final List<String> testArgs = <String>[
       ...<String>['-r', 'compact'],
       '--concurrency=$concurrency',
       if (isDebug) '--pause-after-load',
       '--platform=${SupportedBrowsers.instance.supportedBrowserToPlatform[browser]}',
       '--precompiled=${environment.webUiRootDir.path}/build',
       SupportedBrowsers.instance.browserToConfiguration[browser],
       '--',
       ...testFiles.map((f) => f.relativeToWebUi).toList(),
     ];

     hack.registerPlatformPlugin(<Runtime>[
       SupportedBrowsers.instance.supportedBrowsersToRuntimes[browser]
     ], () {
       return BrowserPlatform.start(
         browser,
         root: io.Directory.current.path,
         // It doesn't make sense to update a screenshot for a test that is expected to fail.
         doUpdateScreenshotGoldens: !expectFailure && doUpdateScreenshotGoldens,
       );
     });

     // We want to run tests with `web_ui` as a working directory.
     final dynamic backupCwd = io.Directory.current;
     io.Directory.current = environment.webUiRootDir.path;
     await test.main(testArgs);
     io.Directory.current = backupCwd;

     if (expectFailure) {
       if (io.exitCode != 0) {
         // It failed, as expected.
         io.exitCode = 0;
       } else {
         io.stderr.writeln(
           'Tests ${testFiles.join(', ')} did not fail. Expected failure.',
         );
         io.exitCode = 1;
       }
     }
   }
 }

 const List<String> _kTestFonts = <String>['ahem.ttf', 'Roboto-Regular.ttf'];

 void _copyTestFontsIntoWebUi() {
   final String fontsPath = path.join(
     environment.flutterDirectory.path,
     'third_party',
     'txt',
     'third_party',
     'fonts',
   );

   for (String fontFile in _kTestFonts) {
     final io.File sourceTtf = io.File(path.join(fontsPath, fontFile));
     final String destinationTtfPath =
         path.join(environment.webUiRootDir.path, 'lib', 'assets', fontFile);
     sourceTtf.copySync(destinationTtfPath);
   }
 }
	// Copyright 2013 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.

	// @dart = 2.6
	import 'dart:async';
	import 'dart:io' as io;

	import 'package:args/command_runner.dart';
	import 'package:meta/meta.dart';
	import 'package:path/path.dart' as path;
	import 'package:test_core/src/runner/hack_register_platform.dart'
	as hack; // ignore: implementation_imports
	import 'package:test_api/src/backend/runtime.dart'; // ignore: implementation_imports
	import 'package:test_core/src/executable.dart'
	as test; // ignore: implementation_imports

	import 'environment.dart';
	import 'exceptions.dart';
	import 'integration_tests_manager.dart';
	import 'supported_browsers.dart';
	import 'test_platform.dart';
	import 'utils.dart';

	/// The type of tests requested by the tool user.
	enum TestTypesRequested {
	/// For running the unit tests only.
	unit,

	/// For running the integration tests only.
	integration,

	/// For running both unit and integration tests.
	all,
	}

	class TestCommand extends Command<bool> with ArgUtils {
	TestCommand() {
	argParser
	..addFlag(
	'debug',
	help: 'Pauses the browser before running a test, giving you an '
	'opportunity to add breakpoints or inspect loaded code before '
	'running the code.',
	)
	..addFlag(
	'unit-tests-only',
	defaultsTo: false,
	help: 'felt test command runs the unit tests and the integration tests '
	'at the same time. If this flag is set, only run the unit tests.',
	)
	..addFlag(
	'integration-tests-only',
	defaultsTo: false,
	help: 'felt test command runs the unit tests and the integration tests '
	'at the same time. If this flag is set, only run the integration '
	'tests.',
	)
	..addFlag('use-system-flutter',
	defaultsTo: false,
	help: 'integration tests are using flutter repository for various tasks'
	', such as flutter drive, flutter pub get. If this flag is set, felt '
	'will use flutter command without cloning the repository. This flag '
	'can save internet bandwidth. However use with caution. Note that '
	'since flutter repo is always synced to youngest commit older than '
	'the engine commit for the tests running in CI, the tests results '
	'won\'t be consistent with CIs when this flag is set. flutter '
	'command should be set in the PATH for this flag to be useful.'
	'This flag can also be used to test local Flutter changes.'
	)
	..addFlag(
	'update-screenshot-goldens',
	defaultsTo: false,
	help:
	'When running screenshot tests writes them to the file system into '
	'.dart_tool/goldens. Use this option to bulk-update all screenshots, '
	'for example, when a new browser version affects pixels.',
	)
	..addOption(
	'browser',
	defaultsTo: 'chrome',
	help: 'An option to choose a browser to run the tests. Tests only work '
	' on Chrome for now.',
	);

	SupportedBrowsers.instance.argParsers
	.forEach((t) => t.populateOptions(argParser));
	}

	@override
	final String name = 'test';

	@override
	final String description = 'Run tests.';

	TestTypesRequested testTypesRequested = null;

	/// Check the flags to see what type of tests are requested.
	TestTypesRequested findTestType() {
	if (boolArg('unit-tests-only') && boolArg('integration-tests-only')) {
	throw ArgumentError('Conflicting arguments: unit-tests-only and '
	'integration-tests-only are both set');
	} else if (boolArg('unit-tests-only')) {
	print('Running the unit tests only');
	return TestTypesRequested.unit;
	} else if (boolArg('integration-tests-only')) {
	if (!isChrome) {
	throw UnimplementedError(
	'Integration tests are only available on Chrome Desktop for now');
	}
	return TestTypesRequested.integration;
	} else {
	return TestTypesRequested.all;
	}
	}

	@override
	Future<bool> run() async {
	SupportedBrowsers.instance
	..argParsers.forEach((t) => t.parseOptions(argResults));

	// Check the flags to see what type of integration tests are requested.
	testTypesRequested = findTestType();

	switch (testTypesRequested) {
	case TestTypesRequested.unit:
	return runUnitTests();
	case TestTypesRequested.integration:
	return runIntegrationTests();
	case TestTypesRequested.all:
	// TODO(nurhan): https://github.com/flutter/flutter/issues/53322
	// TODO(nurhan): Expand browser matrix for felt integration tests.
	if (runAllTests && isChrome) {
	bool unitTestResult = await runUnitTests();
	bool integrationTestResult = await runIntegrationTests();
	if (integrationTestResult != unitTestResult) {
	print('Tests run. Integration tests passed: $integrationTestResult '
	'unit tests passed: $unitTestResult');
	}
	return integrationTestResult && unitTestResult;
	} else {
	return await runUnitTests();
	}
	}
	return false;
	}

	Future<bool> runIntegrationTests() async {
	return IntegrationTestsManager(browser, useSystemFlutter).runTests();
	}

	Future<bool> runUnitTests() async {
	_copyTestFontsIntoWebUi();
	await _buildHostPage();
	if (io.Platform.isWindows) {
	// On Dart 2.7 or greater, it gives an error for not
	// recognized "pub" version and asks for "pub" get.
	// See: https://github.com/dart-lang/sdk/issues/39738
	await _runPubGet();
	}

	await _buildTests(targets: targetFiles);

	// Many tabs will be left open after Safari runs, quit Safari during
	// cleanup.
	if (browser == 'safari') {
	cleanupCallbacks.add(() async {
	// Only close Safari if felt is running in CI environments. Do not close
	// Safari for the local testing.
	if (io.Platform.environment['LUCI_CONTEXT'] != null \|\| isCirrus) {
	print('INFO: Safari tests ran. Quit Safari.');
	await runProcess(
	'sudo',
	['pkill', '-lf', 'Safari'],
	workingDirectory: environment.webUiRootDir.path,
	);
	} else {
	print('INFO: Safari tests ran. Please quit Safari tabs.');
	}
	});
	}

	if (runAllTests) {
	await _runAllTests();
	} else {
	await _runTargetTests(targetFiles);
	}
	return true;
	}

	/// Whether to start the browser in debug mode.
	///
	/// In this mode the browser pauses before running the test to allow
	/// you set breakpoints or inspect the code.
	bool get isDebug => boolArg('debug');

	/// Paths to targets to run, e.g. a single test.
	List<String> get targets => argResults.rest;

	/// The target test files to run.
	///
	/// The value can be null if the developer prefers to run all the tests.
	List<FilePath> get targetFiles => (targets.isEmpty)
	? null
	: targets.map((t) => FilePath.fromCwd(t)).toList();

	/// Whether all tests should run.
	bool get runAllTests => targets.isEmpty;

	/// The name of the browser to run tests in.
	String get browser => (argResults != null) ? stringArg('browser') : 'chrome';

	/// Whether [browser] is set to "chrome".
	bool get isChrome => browser == 'chrome';

	/// Use system flutter instead of cloning the repository.
	///
	/// Read the flag help for more details. Uses PATH to locate flutter.
	bool get useSystemFlutter => boolArg('use-system-flutter');

	/// When running screenshot tests writes them to the file system into
	/// ".dart_tool/goldens".
	bool get doUpdateScreenshotGoldens => boolArg('update-screenshot-goldens');

	Future<void> _runTargetTests(List<FilePath> targets) async {
	await _runTestBatch(targets, concurrency: 1, expectFailure: false);
	_checkExitCode();
	}

	Future<void> _runAllTests() async {
	final io.Directory testDir = io.Directory(path.join(
	environment.webUiRootDir.path,
	'test',
	));

	// Screenshot tests and smoke tests only run in Chrome.
	if (isChrome) {
	// Separate screenshot tests from unit-tests. Screenshot tests must run
	// one at a time. Otherwise, they will end up screenshotting each other.
	// This is not an issue for unit-tests.
	final FilePath failureSmokeTestPath = FilePath.fromWebUi(
	'test/golden_tests/golden_failure_smoke_test.dart',
	);
	final List<FilePath> screenshotTestFiles = <FilePath>[];
	final List<FilePath> unitTestFiles = <FilePath>[];

	for (io.File testFile
	in testDir.listSync(recursive: true).whereType<io.File>()) {
	final FilePath testFilePath = FilePath.fromCwd(testFile.path);
	if (!testFilePath.absolute.endsWith('_test.dart')) {
	// Not a test file at all. Skip.
	continue;
	}
	if (testFilePath == failureSmokeTestPath) {
	// A smoke test that fails on purpose. Skip.
	continue;
	}

	if (path.split(testFilePath.relativeToWebUi).contains('golden_tests')) {
	screenshotTestFiles.add(testFilePath);
	} else {
	unitTestFiles.add(testFilePath);
	}
	}

	// This test returns a non-zero exit code on purpose. Run it separately.
	if (io.Platform.environment['CIRRUS_CI'] != 'true') {
	await _runTestBatch(
	<FilePath>[failureSmokeTestPath],
	concurrency: 1,
	expectFailure: true,
	);
	_checkExitCode();
	}

	// Run all unit-tests as a single batch.
	await _runTestBatch(unitTestFiles, concurrency: 10, expectFailure: false);
	_checkExitCode();

	// Run screenshot tests one at a time.
	for (FilePath testFilePath in screenshotTestFiles) {
	await _runTestBatch(
	<FilePath>[testFilePath],
	concurrency: 1,
	expectFailure: false,
	);
	_checkExitCode();
	}
	} else {
	final List<FilePath> unitTestFiles = <FilePath>[];
	for (io.File testFile
	in testDir.listSync(recursive: true).whereType<io.File>()) {
	final FilePath testFilePath = FilePath.fromCwd(testFile.path);
	if (!testFilePath.absolute.endsWith('_test.dart')) {
	// Not a test file at all. Skip.
	continue;
	}
	if (!path
	.split(testFilePath.relativeToWebUi)
	.contains('golden_tests')) {
	unitTestFiles.add(testFilePath);
	}
	}
	// Run all unit-tests as a single batch.
	await _runTestBatch(unitTestFiles, concurrency: 10, expectFailure: false);
	_checkExitCode();
	}
	}

	void _checkExitCode() {
	if (io.exitCode != 0) {
	throw ToolException('Process exited with exit code ${io.exitCode}.');
	}
	}

	Future<void> _runPubGet() async {
	final int exitCode = await runProcess(
	environment.pubExecutable,
	<String>[
	'get',
	],
	workingDirectory: environment.webUiRootDir.path,
	);

	if (exitCode != 0) {
	throw ToolException(
	'Failed to run pub get. Exited with exit code $exitCode');
	}
	}

	Future<void> _buildHostPage() async {
	final String hostDartPath = path.join('lib', 'static', 'host.dart');
	final io.File hostDartFile = io.File(path.join(
	environment.webEngineTesterRootDir.path,
	hostDartPath,
	));
	final io.File timestampFile = io.File(path.join(
	environment.webEngineTesterRootDir.path,
	'$hostDartPath.js.timestamp',
	));

	final String timestamp =
	hostDartFile.statSync().modified.millisecondsSinceEpoch.toString();
	if (timestampFile.existsSync()) {
	final String lastBuildTimestamp = timestampFile.readAsStringSync();
	if (lastBuildTimestamp == timestamp) {
	// The file is still fresh. No need to rebuild.
	return;
	} else {
	// Record new timestamp, but don't return. We need to rebuild.
	print('${hostDartFile.path} timestamp changed. Rebuilding.');
	}
	} else {
	print('Building ${hostDartFile.path}.');
	}

	final int exitCode = await runProcess(
	environment.dart2jsExecutable,
	<String>[
	hostDartPath,
	'-o',
	'$hostDartPath.js',
	],
	workingDirectory: environment.webEngineTesterRootDir.path,
	);

	if (exitCode != 0) {
	throw ToolException('Failed to compile ${hostDartFile.path}. Compiler '
	'exited with exit code $exitCode');
	}

	// Record the timestamp to avoid rebuilding unless the file changes.
	timestampFile.writeAsStringSync(timestamp);
	}

	Future<void> _buildTests({List<FilePath> targets}) async {
	List<String> arguments = <String>[
	'run',
	'build_runner',
	'build',
	'test',
	'-o',
	'build',
	if (targets != null)
	for (FilePath path in targets) ...[
	'--build-filter=${path.relativeToWebUi}.js',
	'--build-filter=${path.relativeToWebUi}.browser_test.dart.js',
	],
	];
	final Stopwatch stopwatch = Stopwatch()..start();

	final int exitCode = await runProcess(
	environment.pubExecutable,
	arguments,
	workingDirectory: environment.webUiRootDir.path,
	environment: <String, String>{
	// This determines the number of concurrent dart2js processes.
	//
	// By default build_runner uses 4 workers.
	//
	// In a testing on a 32-core 132GB workstation increasing this number to
	// 32 sped up the build from ~4min to ~1.5min.
	if (io.Platform.environment.containsKey('BUILD_MAX_WORKERS_PER_TASK'))
	'BUILD_MAX_WORKERS_PER_TASK': io.Platform.environment['BUILD_MAX_WORKERS_PER_TASK'],
	},
	);
	stopwatch.stop();
	print('The build took ${stopwatch.elapsedMilliseconds ~/ 1000} seconds.');

	if (exitCode != 0) {
	throw ToolException(
	'Failed to compile tests. Compiler exited with exit code $exitCode');
	}
	}

	/// Runs a batch of tests.
	///
	/// Unless [expectFailure] is set to false, sets [io.exitCode] to a non-zero value if any tests fail.
	Future<void> _runTestBatch(
	List<FilePath> testFiles, {
	@required int concurrency,
	@required bool expectFailure,
	}) async {
	final List<String> testArgs = <String>[
	...<String>['-r', 'compact'],
	'--concurrency=$concurrency',
	if (isDebug) '--pause-after-load',
	'--platform=${SupportedBrowsers.instance.supportedBrowserToPlatform[browser]}',
	'--precompiled=${environment.webUiRootDir.path}/build',
	SupportedBrowsers.instance.browserToConfiguration[browser],
	'--',
	...testFiles.map((f) => f.relativeToWebUi).toList(),
	];

	hack.registerPlatformPlugin(<Runtime>[
	SupportedBrowsers.instance.supportedBrowsersToRuntimes[browser]
	], () {
	return BrowserPlatform.start(
	browser,
	root: io.Directory.current.path,
	// It doesn't make sense to update a screenshot for a test that is expected to fail.
	doUpdateScreenshotGoldens: !expectFailure && doUpdateScreenshotGoldens,
	);
	});

	// We want to run tests with `web_ui` as a working directory.
	final dynamic backupCwd = io.Directory.current;
	io.Directory.current = environment.webUiRootDir.path;
	await test.main(testArgs);
	io.Directory.current = backupCwd;

	if (expectFailure) {
	if (io.exitCode != 0) {
	// It failed, as expected.
	io.exitCode = 0;
	} else {
	io.stderr.writeln(
	'Tests ${testFiles.join(', ')} did not fail. Expected failure.',
	);
	io.exitCode = 1;
	}
	}
	}
	}

	const List<String> _kTestFonts = <String>['ahem.ttf', 'Roboto-Regular.ttf'];

	void _copyTestFontsIntoWebUi() {
	final String fontsPath = path.join(
	environment.flutterDirectory.path,
	'third_party',
	'txt',
	'third_party',
	'fonts',
	);

	for (String fontFile in _kTestFonts) {
	final io.File sourceTtf = io.File(path.join(fontsPath, fontFile));
	final String destinationTtfPath =
	path.join(environment.webUiRootDir.path, 'lib', 'assets', fontFile);
	sourceTtf.copySync(destinationTtfPath);
	}
	}