[web] Add Edge support for Flutter Engine unit-tests. (flutter/engine#15641)

* Add Edge support for Flutter Engine unit-tests. This does not include the launcher

* Add mapping from browser name to platform.

* remove ie from supported browser maps

engine/src/flutter/lib/web_ui/dart_test_edge.yaml

@@ -0,0 +1,7 @@
+# For more information on test and runner configurations:
+#
+# * https://github.com/dart-lang/test/blob/master/pkgs/test/doc/configuration.md#platforms
+
+platforms:
+  - ie
+  - vm

engine/src/flutter/lib/web_ui/dev/common.dart

@@ -51,6 +51,7 @@ abstract class PlatformBinding {
   String getFirefoxExecutablePath(io.Directory versionDir);
   String getFirefoxLatestVersionUrl();
   String getSafariSystemExecutablePath();
+  String getCommandToRunEdge();
 }
 
 const String _kBaseDownloadUrl =
@@ -86,6 +87,12 @@ class _WindowsBinding implements PlatformBinding {
   @override
   String getSafariSystemExecutablePath() =>
       throw UnsupportedError('Safari is not supported on Windows');
+
+  // TODO(nurhan): Add code to check and install MicrosoftEdgeLauncher
+  // if missing.
+  // See: https://github.com/flutter/flutter/issues/48823
+  @override
+  String getCommandToRunEdge() => 'MicrosoftEdgeLauncher';
 }
 
 class _LinuxBinding implements PlatformBinding {
@@ -118,6 +125,10 @@ class _LinuxBinding implements PlatformBinding {
   @override
   String getSafariSystemExecutablePath() =>
       throw UnsupportedError('Safari is not supported on Linux');
+
+  @override
+  String getCommandToRunEdge() =>
+      throw UnsupportedError('Edge is not supported on Linux');
 }
 
 class _MacBinding implements PlatformBinding {
@@ -155,6 +166,10 @@ class _MacBinding implements PlatformBinding {
   @override
   String getSafariSystemExecutablePath() =>
       '/Applications/Safari.app/Contents/MacOS/Safari';
+
+  @override
+  String getCommandToRunEdge() =>
+      throw UnimplementedError('Tests for Edge are not implemented for MacOS.');
 }
 
 class BrowserInstallation {

engine/src/flutter/lib/web_ui/dev/edge.dart

@@ -0,0 +1,53 @@
+// 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.
+
+import 'dart:async';
+import 'dart:io';
+
+import 'browser.dart';
+import 'common.dart';
+import 'edge_installation.dart';
+
+/// A class for running an instance of Edge.
+///
+/// Most of the communication with the browser is expected to happen via HTTP,
+/// so this exposes a bare-bones API. The browser starts as soon as the class is
+/// constructed, and is killed when [close] is called.
+///
+/// Any errors starting or running the process are reported through [onExit].
+class Edge extends Browser {
+  @override
+  final name = 'Edge';
+
+  static String version;
+
+  /// Starts a new instance of Safari open to the given [url], which may be a
+  /// [Uri] or a [String].
+  factory Edge(Uri url, {bool debug = false}) {
+    version = EdgeArgParser.instance.version;
+
+    assert(version != null);
+    return Edge._(() async {
+      // TODO(nurhan): Configure info log for LUCI.
+      final BrowserInstallation installation = await getEdgeInstallation(
+        version,
+        infoLog: DevNull(),
+      );
+
+      // Debug is not a valid option for Edge. Remove it.
+      String pathToOpen = url.toString();
+      if(pathToOpen.contains('debug')) {
+        int index = pathToOpen.indexOf('debug');
+        pathToOpen = pathToOpen.substring(0, index-1);
+      }
+
+      var process =
+          await Process.start(installation.executable, ['$pathToOpen','-k']);
+
+      return process;
+    });
+  }
+
+  Edge._(Future<Process> startBrowser()) : super(startBrowser);
+}

engine/src/flutter/lib/web_ui/dev/edge_installation.dart

@@ -0,0 +1,79 @@
+// 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.
+
+import 'dart:async';
+import 'dart:io' as io;
+
+import 'package:args/args.dart';
+
+import 'common.dart';
+
+class EdgeArgParser extends BrowserArgParser {
+  static final EdgeArgParser _singletonInstance = EdgeArgParser._();
+
+  /// The [EdgeArgParser] singleton.
+  static EdgeArgParser get instance => _singletonInstance;
+
+  String _version;
+
+  EdgeArgParser._();
+
+  @override
+  void populateOptions(ArgParser argParser) {
+    argParser
+      ..addOption(
+        'edge-version',
+        defaultsTo: 'system',
+        help: 'The Edge version to use while running tests. The Edge '
+            'browser installed on the system is used as the only option now.',
+      );
+  }
+
+  @override
+  void parseOptions(ArgResults argResults) {
+    _version = argResults['edge-version'];
+    assert(_version == 'system');
+  }
+
+  @override
+  String get version => _version;
+}
+
+/// Returns the installation of Edge.
+///
+/// Currently uses the Edge version installed on the operating system.
+///
+/// As explained on the Microsoft help page: `Microsoft Edge comes
+/// exclusively with Windows 10 and cannot be downloaded or installed separately.`
+/// See: https://support.microsoft.com/en-us/help/17171/microsoft-edge-get-to-know
+///
+// TODO(nurhan): Investigate running tests for the tech preview downloads
+// from the beta channel.
+Future<BrowserInstallation> getEdgeInstallation(
+  String requestedVersion, {
+  StringSink infoLog,
+}) async {
+  // For now these tests are aimed to run only on Windows machines local or on LUCI/CI.
+  // In the future we can investigate to run them on Android or on MacOS.
+  if (!io.Platform.isWindows) {
+    throw UnimplementedError(
+        'Tests for Edge on ${io.Platform.operatingSystem} is'
+        ' not supported.');
+  }
+
+  infoLog ??= io.stdout;
+
+  if (requestedVersion == 'system') {
+    // Since Edge is included in Windows, always assume there will be one on the
+    // system.
+    infoLog.writeln('Using the system version that is already installed.');
+    return BrowserInstallation(
+      version: 'system',
+      executable: PlatformBinding.instance.getCommandToRunEdge(),
+    );
+  } else {
+    infoLog.writeln('Unsupported version $requestedVersion.');
+    throw UnimplementedError();
+  }
+}

engine/src/flutter/lib/web_ui/dev/supported_browsers.dart

@@ -8,7 +8,9 @@ import 'browser.dart';
 import 'chrome.dart';
 import 'chrome_installer.dart';
 import 'common.dart';
+import 'edge.dart';
 import 'environment.dart';
+import 'edge_installation.dart';
 import 'firefox.dart';
 import 'firefox_installer.dart';
 import 'safari.dart';
@@ -23,21 +25,43 @@ import 'safari_installation.dart';
 ///
 /// One should also implement [BrowserArgParser] and add it to the [argParsers].
 class SupportedBrowsers {
-  final List<BrowserArgParser> argParsers =
-      List.of([ChromeArgParser.instance, FirefoxArgParser.instance, SafariArgParser.instance]);
+  final List<BrowserArgParser> argParsers = List.of([
+    ChromeArgParser.instance,
+    EdgeArgParser.instance,
+    FirefoxArgParser.instance,
+    SafariArgParser.instance
+  ]);
 
-  final List<String> supportedBrowserNames = ['chrome', 'firefox', 'safari'];
+  final List<String> supportedBrowserNames = [
+    'chrome',
+    'edge',
+    'firefox',
+    'safari'
+  ];
 
   final Map<String, Runtime> supportedBrowsersToRuntimes = {
     'chrome': Runtime.chrome,
+    'edge': Runtime.internetExplorer,
     'firefox': Runtime.firefox,
     'safari': Runtime.safari,
   };
 
+  final Map<String, String> supportedBrowserToPlatform = {
+    'chrome': 'chrome',
+    'edge': 'ie',
+    'firefox': 'firefox',
+    'safari': 'safari',
+  };
+
   final Map<String, String> browserToConfiguration = {
-    'chrome': '--configuration=${environment.webUiRootDir.path}/dart_test_chrome.yaml',
-    'firefox': '--configuration=${environment.webUiRootDir.path}/dart_test_firefox.yaml',
-    'safari': '--configuration=${environment.webUiRootDir.path}/dart_test_safari.yaml',
+    'chrome':
+        '--configuration=${environment.webUiRootDir.path}/dart_test_chrome.yaml',
+    'edge':
+        '--configuration=${environment.webUiRootDir.path}/dart_test_edge.yaml',
+    'firefox':
+        '--configuration=${environment.webUiRootDir.path}/dart_test_firefox.yaml',
+    'safari':
+        '--configuration=${environment.webUiRootDir.path}/dart_test_safari.yaml',
   };
 
   static final SupportedBrowsers _singletonInstance = SupportedBrowsers._();
@@ -48,8 +72,10 @@ class SupportedBrowsers {
   SupportedBrowsers._();
 
   Browser getBrowser(Runtime runtime, Uri url, {bool debug = false}) {
-    if (runtime ==  Runtime.chrome) {
+    if (runtime == Runtime.chrome) {
       return Chrome(url, debug: debug);
+    } else if (runtime == Runtime.internetExplorer) {
+      return Edge(url, debug: debug);
     } else if (runtime == Runtime.firefox) {
       return Firefox(url, debug: debug);
     } else if (runtime == Runtime.safari) {

engine/src/flutter/lib/web_ui/dev/test_runner.dart

@@ -250,9 +250,7 @@ class TestCommand extends Command<bool> {
   }
 
   Future<void> _buildTests({List<FilePath> targets}) async {
-    final int exitCode = await runProcess(
-      environment.pubExecutable,
-      <String>[
+    List<String> arguments = <String>[
         'run',
         'build_runner',
         'build',
@@ -264,7 +262,10 @@ class TestCommand extends Command<bool> {
             '--build-filter=${path.relativeToWebUi}.js',
             '--build-filter=${path.relativeToWebUi}.browser_test.dart.js',
           ],
-      ],
+      ];
+    final int exitCode = await runProcess(
+      environment.pubExecutable,
+      arguments,
       workingDirectory: environment.webUiRootDir.path,
     );
 
@@ -287,7 +288,7 @@ class TestCommand extends Command<bool> {
       ...<String>['-r', 'compact'],
       '--concurrency=$concurrency',
       if (isDebug) '--pause-after-load',
-      '--platform=$browser',
+      '--platform=${SupportedBrowsers.instance.supportedBrowserToPlatform[browser]}',
       '--precompiled=${environment.webUiRootDir.path}/build',
       SupportedBrowsers.instance.browserToConfiguration[browser],
       '--',