Support re-running tests while debugging.

When the browser is paused at a breakpoint, the runner will now open a
command-line console with a "restart" command that will restart the
current test.

This currently has no tests, due to dart-lang/sdk#25369 and the lack of
a programmatic API for interacting with Observatory. I've tested it
reasonably thoroughly by hand, but it's more likely than the average
feature to have lurking bugs.

Closes #335

[email protected]

Review URL: https://codereview.chromium.org//1561073003 .

Author: nex3

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## 0.12.7
 
+* Add the ability to re-run tests while debugging. When the browser is paused at
+  a breakpoint, the test runner will open an interactive console on the command
+  line that can be used to restart the test.
+
 * Add the ability to tag tests. Tests with specific tags may be run by passing
   the `--tags` command-line argument, or excluded by passing the
   `--exclude-tags` parameter.
@@ -11,7 +15,7 @@
 [focusing]: http://jasmine.github.io/2.1/focused_specs.html
 [issue 16]: https://github.com/dart-lang/test/issues/16
 
-## 0.12.6+1
+## 0.12.6+2
 
 * Declare compatibility with `http_parser` 2.0.0.
 

lib/src/backend/live_test.dart

@@ -115,6 +115,9 @@ abstract class LiveTest {
     return test.name.substring(group.name.length + 1);
   }
 
+  /// Loads a copy of this [LiveTest] that's able to be run again.
+  LiveTest copy() => test.load(suite, groups: groups);
+
   /// Signals that this test should start running as soon as possible.
   ///
   /// A test may not start running immediately for various reasons specific to

lib/src/runner.dart

@@ -16,6 +16,7 @@ import 'backend/test.dart';
 import 'backend/test_platform.dart';
 import 'runner/application_exception.dart';
 import 'runner/configuration.dart';
+import 'runner/debugger.dart';
 import 'runner/engine.dart';
 import 'runner/load_exception.dart';
 import 'runner/load_suite.dart';
@@ -24,7 +25,6 @@ import 'runner/reporter.dart';
 import 'runner/reporter/compact.dart';
 import 'runner/reporter/expanded.dart';
 import 'runner/reporter/json.dart';
-import 'runner/runner_suite.dart';
 import 'util/io.dart';
 import 'utils.dart';
 
@@ -56,6 +56,11 @@ class Runner {
   /// on multiple platforms.
   final _tagWarningSuites = new Set<String>();
 
+  /// The current debug operation, if any.
+  ///
+  /// This is stored so that we can cancel it when the runner is closed.
+  CancelableOperation _debugOperation;
+
   /// The memoizer for ensuring [close] only runs once.
   final _closeMemo = new AsyncMemoizer();
   bool get _closed => _closeMemo.hasRun;
@@ -156,6 +161,8 @@ class Runner {
       });
     }
 
+    if (_debugOperation != null) await _debugOperation.cancel();
+
     if (_suiteSubscription != null) _suiteSubscription.cancel();
     _suiteSubscription = null;
 
@@ -290,18 +297,8 @@ class Runner {
     }
 
     _suiteSubscription = suites.asyncMap((loadSuite) async {
-      // Make the underlying suite null so that the engine doesn't start running
-      // it immediately.
-      _engine.suiteSink.add(loadSuite.changeSuite((_) => null));
-
-      var suite = await loadSuite.suite;
-      if (suite == null) return;
-
-      await _pause(suite);
-      if (_closed) return;
-
-      _engine.suiteSink.add(suite);
-      await _engine.onIdle.first;
+      _debugOperation = debug(_config, _engine, _reporter, loadSuite);
+      await _debugOperation.valueOrCancellation();
     }).listen(null);
 
     var results = await Future.wait([
@@ -310,63 +307,4 @@ class Runner {
     ]);
     return results.last;
   }
-
-  /// Pauses the engine and the reporter so that the user can set breakpoints as
-  /// necessary.
-  ///
-  /// This is a no-op for test suites that aren't on platforms where debugging
-  /// is supported.
-  Future _pause(RunnerSuite suite) async {
-    if (suite.platform == null) return;
-    if (suite.platform == TestPlatform.vm) return;
-
-    try {
-      _reporter.pause();
-
-      var bold = _config.color ? '\u001b[1m' : '';
-      var yellow = _config.color ? '\u001b[33m' : '';
-      var noColor = _config.color ? '\u001b[0m' : '';
-      print('');
-
-      if (suite.platform.isDartVM) {
-        var url = suite.environment.observatoryUrl;
-        if (url == null) {
-          print("${yellow}Observatory URL not found. Make sure you're using "
-              "${suite.platform.name} 1.11 or later.$noColor");
-        } else {
-          print("Observatory URL: $bold$url$noColor");
-        }
-      }
-
-      if (suite.platform.isHeadless) {
-        var url = suite.environment.remoteDebuggerUrl;
-        if (url == null) {
-          print("${yellow}Remote debugger URL not found.$noColor");
-        } else {
-          print("Remote debugger URL: $bold$url$noColor");
-        }
-      }
-
-      var buffer = new StringBuffer(
-          "${bold}The test runner is paused.${noColor} ");
-      if (!suite.platform.isHeadless) {
-        buffer.write("Open the dev console in ${suite.platform} ");
-      } else {
-        buffer.write("Open the remote debugger ");
-      }
-      if (suite.platform.isDartVM) buffer.write("or the Observatory ");
-
-      buffer.write("and set breakpoints. Once you're finished, return to this "
-          "terminal and press Enter.");
-
-      print(wordWrap(buffer.toString()));
-
-      await inCompletionOrder([
-        suite.environment.displayPause(),
-        cancelableNext(stdinLines)
-      ]).first;
-    } finally {
-      _reporter.resume();
-    }
-  }
 }

lib/src/runner/browser/iframe_test.dart

@@ -13,6 +13,7 @@ import '../../backend/state.dart';
 import '../../backend/suite.dart';
 import '../../backend/test.dart';
 import '../../backend/test_platform.dart';
+import '../../utils.dart';
 import '../../util/multi_channel.dart';
 import '../../util/remote_exception.dart';
 import '../../util/stack_trace_mapper.dart';
@@ -63,13 +64,27 @@ class IframeTest extends Test {
           assert(message['type'] == 'complete');
           controller.completer.complete();
         }
+      }, onDone: () {
+        // When the test channel closes—presumably becuase the browser
+        // closed—mark the test as complete no matter what.
+        if (controller.completer.isCompleted) return;
+        controller.completer.complete();
       });
     }, () {
-      // Ignore all future messages from the test and complete it immediately.
-      // We don't need to tell it to run its tear-down because there's nothing a
-      // browser test needs to clean up on the file system anyway.
-      testChannel.sink.close();
-      if (!controller.completer.isCompleted) controller.completer.complete();
+      // If the test has finished running, just disconnect the channel.
+      if (controller.completer.isCompleted) {
+        testChannel.sink.close();
+        return;
+      }
+
+      invoke(() async {
+        // If the test is still running, send it a message telling it to shut
+        // down ASAP. This causes the [Invoker] to eagerly throw exceptions
+        // whenever the test touches it.
+        testChannel.sink.add({'command': 'close'});
+        await controller.completer.future;
+        testChannel.sink.close();
+      });
     }, groups: groups);
     return controller.liveTest;
   }

lib/src/runner/console.dart

@@ -0,0 +1,120 @@
+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library test.runner.console;
+
+import 'dart:io';
+import 'dart:math' as math;
+
+import 'package:async/async.dart';
+
+import '../util/io.dart';
+import '../utils.dart';
+
+/// An interactive console for taking user commands.
+class Console {
+  /// The registered commands.
+  final _commands = <String, _Command>{};
+
+  /// The pending next line of standard input, if we're waiting on one.
+  CancelableOperation _nextLine;
+
+  /// Whether the console is currently running.
+  bool _running = false;
+
+  /// The terminal escape for red text, or the empty string if this is Windows
+  /// or not outputting to a terminal.
+  final String _red;
+
+  /// The terminal escape for bold text, or the empty string if this is
+  /// Windows or not outputting to a terminal.
+  final String _bold;
+
+  /// The terminal escape for removing test coloring, or the empty string if
+  /// this is Windows or not outputting to a terminal.
+  final String _noColor;
+
+  /// Creates a new [Console].
+  ///
+  /// If [color] is true, this uses Unix terminal colors.
+  Console({bool color: true})
+      : _red = color ? '\u001b[31m' : '',
+        _bold = color ? '\u001b[1m' : '',
+        _noColor = color ? '\u001b[0m' : '' {
+    registerCommand("help", "Displays this help information.", _displayHelp);
+  }
+
+  /// Registers a command to be run whenever the user types [name].
+  ///
+  /// The [description] should be a one-line description of the command to print
+  /// in the help output. The [body] callback will be called when the user types
+  /// the command, and may return a [Future].
+  void registerCommand(String name, String description, body()) {
+    if (_commands.containsKey(name)) {
+      throw new ArgumentError(
+          'The console already has a command named "$name".');
+    }
+
+    _commands[name] = new _Command(name, description, body);
+  }
+
+  /// Starts running the console.
+  ///
+  /// This prints the initial prompt and loops while waiting for user input.
+  void start() {
+    _running = true;
+    invoke(() async {
+      while (_running) {
+        stdout.write("> ");
+        _nextLine = cancelableNext(stdinLines);
+        var commandName = await _nextLine.value;
+        _nextLine = null;
+
+        var command = _commands[commandName];
+        if (command == null) {
+          stderr.writeln(
+              "${_red}Unknown command $_bold$commandName$_noColor$_red."
+                "$_noColor");
+        } else {
+          await command.body();
+        }
+      }
+    });
+  }
+
+  /// Stops the console running.
+  void stop() {
+    _running = false;
+    if (_nextLine != null) {
+      stdout.writeln();
+      _nextLine.cancel();
+    }
+  }
+
+  /// Displays the help info for the console commands.
+  void _displayHelp() {
+    var maxCommandLength = _commands.values
+        .map((command) => command.name.length)
+        .reduce(math.max);
+
+    for (var command in _commands.values) {
+      var name = command.name.padRight(maxCommandLength + 4);
+      print("$_bold$name$_noColor${command.description}");
+    }
+  }
+}
+
+/// An individual console command.
+class _Command {
+  /// The name of the command.
+  final String name;
+
+  /// The single-line description of the command.
+  final String description;
+
+  /// The callback to run when the command is invoked.
+  final Function body;
+
+  _Command(this.name, this.description, this.body);
+}