Support re-running tests while debugging.

lib/src/runner/console.dart

+// 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);
+}