Add a ConsoleReporter for printing human-friendly test progress reports.

lib/src/console_reporter.dart

Index: lib/src/console_reporter.dart
diff --git a/lib/src/console_reporter.dart b/lib/src/console_reporter.dart
new file mode 100644
index 0000000000000000000000000000000000000000..3faa1b47579b3d98049918a4d91e48a5efef5707
--- /dev/null
+++ b/lib/src/console_reporter.dart
@@ -0,0 +1,205 @@
+// Copyright (c) 2015, 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 unittest.console_reporter;
+
+import 'dart:async';
+import 'dart:io';
+
+import 'engine.dart';
+import 'io.dart';
+import 'live_test.dart';
+import 'state.dart';
+import 'suite.dart';
+import 'utils.dart';
+
+/// The terminal escape for green text, or the empty string if this is Windows
+/// or not outputting to a terminal.
+final _green = getSpecial('\u001b[32m');
+
+/// The terminal escape for red text, or the empty string if this is Windows or
+/// not outputting to a terminal.
+final _red = getSpecial('\u001b[31m');
+
+/// The terminal escape for removing test coloring, or the empty string if this
+/// is Windows or not outputting to a terminal.
+final _noColor = getSpecial('\u001b[0m');
+
+/// The maximum console line length.
+///
+/// Lines longer than this will be cropped.
+const _lineLength = 80;
+
+/// A reporter that prints test results to the console in a single
+/// continuously-updating line.
+class ConsoleReporter {
+  /// The engine used to run the tests.
+  final Engine _engine;
+
+  /// Whether multiple test suites are being run.
+  final bool _multipleSuites;
+
+  /// A stopwatch that tracks the duration of the full run.
+  final _stopwatch = new Stopwatch();
+
+  /// The set of tests that have completed and been marked as passing.
+  final _passed = new Set<LiveTest>();
+
+  /// The set of tests that have completed and been marked as failing or error.
+  final _failed = new Set<LiveTest>();
+
+  /// Creates a [ConsoleReporter] that will run all tests in [suites].
+  ConsoleReporter(Iterable<Suite> suites)
+      : _multipleSuites = suites.length > 1,

[kevmoo, 2015/02/11 22:37:39]

I hate length checks against Iterable -> causes a full enumeration

Could _multipleSuites be a property off Engine.liveTests.length?

[nweiz, 2015/02/11 23:34:43]

Not really, since Engine.liveTests flattens across suites. You'd have to iterate
through and manually count the suites, which would be way worse than just
enumerating once here.

+        _engine = new Engine(suites) {
+
+    _engine.onTestStarted.listen((liveTest) {
+      _progressLine(_description(liveTest));
+      liveTest.onStateChange.listen((state) {
+        if (state.status != Status.complete) return;
+        if (state.result == Result.success) {
+          _passed.add(liveTest);
+        } else {
+          _passed.remove(liveTest);
+          _failed.add(liveTest);
+        }
+        _progressLine(_description(liveTest));
+      });
+
+      liveTest.onError.listen((error) {
+        if (liveTest.state.status != Status.complete) return;
+
+        // TODO(nweiz): don't re-print the progress line if a test has multiple
+        // errors in a row.
+        _progressLine(_description(liveTest));
+        print('');
+        print(indent("${error.error}\n${error.stackTrace}"));
+      });
+    });
+  }
+
+  /// Runs all tests in all provided suites.
+  ///
+  /// This returns `true` if all tests succeed, and `false` otherwise. It will
+  /// only return once all tests have finished running.
+  Future<bool> run() {
+    if (_stopwatch.isRunning) {
+      throw new StateError("ConsoleReporter.run() may not be called more than "
+          "once.");
+    }
+
+    _stopwatch.start();
+    return _engine.run().then((success) {
+      if (_engine.liveTests.isEmpty) {
+        print("\nNo tests ran.");
+      } else if (success) {
+        _progressLine("All tests passed!");
+        print('');
+      } else {
+        _progressLine('Some tests failed.', color: _red);
+        print('');
+      }
+
+      return success;
+    });
+  }
+
+  /// Prints a line representing the current state of the tests.
+  ///
+  /// [message] goes after the progress report, and may be truncated to fit the
+  /// entire line within [_lineLength]. If [color] is passed, it's used as the
+  /// color for [message].
+  void _progressLine(String message, {String color}) {
+    if (color == null) color = '';
+    var duration = _stopwatch.elapsed;
+    var buffer = new StringBuffer();
+
+    // \r moves back to the beginning of the current line.
+    buffer.write('\r${_timeString(duration)} ');
+    buffer.write(_green);
+    buffer.write('+');
+    buffer.write(_passed.length);
+    buffer.write(_noColor);
+
+    if (_failed.isNotEmpty) {
+      buffer.write(_red);
+      buffer.write(' -');
+      buffer.write(_failed.length);
+      buffer.write(_noColor);
+    }
+
+    buffer.write(': ');
+    buffer.write(color);
+
+    // Ensure the line fits within [_lineLength]. [buffer] includes the color
+    // escape sequences too. Because these sequences are not visible characters,
+    // we make sure they are not counted towards the limit.
+    var nonVisible = 1 + _green.length + _noColor.length + color.length +
+        (_failed.isEmpty ? 0 : _red.length + _noColor.length);
+    var length = buffer.length - nonVisible;
+    buffer.write(_truncate(message, _lineLength - length));
+    buffer.write(_noColor);
+
+    // Pad the rest of the line so that it looks erased.
+    length = buffer.length - nonVisible - _noColor.length;
+    buffer.write(' ' * (_lineLength - length));
+    stdout.write(buffer.toString());
+  }
+
+  /// Returns a representation of [duration] as `MM:SS`.
+  String _timeString(Duration duration) {
+    return "${duration.inMinutes.toString().padLeft(2, '0')}:"
+        "${(duration.inSeconds % 60).toString().padLeft(2, '0')}";
+  }
+
+  /// Truncates [text] to fit within [maxLength].
+  ///
+  /// This will try to truncate along word boundaries and preserve words both at
+  /// the beginning and the end of [text].
+  String _truncate(String text, int maxLength) {
+    // Return the full message if it fits.
+    if (text.length <= maxLength) return text;
+
+    // If we can fit the first and last three words, do so.
+    var words = text.split(' ');
+    if (words.length > 1) {
+      var i = words.length;
+      var length = words.first.length + 4;
+      do {
+        i--;
+        length += 1 + words[i].length;
+      } while (length <= maxLength && i > 0);
+      if (length > maxLength || i == 0) i++;
+      if (i < words.length - 4) {
+        // Require at least 3 words at the end.
+        var buffer = new StringBuffer();
+        buffer.write(words.first);
+        buffer.write(' ...');
+        for ( ; i < words.length; i++) {
+          buffer.write(' ');
+          buffer.write(words[i]);
+        }
+        return buffer.toString();
+      }
+    }
+
+    // Otherwise truncate to return the trailing text, but attempt to start at
+    // the beginning of a word.
+    var result = text.substring(text.length - maxLength + 4);
+    var firstSpace = result.indexOf(' ');
+    if (firstSpace > 0) {
+      result = result.substring(firstSpace);
+    }
+    return '...$result';
+  }
+
+  /// Returns a description of [liveTest].
+  ///
+  /// This differs from the test's own description in that it may also include
+  /// the suite's name.
+  String _description(LiveTest liveTest) {
+    if (_multipleSuites) return "${liveTest.suite.name}: ${liveTest.test.name}";
+    return liveTest.test.name;
+  }
+}