Add a scheduled test library.

pkg/scheduled_test/test/metatest.dart

Index: pkg/scheduled_test/test/metatest.dart
diff --git a/pkg/scheduled_test/test/metatest.dart b/pkg/scheduled_test/test/metatest.dart
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+// Copyright (c) 2013, 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.
+
+/// A test library for testing test libraries? We must go deeper.
+///
+/// Since unit testing code tends to use a lot of global state, it can be tough
+/// to test. This library manages it by running each test case in a child
+/// isolate, then reporting the results back to the parent isolate.
+library metatest;
+
+import 'dart:async';
+import 'dart:isolate';
+
+import '../../../pkg/path/lib/path.dart' as path;
+import 'package:scheduled_test/src/utils.dart';
+import 'package:unittest/unittest.dart';
+
+/// Declares a test with the given [description] and [body]. [body] corresponds
+/// to the `main` method of a test file, and will be run in an isolate. By
+/// default, this expects that all tests defined in [body] pass, but if
+/// [passing] is passed, only tests listed there are expected to pass.
+void expectTestsPass(String description, void body(), {List<String> passing}) {
+  _setUpTest(description, body, (results) {
+    if (_hasError(results)) {
+      throw 'Expected all tests to pass, but got error(s):\n'
+          '${_summarizeTests(results)}';
+    } else if (passing == null) {
+      if (results['failed'] != 0) {
+        throw 'Expected all tests to pass, but some failed:\n'
+            '${_summarizeTests(results)}';
+      }
+    } else {
+      var shouldPass = new Set.from(passing);
+      var didPass = new Set.from(results['results']
+          .where((t) => t['result'] == 'pass')
+          .map((t) => t['description']));
+
+      if (!shouldPass.containsAll(didPass) ||
+          !didPass.containsAll(shouldPass)) {
+        String stringify(Set<String> tests) =>
+          '{${tests.map((t) => '"$t"').join(', ')}}';
+
+        fail('Expected exactly ${stringify(shouldPass)} to pass, but '
+            '${stringify(didPass)} passed.\n'
+            '${_summarizeTests(results)}');
+      }
+    }
+  });
+}
+
+/// Declares a test with the given [description] and [body]. [body] corresponds
+/// to the `main` method of a test file, and will be run in an isolate. Expects
+/// all tests defined by [body] to fail.
+void expectTestsFail(String description, void body()) {
+  _setUpTest(description, body, (results) {
+    if (_hasError(results)) {
+      throw 'Expected all tests to fail, but got error(s):\n'
+          '${_summarizeTests(results)}';
+    } else if (results['passed'] != 0) {
+      throw 'Expected all tests to fail, but some passed:\n'
+          '${_summarizeTests(results)}';
+    }
+  });
+}
+
+/// Sets up a test with the given [description] and [body]. After the test runs,
+/// calls [validate] with the result map.
+void _setUpTest(String description, void body(), void validate(Map)) {
+  _inChildIsolate.then((inIsolate) {
+    if (inIsolate) {
+      _ensureInitialized();
+      if (_testToRun == description) body();
+    } else {
+      test(description, () {
+        expect(_runInIsolate(description).then(validate), completes);
+      });
+    }
+  });
+}
+
+/// The description of the test to run in the child isolate. `null` in the
+/// parent isolate. Not set until [_inChildIsolate] completes.
+String _testToRun;
+
+/// The port with which the child isolate should communicate with the parent
+/// isolate. `null` in the parent isolate. Not set until [_inChildIsolate]
+/// completes.
+SendPort _replyTo;
+
+/// The cached [Future] for [_inChildIsolate].
+Future<bool> _inChildIsolateFuture;
+
+/// Returns whether or not we're running in a child isolate that's supposed to
+/// run a test.
+Future<bool> get _inChildIsolate {
+  if (_inChildIsolateFuture != null) return _inChildIsolateFuture;
+
+  var completer = new Completer();
+  port.receive((message, replyTo) {
+    _testToRun = message;
+    _replyTo = replyTo;
+    port.close();
+    completer.complete(true);
+  });
+
+  // TODO(nweiz): don't use a timeout here once issue 8416 is fixed.
+  _inChildIsolateFuture = timeout(completer.future, 500, () {
+    port.close();
+    return false;
+  });
+  return _inChildIsolateFuture;
+}
+
+/// Runs the test described by [description] in its own isolate. Returns a map
+/// describing the results of that test run.
+Future<Map> _runInIsolate(String description) {
+  var future = spawnUri(path.join(path.current, new Options().script))
+      .call(description);
+  // TODO(nweiz): Remove this timeout once issue 8417 is fixed and we can
+  // capture top-level exceptions.
+  return timeout(future, 30 * 1000, () {
+    throw 'Timed out waiting for test to complete.';
+  });
+}
+
+/// Returns whether [results] (a test result map) describes a test run in which
+/// an error occurred.
+bool _hasError(Map results) {
+  return results['errors'] > 0 || results['uncaughtError'] != null ||
+    (results['passed'] == 0 && results['failed'] == 0);
+}
+
+/// Returns a string description of the test run descibed by [results].
+String _summarizeTests(Map results) {
+  var buffer = new StringBuffer();
+  for (var t in results["results"]) {
+    buffer.add("${t['result'].toUpperCase()}: ${t['description']}\n");
+    if (t['message'] != '') buffer.add("${_indent(t['message'])}\n");
+    if (t['stackTrace'] != null && t['stackTrace'] != '') {
+      buffer.add("${_indent(t['stackTrace'])}\n");
+    }
+  }
+
+  buffer.add("\n");
+
+  var success = false;
+  if (results['passed'] == 0 && results['failed'] == 0 &&
+      results['errors'] == 0 && results['uncaughtError'] == null) {
+    buffer.add('No tests found.');
+    // This is considered a failure too.
+  } else if (results['failed'] == 0 && results['errors'] == 0 &&
+      results['uncaughtError'] == null) {
+    buffer.add('All ${results['passed']} tests passed.');
+    success = true;
+  } else {
+    if (results['uncaughtError'] != null) {
+      buffer.add('Top-level uncaught error: ${results['uncaughtError']}');
+    }
+    buffer.add('${results['passed']} PASSED, ${results['failed']} FAILED, '
+        '${results['errors']} ERRORS');
+  }
+  return prefixLines(buffer.toString());
+}
+
+/// Indents each line of [str] by two spaces.
+String _indent(String str) {
+  // TODO(nweiz): Use this simpler code once issue 2980 is fixed.
+  // return str.replaceAll(new RegExp("^", multiLine: true), "  ");
+
+  return Strings.join(str.split("\n").map((line) => "  $line"), "\n");
+}
+
+/// Ensure that the metatest configuration is loaded.
+void _ensureInitialized() {
+  if (config is! _MetaConfiguration) configure(new _MetaConfiguration());
+}
+
+/// Special test configuration for use within the child isolates. This hides all
+/// output and reports data back to the parent isolate.
+class _MetaConfiguration extends Configuration {
+  final name = "MetaConfiguration";
+
+  void logTestCaseMesssage(TestCase testCase, String message) {}
+
+  void onSummary(int passed, int failed, int errors, List<TestCase> results,
+      String uncaughtError) {
+    _replyTo.send({
+      "passed": passed,
+      "failed": failed,
+      "errors": errors,
+      "uncaughtError": uncaughtError,
+      "results": results.map((testCase) => {
+        "description": testCase.description,
+        "message": testCase.message,
+        "result": testCase.result,
+        "stackTrace": testCase.stackTrace
+      }).toList()
+    });
+  }
+
+  void onInit() {}
+  void onDone(bool success) {}
+}