Add Declarer and Group classes.

lib/src/declarer.dart

+// 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.declarer;
+
+import 'dart:collection';
+
+import 'group.dart';
+import 'invoker.dart';
+import 'test.dart';
+
+/// A class that manages the state of tests as they're declared.
+///
+/// This is in charge of tracking the current group, set-up, and tear-down
+/// functions. It produces a list of runnable [tests].
+class Declarer {
+  /// The current group.
+  var _group = new Group.root();
+
+  /// The list of tests that have been defined.
+  List<Test> get tests => new UnmodifiableListView<Test>(_tests);
+  final _tests = new List<Test>();
+
+  Declarer();
+
+  /// Defines a test case with the given description and body.
+  ///
+  /// The description will be added to the descriptions of any surrounding
+  /// [group]s.
+  void test(String description, body()) {
+    // TODO(nweiz): Once tests have begun running, throw an error if [test] is
+    // called.
+    var prefix = _group.description;
+    if (prefix != null) description = "$prefix $description";
+
+    var group = _group;
+    _tests.add(new LocalTest(description, () {
+      // TODO(nweiz): It might be useful to throw an error here if a test starts
+      // running while other tests from the same declarer are also running,
+      // since they might share closurized state.
+      return group.runSetUp().then((_) => body());
+    }, tearDown: group.runTearDown));
+  }
+
+  /// Creates a group of tests.
+  ///
+  /// A group's description is included in the descriptions of any tests or
+  /// sub-groups it contains. [setUp] and [tearDown] are also scoped to the
+  /// containing group.
+  void group(String description, void body()) {
+    var oldGroup = _group;
+    _group = new Group(oldGroup, description);
+    try {
+      body();
+    } finally {
+      _group = oldGroup;
+    }
+  }
+
+  /// Registers a function to be run before tests.
+  ///
+  /// This function will be called before each test is run. [callback] may be
+  /// asynchronous; if so, it must return a [Future].
+  ///
+  /// If this is called within a [group], it applies only to tests in that
+  /// group. [callback] will be run after any set-up callbacks in parent groups
+  /// or at the top level.
+  void setUp(callback()) {
+    if (_group.setUp != null) {
+      throw new StateError("setUp() may not be called multiple times for the "
+          "same group.");
+    }
+
+    _group.setUp = callback;
+  }
+
+  /// Registers a function to be run after tests.
+  ///
+  /// This function will be called after each test is run. [callback] may be
+  /// asynchronous; if so, it must return a [Future].
+  ///
+  /// If this is called within a [group], it applies only to tests in that
+  /// group. [callback] will be run before any tear-down callbacks in parent
+  /// groups or at the top level.
+  void tearDown(callback()) {
+    if (_group.tearDown != null) {
+      throw new StateError("tearDown() may not be called multiple times for "
+          "the same group.");
+    }
+
+    _group.tearDown = callback;
+  }
+}