Add a LiveSuite class.

lib/src/runner/live_suite.dart

Index: lib/src/runner/live_suite.dart
diff --git a/lib/src/runner/live_suite.dart b/lib/src/runner/live_suite.dart
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+// 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.
+
+import 'dart:async';
+
+import 'package:collection/collection.dart';
+
+import '../backend/live_test.dart';
+import 'runner_suite.dart';
+
+/// A view of the execution of a test suite.
+///
+/// This is distinct from [Suite] because it represents the progress of running
+/// a suite rather than the suite's contents. It provides events and collections
+/// that give the caller a view into the suite's current state.
+abstract class LiveSuite {
+  /// The suite that's being run.
+  RunnerSuite get suite;
+
+  /// Whether the suite has completed.
+  ///
+  /// Note that even if this returns `true`, the suite may still be running code
+  /// asynchronously. A suite is considered complete once all of its tests are
+  /// complete, but it's possible for a test to continue running even after it's
+  /// been marked complete—see [LiveTest.isComplete] for details.
+  ///
+  /// The [isClosed] getter can be used to determine whether the suite and its
+  /// tests are guaranteed to emit no more events.
+  bool get isComplete;
+
+  /// A [Future] that completes once the suite is complete.
+  ///
+  /// Note that even once this completes, the suite may still be running code
+  /// asynchronously. A suite is considered complete once all of its tests are
+  /// complete, but it's possible for a test to continue running even after it's
+  /// been marked complete—see [LiveTest.isComplete] for details.
+  ///
+  /// The [onComplete] future can be used to determine when the suite and its
+  /// tests are guaranteed to emit no more events.
+  Future get onComplete;
+
+  /// Whether the suite has been closed.
+  ///
+  /// If this is `true`, no code is running for the suite or any of its tests.
+  /// At this point, the caller can be sure that the suites' tests are all in
+  /// fixed states that will not change in the future.
+  bool get isClosed;
+
+  /// A [Future] that completes when the suite has been closed.
+  ///
+  /// Once this completes, no code is running for the suite or any of its tests.
+  /// At this point, the caller can be sure that the suites' tests are all in
+  /// fixed states that will not change in the future.
+  Future get onClose;
+
+  /// All the currently-known tests in this suite that have run or are running.
+  ///
+  /// This is guaranteed to contain the same tests as the union of [passed],
+  /// [skipped], [failed], and [active].
+  Set<LiveTest> get liveTests {
+    var sets = [passed, skipped, failed];
+    if (active != null) sets.add(new Set.from([active]));
+    return new GroupSet.from(sets);
+  }
+
+  /// A stream that emits each [LiveTest] in this suite as it's about to start
+  /// running.
+  ///
+  /// This is guaranteed to fire before [LiveTest.onStateChange] first fires. It
+  /// will close once all tests the user has selected are run.
+  Stream<LiveTest> get onTestStarted;
+
+  /// The set of tests in this suite that have completed and been marked as
+  /// passing.
+  Set<LiveTest> get passed;
+
+  /// The set of tests in this suite that have completed and been marked as
+  /// skipped.
+  Set<LiveTest> get skipped;
+
+  /// The set of tests in this suite that have completed and been marked as
+  /// failing or error.
+  Set<LiveTest> get failed;
+
+  /// The currently running test in this suite, or `null` if no test is running.
+  LiveTest get active;
+}