Run test tearDowns and clean up temporary directories when a signal is caught.

lib/src/backend/live_test.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 test.backend.live_test;
 
 import 'dart:async';
 
 import 'state.dart';
 import 'suite.dart';
@@ skipping 93 matching lines @@
   /// This returns the same [Future] as [onComplete]. It may not be called more
   /// than once.
   Future run();
 
   /// Signals that this test should stop emitting events and release any
   /// resources it may have allocated.
   ///
   /// Once [close] is called, [onComplete] will complete if it hasn't already
   /// and [onStateChange] and [onError] will close immediately. This means that,
   /// if the test was running at the time [close] is called, it will never emit
-  /// a [Status.complete] state-change event.
+  /// a [Status.complete] state-change event. Once a test is closed, [expect]
+  /// and [expectAsync] will throw a [ClosedException] to help the test
+  /// terminate as quickly as possible.
   ///
   /// This doesn't automatically happen after the test completes because there
   /// may be more asynchronous work going on in the background that could
   /// produce new errors.
+  ///
+  /// Returns a [Future] that completes once all resources are released *and*
+  /// the test has completed. This allows the caller to wait until the test's
+  /// tear-down logic has run.
   Future close();
 }