patch from issue 9360020

tests/corelib/src/FutureTest.dart

+// Copyright (c) 2012, 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.
+
+testImmediate() {
+  final future = new Future<String>.immediate("42");
+  Expect.isTrue(future.isComplete);
+  var value = null;
+  future.then((x) => value = x);
+  Expect.equals("42", value);
+}
+
+testTransformSuccess() {
+  final completer = new Completer<String>();
+  final transformedFuture = completer.future.transform((x) => "** $x **");
+  Expect.isFalse(transformedFuture.isComplete);
+  completer.complete("42");
+  Expect.equals("** 42 **", transformedFuture.value);
+}
+
+testTransformFutureFails() {
+  final completer = new Completer<String>();
+  final error = new Exception("Oh no!");
+  final transformedFuture = completer.future.transform((x) {
+    Expect.fail("transformer shouldn't be called");
+  });
+  Expect.isFalse(transformedFuture.isComplete);
+  completer.completeException(error);
+  Expect.equals(error, transformedFuture.exception);
+}
+
+testTransformTransformerFails() {
+  final completer = new Completer<String>();
+  final error = new Exception("Oh no!");
+  final transformedFuture = completer.future.transform((x) { throw error; });
+  Expect.isFalse(transformedFuture.isComplete);
+  completer.complete("42");
+  Expect.equals(error, transformedFuture.exception);
+}
+
+testChainSuccess() {
+  final completerA = new Completer<String>();
+  final completerB = new Completer<String>();
+  final chainedFuture = completerA.future.chain((x) {
+    Expect.equals("42", x);
+    return completerB.future;
+  });
+  Expect.isFalse(chainedFuture.isComplete);
+  completerA.complete("42");
+  Expect.isFalse(chainedFuture.isComplete);
+  completerB.complete("43");
+  Expect.equals("43", chainedFuture.value);
+}
+
+testChainFirstFutureFails() {
+  final completerA = new Completer<String>();
+  final error = new Exception("Oh no!");
+  final chainedFuture = completerA.future.chain((x) {
+    Expect.fail("transformer shouldn't be called");
+  });
+  Expect.isFalse(chainedFuture.isComplete);
+  completerA.completeException(error);
+  Expect.equals(error, chainedFuture.exception);
+}
+
+testChainTransformerFails() {
+  final completerA = new Completer<String>();
+  final error = new Exception("Oh no!");
+  final chainedFuture = completerA.future.chain((x) {
+    Expect.equals("42", x);
+    throw error;
+  });
+  Expect.isFalse(chainedFuture.isComplete);
+  completerA.complete("42");
+  Expect.equals(error, chainedFuture.exception);
+}
+
+testChainSecondFutureFails() {
+  final completerA = new Completer<String>();
+  final completerB = new Completer<String>();
+  final error = new Exception("Oh no!");
+  final chainedFuture = completerA.future.chain((x) {
+    Expect.equals("42", x);
+    return completerB.future;
+  });
+  Expect.isFalse(chainedFuture.isComplete);
+  completerA.complete("42");
+  Expect.isFalse(chainedFuture.isComplete);
+  completerB.completeException(error);
+  Expect.equals(error, chainedFuture.exception);
+}
+
+main() {
+  testImmediate();
+  testTransformSuccess();
+  testTransformFutureFails();
+  testTransformTransformerFails();
+  testChainSuccess();
+  testChainFirstFutureFails();
+  testChainTransformerFails();
+  testChainSecondFutureFails();
+}