Make futures returned by AnalysisContext cancelable.

pkg/analyzer/test/cancelable_future_test.dart

+// Copyright (c) 2014, 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.cancelable_future;
+
+import 'reflective_tests.dart';
+import 'package:analyzer/src/cancelable_future.dart';
+import 'dart:async';
+import 'package:unittest/unittest.dart';
+import 'package:watcher/src/utils.dart';
+
+void main() {
+  groupSep = ' | ';
+  runReflectiveTests(CancelableCompleterTests);
+  runReflectiveTests(CancelableFutureTests);
+}
+
+@ReflectiveTestCase()
+class CancelableFutureTests {
+  Future test_defaultConstructor_returnValue() {
+    Object obj = new Object();
+    bool callbackInvoked = false;
+    new CancelableFuture(() => obj).then((result) {
+      expect(callbackInvoked, isFalse);
+      expect(result, same(obj));
+      callbackInvoked = true;
+    }, onError: (error) {
+      fail('Expected successful completion');
+    });
+    expect(callbackInvoked, isFalse);
+    return pumpEventQueue().then((_) {
+      expect(callbackInvoked, isTrue);
+    });
+  }
+
+  Future test_defaultConstructor_returnFuture() {
+    Object obj = new Object();
+    bool callbackInvoked = false;
+    new CancelableFuture(() => new Future(() => obj)).then((result) {
+      expect(callbackInvoked, isFalse);
+      expect(result, same(obj));
+      callbackInvoked = true;
+    }, onError: (error) {
+      fail('Expected successful completion');
+    });
+    expect(callbackInvoked, isFalse);
+    return pumpEventQueue().then((_) {
+      expect(callbackInvoked, isTrue);
+    });
+  }
+
+  Future test_defaultConstructor_throwException() {
+    Object obj = new Object();
+    bool callbackInvoked = false;
+    new CancelableFuture(() {
+      throw obj;
+    }).then((result) {
+      fail('Expected error completion');
+    }, onError: (error) {
+      expect(callbackInvoked, isFalse);
+      expect(error, same(obj));
+      callbackInvoked = true;
+    });
+    expect(callbackInvoked, isFalse);
+    return pumpEventQueue().then((_) {
+      expect(callbackInvoked, isTrue);
+    });
+  }
+
+  Future test_delayed_noCallback() {
+    DateTime start = new DateTime.now();
+    return new CancelableFuture.delayed(new Duration(seconds: 1)).then((result) {
+      DateTime end = new DateTime.now();
+      expect(result, isNull);
+      expect(end.difference(start).inMilliseconds > 900, isTrue);
+    });
+  }
+
+  Future test_delayed_withCallback() {
+    Object obj = new Object();
+    DateTime start = new DateTime.now();
+    return new CancelableFuture.delayed(new Duration(seconds: 1), () {
+      DateTime end = new DateTime.now();
+      expect(end.difference(start).inMilliseconds > 900, isTrue);
+      return obj;
+    }).then((result) {
+      expect(result, same(obj));
+    });
+  }
+
+  Future test_error() {
+    Object obj = new Object();
+    return new CancelableFuture.error(obj).then((result) {
+      fail('Expected error completion');
+    }, onError: (error) {
+      expect(error, same(obj));
+    });
+  }
+
+  Future test_microtask() {
+    Object obj = new Object();
+    bool callbackInvoked = false;
+    new CancelableFuture.microtask(() => obj).then((result) {
+      expect(callbackInvoked, isFalse);
+      expect(result, same(obj));
+      callbackInvoked = true;
+    }, onError: (error) {
+      fail('Expected successful completion');
+    });
+    expect(callbackInvoked, isFalse);
+    return pumpEventQueue().then((_) {
+      expect(callbackInvoked, isTrue);
+    });
+  }
+
+  Future test_sync() {
+    Object obj = new Object();
+    bool callbackInvoked = false;
+    new CancelableFuture.sync(() => obj).then((result) {
+      expect(callbackInvoked, isFalse);
+      expect(result, same(obj));
+      callbackInvoked = true;
+    }, onError: (error) {
+      fail('Expected successful completion');
+    });
+    expect(callbackInvoked, isFalse);
+    return pumpEventQueue().then((_) {
+      expect(callbackInvoked, isTrue);
+    });
+  }
+
+  Future test_value() {
+    Object obj = new Object();
+    return new CancelableFuture.value(obj).then((result) {
+      expect(result, same(obj));
+    }, onError: (error) {
+      fail('Expected successful completion');
+    });
+  }
+}
+
+@ReflectiveTestCase()
+class CancelableCompleterTests {
+  CancelableCompleter<Object> completer;
+  int cancelCount = 0;
+
+  void setUp() {
+    completer = new CancelableCompleter<Object>(() { cancelCount++; });
+  }
+
+  void test_initialState() {
+    expect(completer.isCompleted, isFalse);
+    expect(cancelCount, 0);
+  }
+
+  void test_complete_after_complete() {
+    // As with an ordinary Completer, calling complete() (or completeError)
+    // after calling complete() should throw an exception.
+    completer.complete();
+    expect(() { completer.complete(); }, throws);
+    expect(() { completer.completeError(new Object()); }, throws);
+  }
+
+  void test_complete_after_completeError() {
+    // As with an ordinary Completer, calling complete() (or completeError)
+    // after calling completeError() should throw an exception.
+    completer.completeError(new Object());
+    expect(() { completer.complete(); }, throws);
+    expect(() { completer.completeError(new Object()); }, throws);
+    // Now absorb the error that's in the completer's future.
+    completer.future.catchError((_) => null);
+  }
+
+  Future test_complete_before_chaining() {
+    Object obj = new Object();
+    completer.complete(obj);
+    expect(completer.isCompleted, isTrue);
+    bool callbackInvoked = false;
+    completer.future.then((result) {
+      expect(callbackInvoked, isFalse);
+      expect(result, same(obj));
+      callbackInvoked = true;
+    }, onError: (error) {
+      fail('Expected successful completion');
+    });
+    // The callback should be deferred to a microtask.
+    expect(callbackInvoked, isFalse);
+    expect(completer.isCompleted, isTrue);
+    return pumpEventQueue().then((_) {
+      expect(callbackInvoked, isTrue);
+      expect(completer.isCompleted, isTrue);
+      expect(cancelCount, 0);
+    });
+  }
+
+  Future test_completeError_before_chaining() {
+    Object obj = new Object();
+    completer.completeError(obj);
+    expect(completer.isCompleted, isTrue);
+    bool callbackInvoked = false;
+    completer.future.then((_) {
+      fail('Expected error completion');
+    }, onError: (error) {
+      expect(callbackInvoked, isFalse);
+      expect(error, same(obj));
+      callbackInvoked = true;
+    });
+    // The callback should be deferred to a microtask.
+    expect(callbackInvoked, isFalse);
+    expect(completer.isCompleted, isTrue);
+    return pumpEventQueue().then((_) {
+      expect(callbackInvoked, isTrue);
+      expect(completer.isCompleted, isTrue);
+      expect(cancelCount, 0);
+    });
+  }
+
+  Future test_complete_after_chaining() {
+    Object obj = new Object();
+    bool callbackInvoked = false;
+    completer.future.then((result) {
+      expect(callbackInvoked, isFalse);
+      expect(result, same(obj));
+      callbackInvoked = true;
+    }, onError: (error) {
+      fail('Expected successful completion');
+    });
+    expect(completer.isCompleted, isFalse);
+    // Running the event loop should have no effect since the completer hasn't
+    // been completed yet.
+    return pumpEventQueue().then((_) {
+      completer.complete(obj);
+      expect(completer.isCompleted, isTrue);
+      // The callback should be deferred to a microtask.
+      expect(callbackInvoked, isFalse);
+    }).then((_) => pumpEventQueue()).then((_) {
+      expect(callbackInvoked, isTrue);
+      expect(completer.isCompleted, isTrue);
+      expect(cancelCount, 0);
+    });
+  }
+
+  Future test_completeError_after_chaining() {
+    Object obj = new Object();
+    bool callbackInvoked = false;
+    completer.future.then((_) {
+      fail('Expected error completion');
+    }, onError: (error) {
+      expect(callbackInvoked, isFalse);
+      expect(error, same(obj));
+      callbackInvoked = true;
+    });
+    expect(completer.isCompleted, isFalse);
+    // Running the event loop should have no effect since the completer hasn't
+    // been completed yet.
+    return pumpEventQueue().then((_) {
+      completer.completeError(obj);
+      expect(completer.isCompleted, isTrue);
+      // The callback should be deferred to a microtask.
+      expect(callbackInvoked, isFalse);
+    }).then((_) => pumpEventQueue()).then((_) {
+      expect(callbackInvoked, isTrue);
+      expect(completer.isCompleted, isTrue);
+      expect(cancelCount, 0);
+    });
+  }
+
+  Future test_cancel_before_chaining() {
+    completer.future.cancel();
+    // The cancel callback should have been invoked immediately.
+    expect(cancelCount, 1);
+    // But the completer should remain in the "not completed" state.
+    expect(completer.isCompleted, isFalse);
+    bool callbackInvoked = false;
+    completer.future.then((_) {
+      fail('Expected error completion');
+    }, onError: (error) {
+      expect(callbackInvoked, isFalse);
+      expect(error, new isInstanceOf<FutureCanceledError>());
+      callbackInvoked = true;
+    });
+    // The callback should be deferred to a microtask.
+    expect(callbackInvoked, isFalse);
+    expect(completer.isCompleted, isFalse);
+    return pumpEventQueue().then((_) {
+      expect(callbackInvoked, isTrue);
+      expect(completer.isCompleted, isFalse);
+      expect(cancelCount, 1);
+    });
+  }
+
+  Future test_cancel_after_chaining() {
+    bool callbackInvoked = false;
+    completer.future.then((_) {
+      fail('Expected error completion');
+    }, onError: (error) {
+      expect(callbackInvoked, isFalse);
+      expect(error, new isInstanceOf<FutureCanceledError>());
+      callbackInvoked = true;
+    });
+    expect(cancelCount, 0);
+    completer.future.cancel();
+    // The cancel callback should have been invoked immediately.
+    expect(cancelCount, 1);
+    // But the completer should remain in the "not completed" state.
+    expect(completer.isCompleted, isFalse);
+    // The callback should be deferred to a microtask.
+    expect(callbackInvoked, isFalse);
+    return pumpEventQueue().then((_) {
+      expect(callbackInvoked, isTrue);
+      expect(completer.isCompleted, isFalse);
+      expect(cancelCount, 1);
+    });
+  }
+
+  Future test_cancel_after_complete() {
+    Object obj = new Object();
+    completer.complete(obj);
+    completer.future.cancel();
+    // The cancel callback should not have been invoked, because it was too
+    // late to cancel.
+    expect(cancelCount, 0);
+    // Make sure the future still completes with the object.
+    return completer.future.then((result) {
+      expect(result, same(obj));
+      // And make sure nothing else happens.
+    }).then((_) => pumpEventQueue()).then((_) {
+      expect(completer.isCompleted, isTrue);
+      expect(cancelCount, 0);
+    });
+  }
+
+  Future test_complete_after_cancel() {
+    completer.future.cancel();
+    // The cancel callback should have been invoked immediately.
+    expect(cancelCount, 1);
+    // Completing should have no effect other than to set the isCompleted
+    // flag.
+    expect(completer.isCompleted, isFalse);
+    Object obj = new Object();
+    completer.complete(obj);
+    expect(completer.isCompleted, isTrue);
+    // Make sure the future still completer with error.
+    return completer.future.then((_) {
+      fail('Expected error completion');
+    }, onError: (error) {
+      expect(error, new isInstanceOf<FutureCanceledError>());
+      // And make sure nothing else happens.
+    }).then((_) => pumpEventQueue()).then((_) {
+      expect(completer.isCompleted, isTrue);
+      expect(cancelCount, 1);
+    });
+  }
+
+  Future test_completeError_after_cancel() {
+    completer.future.cancel();
+    // The cancel callback should have been invoked immediately.
+    expect(cancelCount, 1);
+    // Completing should have no effect other than to set the isCompleted
+    // flag.
+    expect(completer.isCompleted, isFalse);
+    Object obj = new Object();
+    completer.completeError(obj);
+    expect(completer.isCompleted, isTrue);
+    // Make sure the future still completes with error.
+    return completer.future.then((_) {
+      fail('Expected error completion');
+    }, onError: (error) {
+      expect(error, new isInstanceOf<FutureCanceledError>());
+      // And make sure nothing else happens.
+    }).then((_) => pumpEventQueue()).then((_) {
+      expect(completer.isCompleted, isTrue);
+      expect(cancelCount, 1);
+    });
+  }
+
+  Future test_cancel_after_cancel() {
+    // It is permissible to cancel multiple times, but only the first
+    // cancellation has any effect.
+    expect(cancelCount, 0);
+    completer.future.cancel();
+    expect(cancelCount, 1);
+    completer.future.cancel();
+    expect(cancelCount, 1);
+    // Make sure the future still completes with error.
+    return completer.future.then((_) {
+      fail('Expected error completion');
+    }, onError: (error) {
+      expect(error, new isInstanceOf<FutureCanceledError>());
+      // And make sure nothing else happens.
+    }).then((_) => pumpEventQueue()).then((_) {
+      expect(completer.isCompleted, isFalse);
+      expect(cancelCount, 1);
+    });
+  }
+}