Add tests for `FutureOr<T>`.

tests/lib/async/future_or_strong_test.dart

+// 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.
+
+// In strong mode, `FutureOr` should be equivalent to the union of `Future<T>`
+// and `T`.
+
+import 'dart:async';
+import 'package:expect/expect.dart';
+
+void foo(FutureOr x) {}  // Equivalent to `void bar(Object x) {}`.

[Lasse Reichstein Nielsen, 2016/12/08 18:20:29]

So this is a strong-mode only test?

[floitsch, 2016/12/08 18:41:55]

Yes. As hinted by the name and the description on the top of the file.

+FutureOr bar() => 499;  // Equivalent to `Object foo() => null`.

[Lasse Reichstein Nielsen, 2016/12/08 18:20:29]

=> 499?

[floitsch, 2016/12/08 18:41:55]

Done.

+
+void foo2(FutureOr<String> x) {}
+FutureOr<int> bar2() => 499;
+
+void foo3(String x) {}
+int bar3() => 499;
+
+typedef void FunTakes<T>(T x);
+typedef T FunReturns<T>();
+
+main() {
+  Expect.isTrue(499 is FutureOr);  // Same as `is Object`.
+  Expect.isTrue(499 is FutureOr<int>);
+  Expect.isFalse(499 is FutureOr<String>);
+
+  Expect.isTrue(new Future.value(499) is FutureOr);  // Same as `is Object`.
+  Expect.isTrue(new Future.value(499) is FutureOr<int>);
+  Expect.isFalse(new Future.value(499) is FutureOr<String>);
+
+  // A function that takes Object takes everything.
+  Expect.isTrue(foo is FunTakes<dynamic>);
+  Expect.isTrue(foo is FunTakes<Object>);
+  Expect.isTrue(foo is FunTakes<int>);
+  Expect.isTrue(foo is FunTakes<String>);
+  Expect.isTrue(foo is FunTakes<Future<int>>);
+  Expect.isTrue(foo is FunTakes<Future<String>>);
+  Expect.isTrue(foo is FunTakes<FutureOr<Object>>);
+  Expect.isTrue(foo is FunTakes<FutureOr<int>>);
+  Expect.isTrue(foo is FunTakes<FutureOr<String>>);
+  Expect.isTrue(foo is FunTakes<FutureOr<FutureOr<Object>>>);
+  Expect.isTrue(foo is FunTakes<FutureOr<FutureOr<int>>>);
+  Expect.isTrue(foo is FunTakes<FutureOr<FutureOr<String>>>);
+
+  // Is check treats `dynamic` special in function types.

[Lasse Reichstein Nielsen, 2016/12/08 18:20:29]

special -> specially
Sentence is hard to read. Also, it doesn't treat dynamic specially as a return
type, only as an argument type.

[floitsch, 2016/12/08 18:41:55]

Done.

+  Expect.isTrue(bar is FunReturns<dynamic>);
+
+  Expect.isTrue(bar is FunReturns<Object>);
+  Expect.isFalse(bar is FunReturns<int>);
+  Expect.isFalse(bar is FunReturns<String>);
+  Expect.isFalse(bar is FunReturns<Future<int>>);
+  Expect.isFalse(bar is FunReturns<Future<String>>);
+  Expect.isTrue(bar is FunReturns<FutureOr<Object>>);
+  Expect.isFalse(bar is FunReturns<FutureOr<int>>);
+  Expect.isFalse(bar is FunReturns<FutureOr<String>>);
+  Expect.isTrue(bar is FunReturns<FutureOr<FutureOr<Object>>>);
+  Expect.isFalse(bar is FunReturns<FutureOr<FutureOr<int>>>);
+  Expect.isFalse(bar is FunReturns<FutureOr<FutureOr<String>>>);
+
+  // Is check treats `dynamic` special in function types.
+  Expect.isTrue(foo2 is FunTakes<dynamic>);
+
+  Expect.isTrue(foo2 is FunTakes<Object>);

[Lasse Reichstein Nielsen, 2016/12/08 18:20:29]

isFalse. foo2 takes String or Future<String>, but not Object.

[floitsch, 2016/12/08 18:41:55]

Done.

+  Expect.isFalse(foo2 is FunTakes<int>);
+  Expect.isTrue(foo2 is FunTakes<String>);
+  Expect.isFalse(foo2 is FunTakes<Future<int>>);
+  Expect.isTrue(foo2 is FunTakes<Future<String>>);
+  Expect.isFalse(foo2 is FunTakes<FutureOr<Object>>);
+  Expect.isFalse(foo2 is FunTakes<FutureOr<int>>);
+  Expect.isTrue(foo2 is FunTakes<FutureOr<String>>);
+  Expect.isFalse(foo2 is FunTakes<FutureOr<FutureOr<Object>>>);
+  Expect.isFalse(foo2 is FunTakes<FutureOr<FutureOr<int>>>);
+  Expect.isFalse(foo2 is FunTakes<FutureOr<FutureOr<String>>>);
+
+  // Is check treats `dynamic` special in function types.
+  Expect.isTrue(bar2 is FunReturns<dynamic>);
+
+  Expect.isTrue(bar2 is FunReturns<Object>);
+  Expect.isFalse(bar2 is FunReturns<int>);
+  Expect.isFalse(bar2 is FunReturns<String>);
+  Expect.isFalse(bar2 is FunReturns<Future<int>>);
+  Expect.isFalse(bar2 is FunReturns<Future<String>>);
+  Expect.isTrue(bar2 is FunReturns<FutureOr<Object>>);
+  Expect.isTrue(bar2 is FunReturns<FutureOr<int>>);
+  Expect.isFalse(bar2 is FunReturns<FutureOr<String>>);
+  Expect.isTrue(bar2 is FunReturns<FutureOr<FutureOr<Object>>>);
+  Expect.isTrue(bar2 is FunReturns<FutureOr<FutureOr<int>>>);
+  Expect.isFalse(bar2 is FunReturns<FutureOr<FutureOr<String>>>);
+
+  // Is check treats `dynamic` special in function types.
+  Expect.isTrue(foo3 is FunTakes<dynamic>);
+
+  Expect.isFalse(foo3 is FunTakes<Object>);
+  Expect.isFalse(foo3 is FunTakes<int>);
+  Expect.isTrue(foo3 is FunTakes<String>);
+  Expect.isFalse(foo3 is FunTakes<Future<int>>);
+  Expect.isFalse(foo3 is FunTakes<Future<String>>);
+  Expect.isFalse(foo3 is FunTakes<FutureOr<Object>>);
+  Expect.isFalse(foo3 is FunTakes<FutureOr<int>>);
+  Expect.isFalse(foo3 is FunTakes<FutureOr<String>>);
+  Expect.isFalse(foo3 is FunTakes<FutureOr<FutureOr<Object>>>);
+  Expect.isFalse(foo3 is FunTakes<FutureOr<FutureOr<int>>>);
+  Expect.isFalse(foo3 is FunTakes<FutureOr<FutureOr<String>>>);
+
+  // Is check treats `dynamic` special in function types.
+  Expect.isTrue(bar3 is FunReturns<dynamic>);
+
+  Expect.isTrue(bar3 is FunReturns<Object>);
+  Expect.isTrue(bar3 is FunReturns<int>);
+  Expect.isFalse(bar3 is FunReturns<String>);
+  Expect.isFalse(bar3 is FunReturns<Future<int>>);
+  Expect.isFalse(bar3 is FunReturns<Future<String>>);
+  Expect.isTrue(bar3 is FunReturns<FutureOr<Object>>);
+  Expect.isTrue(bar3 is FunReturns<FutureOr<int>>);
+  Expect.isFalse(bar3 is FunReturns<FutureOr<String>>);
+  Expect.isTrue(bar3 is FunReturns<FutureOr<FutureOr<Object>>>);
+  Expect.isTrue(bar3 is FunReturns<FutureOr<FutureOr<int>>>);
+  Expect.isFalse(bar3 is FunReturns<FutureOr<FutureOr<String>>>);
+}