Add Dart_IsFuture. To be used in Dartium implementation of Promises.

runtime/vm/dart_api_impl_test.cc

Index: runtime/vm/dart_api_impl_test.cc
diff --git a/runtime/vm/dart_api_impl_test.cc b/runtime/vm/dart_api_impl_test.cc
index 4b0b5d51fccaf47a031352c86564b57888497486..ab8d188203cd1e27d3e68250cee5d6e52f6d697d 100644
--- a/runtime/vm/dart_api_impl_test.cc
+++ b/runtime/vm/dart_api_impl_test.cc
@@ -1384,6 +1384,24 @@ TEST_CASE(MapAccess) {
 }
 
 
+TEST_CASE(IsFuture) {
+  const char* kScriptChars =
+      "import 'dart:async';"
+      "Future testMain() {"
+      "  return new Completer().future;"
+      "}";
+  Dart_Handle result;
+
+  // Create a test library and Load up a test script in it.
+  Dart_Handle lib = TestCase::LoadTestScript(kScriptChars, NULL);
+
+  // Invoke a function which returns an object of type Map.
+  result = Dart_Invoke(lib, NewString("testMain"), 0, NULL);
+  EXPECT_VALID(result);
+  EXPECT(Dart_IsFuture(result));

[siva, 2014/09/19 17:38:36]

You probably also want a negative test:

Dart_Handle zero = Dart_NewInteger(0);
EXPECT(!Dart_IsFuture(zero));
Dart_Handle str = NewString("I am not a Future");
EXPECT(!Dart_IsFuture(str));

[rmacnak, 2014/09/19 21:32:03]

Added

+}
+
+
 TEST_CASE(TypedDataViewListGetAsBytes) {
   const int kSize = 1000;