Add an async descriptor to scheduled_test.

pkg/scheduled_test/test/descriptor_test.dart

Index: pkg/scheduled_test/test/descriptor_test.dart
diff --git a/pkg/scheduled_test/test/descriptor_test.dart b/pkg/scheduled_test/test/descriptor_test.dart
index 2b71e8a7bbacca3ec9d1cafd9d12a19eeda42bd8..1a28c0c69e4101e2cde0de2fe6cd73571f120ee2 100644
--- a/pkg/scheduled_test/test/descriptor_test.dart
+++ b/pkg/scheduled_test/test/descriptor_test.dart
@@ -12,6 +12,7 @@ import 'package:scheduled_test/descriptor.dart' as d;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import 'metatest.dart';
+import 'utils.dart';
 
 String sandbox;
 
@@ -861,6 +862,132 @@ void main() {
       expect(d.dir('dir').describe(), equals('dir'));
     });
   });
+
+  expectTestsPass("async().create() forwards to file().create", () {
+    test('test', () {
+      scheduleSandbox();
+
+      d.async(pumpEventQueue().then((_) {
+        return d.file('name.txt', 'contents');
+      })).create();
+
+      d.file('name.txt', 'contents').validate();
+    });
+  });
+
+  expectTestsPass("async().create() forwards to directory().create", () {
+    test('test', () {
+      scheduleSandbox();
+
+      d.async(pumpEventQueue().then((_) {
+        return d.dir('dir', [
+          d.file('file1.txt', 'contents1'),
+          d.file('file2.txt', 'contents2')
+        ]);
+      })).create();
+
+      d.dir('dir', [
+        d.file('file1.txt', 'contents1'),
+        d.file('file2.txt', 'contents2')
+      ]).validate();
+    });
+  });
+
+  expectTestsPass("async().validate() forwards to file().validate", () {
+    test('test', () {
+      scheduleSandbox();
+
+      d.file('name.txt', 'contents').create();
+
+      d.async(pumpEventQueue().then((_) {
+        return d.file('name.txt', 'contents');
+      })).validate();
+    });
+  });
+
+  expectTestsPass("async().validate() fails if file().validate fails", () {
+    var errors;
+    test('test 1', () {
+      scheduleSandbox();
+
+      currentSchedule.onException.schedule(() {
+        errors = currentSchedule.errors;
+      });
+
+      d.async(pumpEventQueue().then((_) {
+        return d.file('name.txt', 'contents');
+      })).validate();
+    });
+
+    test('test 2', () {
+      expect(errors, everyElement(new isInstanceOf<ScheduleError>()));
+      expect(errors.length, equals(1));
+      expect(errors.first.error,
+          matches(r"^File not found: '[^']+[\\/]name\.txt'\.$"));
+    });
+  }, passing: ['test 2']);
+
+  expectTestsPass("async().validate() forwards to directory().validate", () {
+    test('test', () {
+      scheduleSandbox();
+
+      d.dir('dir', [
+        d.file('file1.txt', 'contents1'),
+        d.file('file2.txt', 'contents2')
+      ]).create();
+
+      d.async(pumpEventQueue().then((_) {
+        return d.dir('dir', [
+          d.file('file1.txt', 'contents1'),
+          d.file('file2.txt', 'contents2')
+        ]);
+      })).validate();
+    });
+  });
+
+  expectTestsPass("async().create() fails if directory().create fails", () {
+    var errors;
+    test('test 1', () {
+      scheduleSandbox();
+
+      currentSchedule.onException.schedule(() {
+        errors = currentSchedule.errors;
+      });
+
+      d.async(pumpEventQueue().then((_) {
+        return d.dir('dir', [
+          d.file('file1.txt', 'contents1'),
+          d.file('file2.txt', 'contents2')
+        ]);
+      })).validate();
+    });
+
+    test('test 2', () {
+      expect(errors, everyElement(new isInstanceOf<ScheduleError>()));
+      expect(errors.length, equals(1));
+      expect(errors.first.error,
+          matches(r"^Directory not found: '[^']+[\\/]dir'\.$"));
+    });
+  }, passing: ['test 2']);
+
+  expectTestsPass("async().load() fails", () {
+    test('test', () {
+      scheduleSandbox();
+
+      expect(d.async(new Future.immediate(d.file('name.txt')))
+              .load('path').toList(),
+          throwsA(equals("Async descriptors don't support load().")));
+    });
+  });
+
+  expectTestsPass("async().read() fails", () {
+    test('test', () {
+      scheduleSandbox();
+
+      expect(d.async(new Future.immediate(d.file('name.txt'))).read().toList(),
+          throwsA(equals("Async descriptors don't support read().")));
+    });
+  });
 }
 
 void scheduleSandbox() {