Expose Service Describer in Dart mojo package

mojo/dart/apptests/dart_apptests/lib/src/service_describer_apptests.dart

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+library service_describer_apptests;
+
+import 'dart:async';
+
+import 'package:mojo_apptest/apptest.dart';
+import 'package:mojo/application.dart';
+import 'package:mojo/bindings.dart';
+import 'package:mojo/core.dart';
+import 'package:mojo/mojo/bindings/types/mojom_types.mojom.dart' as mojom_types;
+import 'package:mojo/mojo/bindings/types/service_describer.mojom.dart'
+    as service_describer;
+import 'package:_mojo_for_test_only/test/echo_service.mojom.dart'
+    as echo_service;
+
+// Tests that demonstrate that a service describer is able to obtain the same
+// mojom type information present in a service's service description.
+// If the descriptions match, it means that you can see what services are
+// described by a mojo application without importing any of their mojom files.
+tests(Application application, String url) {
+  group('Service Describer Apptests', () {
+    test('Echo Service Verification', () async {
+      var serviceDescriberProxy =
+          new service_describer.ServiceDescriberProxy.connectToService(
+              application, "mojo:dart_echo_with_service_describer");
+
+      var serviceDescriptionProxy =
+          new service_describer.ServiceDescriptionProxy.unbound();
+      await serviceDescriberProxy.ptr
+          .describeService("test::EchoService", serviceDescriptionProxy);
+
+      expect(serviceDescriptionProxy.impl, isNotNull);
+      expect(serviceDescriptionProxy.ptr, isNotNull);
+
+      // Compare the service description obtained by the service describer and
+      // the expected description taken from the echo service import.
+      var sd = serviceDescriptionProxy.ptr;
+      var ed = echo_service.EchoServiceStub.serviceDescription;
+
+      Function identity = (v) => v;
+
+      // Top-level Mojom Interfaces must match.
+      mojom_types.MojomInterface a =
+          (await sd.getTopLevelInterface()).mojomInterface;
+      mojom_types.MojomInterface b = ed.getTopLevelInterface(identity);
+      _compare(a, b);
+
+      String interfaceID = "echo_service_EchoService__";
+      mojom_types.MojomInterface c =
+          (await sd.getTypeDefinition(interfaceID)).type.interfaceType;
+      mojom_types.MojomInterface d =
+          ed.getTypeDefinition(interfaceID, identity).interfaceType;
+      _compare(a, c);
+      _compare(c, d);
+
+      // Check that the mojom type definitions match between mappings.
+      // For simplicity, check in a shallow manner.
+      var actualDescriptions = (await sd.getAllTypeDefinitions()).definitions;
+      var expectedDescriptions = ed.getAllTypeDefinitions(identity);
+      actualDescriptions.keys.forEach((String key) {
+        var a = actualDescriptions[key];
+        var e = expectedDescriptions[key];
+        expect(e, isNotNull);
+        expect(a.runtimeType, equals(e.runtimeType));
+      });
+
+      await serviceDescriptionProxy.close();
+      await serviceDescriberProxy.close();
+    });
+  });
+}
+
+// Helper to compare two mojom interfaces for matches.
+void _compare(mojom_types.MojomInterface a, mojom_types.MojomInterface b) {
+  // Match the generated decl data.
+  expect(a.declData, isNotNull);
+  expect(b.declData, isNotNull);
+  expect(a.declData.shortName, equals(b.declData.shortName));
+  expect(a.declData.fullIdentifier, equals(b.declData.fullIdentifier));
+
+  // Verify that the number of methods matches the expected ones.
+  expect(a.methods.length, equals(b.methods.length));
+
+  // Each MojomMethod must be named, typed, and "ordinal"ed the same way.
+  a.methods.forEach((int ordinal, mojom_types.MojomMethod methodA) {
+    mojom_types.MojomMethod methodB = b.methods[ordinal];
+    expect(methodB, isNotNull);
+
+    // Compare declData.
+    expect(methodA.declData, isNotNull);
+    expect(methodB.declData, isNotNull);
+    expect(methodA.declData.shortName, equals(methodB.declData.shortName));
+
+    // Lastly, compare parameters and responses (generally).
+    expect(methodA.parameters.fields.length,
+        equals(methodB.parameters.fields.length));
+    mojom_types.MojomStruct responseA = methodA.responseParams;
+    mojom_types.MojomStruct responseB = methodB.responseParams;
+    expect(responseA == null, equals(responseB == null));
+    if (responseA != null) {
+      expect(responseA.fields.length, equals(responseB.fields.length));
+    }
+  });
+}