Add Client-side OAuth2 to HTTP connections

Implement client-side OAuth in non-local HTTP connections.  Also add tests to
verify that the different modes of connection are set up correctly.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=147636222

javatests/google/registry/tools/DefaultRequestFactoryModuleTest.java

@@ -0,0 +1,109 @@
+// Copyright 2017 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.tools;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.mockito.Matchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyZeroInteractions;
+import static org.mockito.Mockito.when;
+
+import com.google.api.client.auth.oauth2.Credential;
+import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
+import com.google.api.client.http.HttpRequest;
+import com.google.api.client.http.HttpRequestFactory;
+import com.google.api.client.http.HttpRequestInitializer;
+import com.google.api.client.util.store.AbstractDataStoreFactory;
+import com.google.common.net.HostAndPort;
+import google.registry.testing.Providers;
+import java.io.IOException;
+import javax.inject.Provider;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+import org.mockito.ArgumentCaptor;
+
+@RunWith(JUnit4.class)
+public class DefaultRequestFactoryModuleTest {
+
+  private static final Credential FAKE_CREDENTIAL = new Credential(
+      new Credential.AccessMethod() {
+        @Override
+        public void intercept(HttpRequest request, String accessToken) throws IOException {}
+
+        @Override
+        public String getAccessTokenFromRequest(HttpRequest request) {
+          return "MockAccessToken";
+        }
+      });
+
+  private static final String TEST_CLIENT_SECRET_FILENAME =
+      "/google/registry/tools/resources/client_secret_UNITTEST.json";
+
+  // Mocks.
+  AbstractDataStoreFactory dataStoreFactory = mock(AbstractDataStoreFactory.class);
+  DefaultRequestFactoryModule.Authorizer authorizer =
+      mock(DefaultRequestFactoryModule.Authorizer.class);
+  Provider<Credential> credentialProvider = Providers.of(FAKE_CREDENTIAL);
+
+  // Captor for client secrets.
+  ArgumentCaptor<GoogleClientSecrets> secrets = ArgumentCaptor.forClass(GoogleClientSecrets.class);
+
+  DefaultRequestFactoryModule module = new DefaultRequestFactoryModule();
+
+  @Before
+  public void setUp() {
+    RegistryToolEnvironment.UNITTEST.setup();
+  }
+
+  @Test
+  public void test_getCredential() throws Exception {
+    when(authorizer.authorize(any(GoogleClientSecrets.class))).thenReturn(FAKE_CREDENTIAL);
+    Credential cred = module.provideCredential(
+        dataStoreFactory,
+        authorizer,
+        TEST_CLIENT_SECRET_FILENAME);
+    assertThat(cred).isSameAs(FAKE_CREDENTIAL);
+    verify(authorizer).authorize(secrets.capture());
+    assertThat(secrets.getValue().getDetails().getClientId()).isEqualTo(
+        "UNITTEST-CLIENT-ID");
+  }
+
+  @Test
+  public void test_provideHttpRequestFactory_localhost() throws Exception {
+    // Make sure that localhost creates a request factory with an initializer.
+    HttpRequestFactory factory =
+        module.provideHttpRequestFactory(new AppEngineConnectionFlags(
+                HostAndPort.fromParts("localhost", 1000)),
+            credentialProvider);
+    HttpRequestInitializer initializer = factory.getInitializer();
+    assertThat(initializer).isNotNull();
+    assertThat(initializer).isNotSameAs(FAKE_CREDENTIAL);
+    verifyZeroInteractions(authorizer);
+  }
+
+  @Test
+  public void test_provideHttpRequestFactory_remote() throws Exception {
+    // Make sure that example.com creates a request factory with the UNITTEST client id but no
+    // initializer.
+    HttpRequestFactory factory =
+        module.provideHttpRequestFactory(new AppEngineConnectionFlags(
+                HostAndPort.fromParts("example.com", 1000)),
+            credentialProvider);
+    assertThat(factory.getInitializer()).isSameAs(FAKE_CREDENTIAL);
+  }
+}