Add support for equals, hashCode and toString on proxy instances. (#68)

* Add support for equals, hashCode and toString on proxy instances.

Author: nwbirnie

google-ads/src/main/java/com/google/ads/googleads/lib/catalog/ApiCatalogImpl.java

@@ -20,8 +20,8 @@
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSortedSet;
+import com.google.common.reflect.AbstractInvocationHandler;
 import com.google.common.reflect.Reflection;
-import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Method;
 import java.util.Collection;
 import java.util.SortedSet;
@@ -68,11 +68,12 @@ public GoogleAdsAllVersions createAllVersionsClient(
     Preconditions.checkNotNull(
         credentials, "Credentials are required to create GoogleAdsAllVersions interface.");
     return Reflection.newProxy(
-        GoogleAdsAllVersions.class, new GoogleAdsAllVersionsInvocationHandler(provider, credentials));
+        GoogleAdsAllVersions.class,
+        new GoogleAdsAllVersionsInvocationHandler(provider, credentials));
   }
 
   /** A dynamic proxy implementation of GoogleAdsAllVersions. */
-  private static class GoogleAdsAllVersionsInvocationHandler implements InvocationHandler {
+  private static class GoogleAdsAllVersionsInvocationHandler extends AbstractInvocationHandler {
 
     private final ImmutableMap<Method, Object> clientFactories;
 
@@ -83,7 +84,7 @@ public GoogleAdsAllVersionsInvocationHandler(
     }
 
     @Override
-    public Object invoke(Object proxy, Method method, Object[] args) {
+    protected Object handleInvocation(Object proxy, Method method, Object[] args) {
       return clientFactories.get(method);
     }
 
@@ -94,8 +95,7 @@ private static ImmutableMap<Method, Object> cacheClientFactories(
       for (Method method : GoogleAdsAllVersions.class.getMethods()) {
         builder.put(
             method,
-            GoogleAdsVersionFactory.createProxy(
-                method.getReturnType(), provider, credentials));
+            GoogleAdsVersionFactory.createProxy(method.getReturnType(), provider, credentials));
       }
       return builder.build();
     }

google-ads/src/main/java/com/google/ads/googleads/lib/catalog/GoogleAdsVersionFactory.java

@@ -23,6 +23,7 @@
 import com.google.auth.Credentials;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.reflect.AbstractInvocationHandler;
 import com.google.common.reflect.Reflection;
 import java.io.IOException;
 import java.lang.reflect.InvocationHandler;
@@ -65,7 +66,7 @@ public static <T> T createProxy(
   }
 
   /** Implements InvocationHandler for the dynamic proxy implementation of VersionDescriptor. */
-  private static class VersionDescriptorInvocationHandler implements InvocationHandler {
+  private static class VersionDescriptorInvocationHandler extends AbstractInvocationHandler {
 
     private final ImmutableMap<Class, Method> clientCreators;
     private final ImmutableMap<Method, Method> settingsBuilders;
@@ -94,7 +95,7 @@ private VersionDescriptorInvocationHandler(
     }
 
     @Override
-    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+    protected Object handleInvocation(Object proxy, Method method, Object[] args) throws Throwable {
       ClientSettings settings = createClientSettings(method);
       return createServiceClient(method.getReturnType(), settings);
     }

google-ads/src/test/java/com/google/ads/googleads/lib/GoogleAdsClientTest.java

@@ -16,6 +16,7 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertThat;
@@ -338,13 +339,74 @@ public void exceptionTransformedToGoogleAdsException() {
     }
   }
 
+  /** Ensure that can set endpoint on default transport channel. */
   @Test
   public void transportChannelProvider_defaultRequiresEndpoint() {
     assertTrue(
         "Default TransportChannelProvider must accept endpoint.",
         GoogleAdsClient.newBuilder().getTransportChannelProvider().needsEndpoint());
   }
 
+  /** Ensure that hashCode doesn't collide for a test instance. */
+  @Test
+  public void hashCode_doesNotCollide() {
+    GoogleAdsClient clientA =
+        GoogleAdsClient.newBuilder()
+            .setCredentials(fakeCredentials)
+            .setDeveloperToken(DEVELOPER_TOKEN)
+            .build();
+    GoogleAdsClient clientB =
+        GoogleAdsClient.newBuilder()
+            .setCredentials(fakeCredentials)
+            .setDeveloperToken(DEVELOPER_TOKEN + "asdf")
+            .build();
+    // Granted there could be hash collisions, but this should not happen for this test case.
+    assertNotEquals(
+        "Clients with distinct params should have distinct hashCodes",
+        clientA.hashCode(),
+        clientB.hashCode());
+  }
+
+  /** Ensures that equals is true for A == B. */
+  @Test
+  public void equals_equalIfSameInstance() {
+    GoogleAdsClient client =
+        GoogleAdsClient.newBuilder()
+            .setCredentials(fakeCredentials)
+            .setDeveloperToken(DEVELOPER_TOKEN)
+            .build();
+    assertEquals("same instance should be equal", client, client);
+  }
+
+  /** Ensures that equals is false for A != B, with same config. */
+  @Test
+  public void equals_notEqualIfDifferentInstance() {
+    GoogleAdsClient clientA =
+        GoogleAdsClient.newBuilder()
+            .setCredentials(fakeCredentials)
+            .setDeveloperToken(DEVELOPER_TOKEN)
+            .build();
+    GoogleAdsClient clientB =
+        GoogleAdsClient.newBuilder()
+            .setCredentials(fakeCredentials)
+            .setDeveloperToken(DEVELOPER_TOKEN)
+            .build();
+    assertNotEquals("different instances should not be equal", clientA, clientB);
+  }
+
+  /** Ensures that toString returns a nonnull value with length() > 0. */
+  @Test
+  public void toString_returnsNotNull() {
+    GoogleAdsClient client =
+        GoogleAdsClient.newBuilder()
+            .setCredentials(fakeCredentials)
+            .setDeveloperToken(DEVELOPER_TOKEN)
+            .build();
+    String toString = client.toString();
+    assertNotNull("toString should return a non-null string", toString);
+    assertFalse("toString should return a non-empty string", toString.isEmpty());
+  }
+
   /** Creates an GoogleAdsClient using mock credentials. */
   private GoogleAdsClient createTestGoogleAdsClient() {
     return GoogleAdsClient.newBuilder()