Check only the descriptor identity before comparing messages, not the class identity.

RELNOTES=Check only the descriptor identity before comparing messages in ProtoSubject.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=186061377

Author: torquestomp

extensions/proto/src/main/java/com/google/common/truth/extensions/proto/ProtoSubject.java

@@ -20,6 +20,7 @@
 import static com.google.common.collect.Lists.asList;
 import static com.google.common.truth.extensions.proto.FieldScopeUtil.asList;
 
+import com.google.common.base.Objects;
 import com.google.common.truth.FailureMetadata;
 import com.google.common.truth.Subject;
 import com.google.protobuf.Descriptors.FieldDescriptor;
@@ -117,9 +118,17 @@ public ProtoFluentAssertion reportingMismatchesOnly() {
     return usingConfig(config.reportingMismatchesOnly());
   }
 
+  private static boolean notMessagesWithSameDescriptor(
+      @Nullable Message actual, @Nullable Object expected) {
+    if (actual != null && expected instanceof Message) {
+      return actual.getDescriptorForType() != ((Message) expected).getDescriptorForType();
+    }
+    return true;
+  }
+
   @Override
   public void isEqualTo(@Nullable Object expected) {
-    if (actual() == null || expected == null || actual().getClass() != expected.getClass()) {
+    if (notMessagesWithSameDescriptor(actual(), expected)) {
       super.isEqualTo(expected);
     } else {
       DiffResult diffResult = makeDifferencer().diffMessages(actual(), (Message) expected);
@@ -137,24 +146,22 @@ public void isEqualTo(@Nullable Object expected) {
    * without throwing any exceptions.
    */
   boolean testIsEqualTo(@Nullable Object expected) {
-    if (actual() == null || expected == null) {
-      return actual() == expected; // Only true if both null.
-    } else if (actual().getClass() != expected.getClass()) {
-      return false;
+    if (notMessagesWithSameDescriptor(actual(), expected)) {
+      return Objects.equal(actual(), expected);
     } else {
       return makeDifferencer().diffMessages(actual(), (Message) expected).isMatched();
     }
   }
 
   @Override
   public void isNotEqualTo(@Nullable Object expected) {
-    if (actual() == null || expected == null || actual().getClass() != expected.getClass()) {
+    if (notMessagesWithSameDescriptor(actual(), expected)) {
       super.isNotEqualTo(expected);
     } else {
       DiffResult diffResult = makeDifferencer().diffMessages(actual(), (Message) expected);
       if (diffResult.isMatched()) {
         failWithRawMessage(
-            failureMessage(/* expectedEqual = */ false)
+            failureMessage(/* expectedEqual= */ false)
                 + "\n"
                 + diffResult.printToString(config.reportMismatchesOnly()));
       }

extensions/proto/src/test/java/com/google/common/truth/extensions/proto/ProtoSubjectTest.java

@@ -15,6 +15,7 @@
  */
 package com.google.common.truth.extensions.proto;
 
+import com.google.protobuf.DynamicMessage;
 import com.google.protobuf.InvalidProtocolBufferException;
 import com.google.protobuf.Message;
 import com.google.protobuf.UnknownFieldSet;
@@ -37,6 +38,16 @@ public ProtoSubjectTest(TestType testType) {
     super(testType);
   }
 
+  @Test
+  public void testDifferentClasses() throws InvalidProtocolBufferException {
+    Message message = parse("o_int: 3");
+    DynamicMessage dynamicMessage =
+        DynamicMessage.parseFrom(message.getDescriptorForType(), message.toByteString());
+
+    expectThat(message).isEqualTo(dynamicMessage);
+    expectThat(dynamicMessage).isEqualTo(message);
+  }
+
   @Test
   public void testIgnoringFieldAbsence() {
     Message message = parse("o_int: 3");