Support serialization of Mockito mocks

I’m writing a unit-test for Android app, which creates a mock of serializable custom class and tries to serialize it. It works fine in JUnit test when I’m running it in JVM, but fails with following error when I’m running it as Android test in emulator:

Full gist of error message.

W/System.err: java.io.NotSerializableException: com.android.dx.mockito.InvocationHandlerAdapter
W/System.err:     at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1224)
W/System.err:     at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1584)
W/System.err:     at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1549)
W/System.err:     at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1472)

Here is my code (Android test gist):

Entity serializableMock = mock(Entity.class, Mockito.withSettings().serializable());
try {
    ObjectOutputStream out = new ObjectOutputStream(new ByteArrayOutputStream());
    out.writeObject(serializableMock);
} catch (IOException e) {//catching NotSerializableException here} 

Entity:

package org.test;
public class Entity implements Serializable {
    public String str;
    // getters/setters
}

Gradle dependencies:

androidTestCompile 'org.mockito:mockito-core:2.4.0'
androidTestCompile 'com.linkedin.dexmaker:dexmaker-mockito:2.2.0'
androidTestCompile "com.android.support:support-annotations:25.0.0"
androidTestCompile 'com.android.support.test:runner:0.5'
androidTestCompile 'com.android.support.test:rules:0.5'

How to properly serialize mock object on Android?

[drewhannay]

That was my first try. 😉

I don’t think that will work though…the actual code needed to make serializable mocks behave as expected is pretty complex. It may be worth checking out the new mockito-android project from the mockito team if this is important to you.

[engintekin]

@drewhannay would it be a hack to make com.android.dx.mockito.InvocationHandlerAdapter Serializable?