Android Unit Tests : Mock context that also returns a looper

Question

Here is my sample code :
SomeClass.java

public class SomeClass {
    public SomeClass(Context mContext) {
        final Looper looper = mContext.getMainLooper();
        Handler mHandler = new Handler(looper);
    }
}

SomeClassTest.java

public class SomeClassTest {
    private SomeClass mSomeClass;

    @Mock
    private Context mContext;

    @before
    public void setup(){
        mSomeClass = new SomeClass(mContext);
    }
}

The above code generates a NullPointerException at the line final Looper looper = mContext.getMainLooper(); in SomeClass.
How can I setup the mock context object to avoid this exception ?

Answer 1

Assuming you are using Mockito, you can add mock behavior to mock objects:

public class SomeClassTest {
    private SomeClass mSomeClass;
    private Looper mLooper;

    @before
    public void setup(){
        mLooper = mock(Looper.class);
        Context ctx = mock(Context.class);
        when(ctx.getMainLooper()).thenReturn(mLooper);
        mSomeClass = new SomeClass(mContext);
    }
}