Mocking apache.commons.io.IOUtils class

Question

I need to mock toByteArray() of apache.commons.io.IOUtils class. I've a code snippet like ths:

PowerMockito.mockStatic(IOUtils.class);
PowerMockito.when(IOUtils.toByteArray(any(InputStream.class))).thenReturn(mockByteArray);

But I'm getting NullPointerException from org.apache.commons.io.IOUtils.copyLarge() function.

Answer 1

It looks like the method is not mocked and the real method is called instead.

PowerMock uses special test runner that can mock static methods.

Put @RunWith(PowerMockRunner.class) and @PrepareForTest(IOUtils.class) annotations on your test class.

See example at docs