Mockito does not Trigger doReturn on super method

Question

I am testing some legacy code and trying to mock some behavior in the superclass. Strangely mockito does not trigger and return my expected value, in some cases, it even throws a NullpointerException on the doReturn line. Here is the relevant code:

class to test

package mypackage;

import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;

public abstract class MyClass extends PushbackInputStream
{


  public MyClass(InputStream in)
  {
    super(in, 20);
  }

  protected final void checkIaikPkcs7() throws IOException
  {
    byte[] buffer = getInstantiatedByteArray(20);
    if (super.read(buffer, 0, buffer.length) != buffer.length)
    {
      throw new IOException("unable to read needed data");
    }
    ...
  }

  protected byte[] getInstantiatedByteArray(int size)
  {
    return new byte[size];
  }
}

class with tests

public class MyClassTest
{
  private MyClass spy;
  private InputStream inputStreamMock;

  @Before
  public void setUp() throws Exception
  {
    this.inputStreamMock = mock(InputStream.class);
    this.spy = spy(new MyObjectClassExtendingMyClass(inputStreamMock));
  }

  @After
  public void tearDown() throws Exception
  {
    this.spy = null;
    this.inputStreamMock = null;
  }


  @Test
  public void testCheckIaikPkcs7() throws IOException
  {
    //assure that read is called with exactly the same parameters in mock and implementation
    byte[] byteArray = new byte[20];
    doReturn(byteArray).when(this.spy).getInstantiatedByteArray(20);

    // want 20 returned, but the Test returns 0 (propably not recognizing this line)
    doReturn(20).when(this.spy).read(byteArray, 0, byteArray.length);
    this.spy.checkIaikPkcs7();
  }

}

alternatively, I replaced the doReturn(20).... with

    doReturn(20).when(this.spy).read(any(), any(), any());

but then I get a NullPointerException. I cannot see where I went wrong and Help would be realy appreciated.

Thank you so far

Answer 1

If you don't need to override read, just use this.read instead of super.read and your code will work.

See Mockito How to mock only the call of a method of the superclass

Second problem with NullPointerException: You need to use anyInt(), not any() for params that accept primitive int