How to mock local variable obtained from another method of tested class?

Question

I have following class

class MyClass{
   public void m(InputStream is){
       ...
       Parser eParser = getExcelFileParser();
       eParser.parse(is);
       ...
       eParser.foo();
       eParser.bar();

   }
   public ExcelFileParser getExcelFileParser(){
       ...
   } 
}

How to write unit test for method m at this situation? I want to mock eParser object only.

Is it possible?

I use Mockito and PowerMockito

Solution

You can do what you want in Mockito (no PowerMock needed) using a spy without changing your code at all.

In your unit test you need to do something like the following:

ExcelFileParser parser = mock(ExcelFileParser.class);
MyClass myClass = spy(new MyClass());
doReturn(parser).when(myClass).getExcelFileParser();

Comments

[user1309663]

Then use Mockito to mock the getAnotherObject, eg when(myClass.getAnotherObject()).thenReturn(myNewMockObject)

[geoand]

Yes! The spy only replaces the methods you tell.it to