08. Argument Matchers

Argument Matchers

Mocking Variable Input

Our previous example returned a specific input when fizzBuzz was called with a value of 1.

when(salesService.fizzBuzz(1)).thenReturn(input);

You can use the ArgumentMatchers class to accept variable input instead. For example, ArgumentMatchers.anyInt() accepts any integer value.

@Test
public void fancyBusiness_getsEvenNumber_returnsBaz() {
   when(salesService.fizzBuzz(anyInt())).thenReturn("2");
   // verify that no matter what number we pass into fancyBusiness, 
   // we'll return "Baz" if fizzbuzz yields an even number
   for(int i = 0; i < 100; i++) {
       Assertions.assertEquals("Baz", userService.fancyBusiness(i));
   }
}

Types of ArgumentMatchers

Type Matchers:

• Primitives: anyInt(), anyFloat(), anyBoolean(), etc.
• Objects: any(), any(Class)
• Collections: anyCollection(), anyIterable(), anyList(), anyMap(), anySet()

Value Matchers:

• Primitives: eq(val)
• Objects: eq(obj), same(obj), refEq(obj)