convenience method unit test.java

public String convenient(Object o) {
  return lessConvenient(o, "default");
}

public String lessConvenient(Object o, String suffix) {
  return o.toString() + suffix;
}

// Unit tests
// assume lessConvenient is already tested

@Test
public void convenient_should_invoke_lessConvenient_with_default_suffix() {
  Object o = "word";

  assertEquals(lessConvenient(o, "default"), convenient(o));
}