@Test
  public void mockFieldWithCapturingLimitedToOneInstance() {
    new NonStrictExpectations() {
      {
        mock2.getStr();
        result = "mocked";
      }
    };

    assertNull(preexistingInstance.getStr());

    BaseClass service1 = new DerivedClass("test 1");
    assertNull(service1.str);
    assertEquals("mocked", service1.getStr());

    BaseClass service2 = new BaseClass("test 2");
    assertNull(service2.str);
    assertNull(service2.getStr());

    new Verifications() {
      {
        mock2.getStr();
        times = 1;
        preexistingInstance.getStr();
        times = 1;
      }
    };
  }