simplify tester creation idiom

[maciejmikosik]

Find a simpler way to create tester implementations.
Currently is looks like this:

  private static Tester<Object> tester(final Object argument) {
    return new Tester<Object>() {
      public Test test(final Object item) {
        String name = " ... ";
        return new TestCase(name) {
          protected void runTest() throws Throwable {
            ...
            assert ...
          }
        };
      }
    };
  }

[maciejmikosik]

created BodyTester which helps implementing Tester 222a189

New idiom is

  private static Tester<Object> tester(final Object argument) {
    return new BodyTester<Object>() {
      protected String name(Object item) {
        return " ... ";
      }

      protected void body(Object item) throws Throwable {
         ...
         assert ...
      }
    };
  }