Issue #75: wired CacheLoader where applicable.

If it adds to readability of the test, I can add a `fail()` call as the last line of the method, as it should be unreachable. However, I think that sprinkling this pattern verbatim throughout the class is an eyesore and really doesn't provide much value:

    try {
       // some test logic
       fail("Expected exception!");
    } catch (Exception expected) {
      // passed
    }