So lets see if I understand this test.
1. Create a fake element
2. Call resize images on it with SHORT_CACHE profile which will call setAttribute on the elements 'src' and assert that the url has 'c2' in it
3. set the setAttribute of the fake element to check for a long cache url
4. call image resize on the element with LONG_CACHE, which calls setAttribute, which asserts that the url matches one generated for a long cache profile

Took me a minute to decipher. Might warrant a comment.