This is from discussion in
HADOOP-14170, as Steve commented:
...it's time to move this to JUnit 4, annotate all tests with @test, and make the test cases skip if they don't have the test FS defined. JUnit 3 doesn't support Assume, so when I do test runs without the s3n or s3 fs specced, I get lots of errors I just ignore.
...Move to Junit 4, and, in our own code, find everywhere we've subclassed a method to make the test a no-op, and insert an Assume.assumeTrue(false) in there so they skip properly.