My sense is that 'URI.create("kfs://dev104:20000/")' could be replaced with something like 'URI.create("kfs://bogus/")', since no network access should be made during this test. Is that right?
The version of the FileSystem API that's implemented by this patch is not the current trunk version. In particular, getFileStatus() must be implemented, listFileStatus() should be implemented instead of listPaths(), and many other deprecated methods should not be implemented (getReplication, isDirectory, getLength, etc.), but instead rely on the base class implementation in terms of getFileStatus().
Finally, the bufferSize parameter is no longer supported by FSDataInputStream and FSDataOutputStream. Instead, one should interpolate a BufferedInputStream and an FSBufferedInputStream respectively to add buffering to KFS's streams.