Comment 6 for bug 419691

@jml the benefits listed:
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It's probably also worth enumerating the advantages of using testresources:

 - the main one is that it will make our tests easier to understand, the requirements of a test will be more explicit.
 - we can also more easily use other test runners, which will probably make projects like parallelizing the test run easier.
 - running a small number of tests locally will often be quicker, as test fixtures will be more minimal.
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Are pretty clear to me:
 - clearer test dependencies
 - easier use of other test runners (such as trial, tribunal, or [say, bzr-selftest --parallel=ec2])
 - faster runs of select tests by better dependency management