PHPUnit tests that involve image rendering are currently marked as "incomplete" as Jenkins doesn't have access to Instant Commons.

@matmarex recommended doing this to generate images for testing purposes:

We do this in core for the parser tests. In /tests/parser/ParserTestRunner.php, a fake-ish upload backend is created, and several files "uploaded" into it. See createRepoGroup() for creating the backends, setupUploads() (and setupUploadBackend()) for creating the uploads, and teardownUploadBackend() for cleaning them up afterwards. I'm not sure how easy this code will be to extricate…