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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"assert mods.pop(0) == 'tests' errors for multiprocess tests on OSX","articleBody":"I'm testing OSX builds using Matt Terry's build grid.  All the matplotlib builds are giving multiple errors like this:\n\n```\n======================================================================\nFAIL: Failure: AssertionError ()\n----------------------------------------------------------------------\nTraceback (most recent call last):\n  File \"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/nose/loader.py\", line 284, in generate\n    for test in g():\n  File \"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/testing/decorators.py\", line 152, in test\n    baseline_dir, result_dir = _image_directories(self._func)\n  File \"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/testing/decorators.py\", line 303, in _image_directories\n    assert mods.pop(0) == 'tests'\nAssertionError\n```\n\nSee: https://s3.amazonaws.com/archive.travis-ci.org/jobs/30794968/log.txt\n\nIt's not clear where the failures are coming from, but this is an excerpt from the stdout of the tests.\n\n```\nmatplotlib.tests.test_triangulation.test_tri_smooth_contouring.test ... ok\nFailure: AssertionError () ... FAIL\nmatplotlib.tests.test_triangulation.test_triinterpcubic_C1_continuity ... ok\nmatplotlib.tests.test_triangulation.test_tri_smooth_gradient.test ... ok\nFailure: AssertionError () ... FAIL\nFailure: AssertionError () ... FAIL\nFailure: AssertionError () ... FAIL\nFailure: AssertionError () ... FAIL\nFailure: AssertionError () ... FAIL\nFailure: AssertionError () ... FAIL\nFailure: AssertionError () ... FAIL\nFailure: AssertionError () ... FAIL\nFailure: AssertionError () ... FAIL\nFailure: AssertionError () ... FAIL\nFailure: AssertionError () ... FAIL\nFailure: AssertionError () ... FAIL\nmatplotlib.tests.test_transforms.test_pre_transform_plotting.test ... ok\n```\n\nI can replicate the failures on my laptop in a clean virtual machine, but only when running the tests via the multiprocessing plugin:\n\n```\npython ../matplotlib/tests.py -sv --processes=8 --process-timeout=300\n```\n\nRunning in single process mode gives no failures.  Does anyone have any idea how I could investigate further?\n","author":{"url":"https://github.com/matthew-brett","@type":"Person","name":"matthew-brett"},"datePublished":"2014-07-27T02:31:13.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/3314/matplotlib/issues/3314"}