René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"check_figures_equal decorator reuses figures if called multiple times inside a single test.","articleBody":"\u003c!--To help us understand and resolve your issue, please fill out the form to the best of your ability.--\u003e\r\n\u003c!--You can feel free to delete the sections that do not apply.--\u003e\r\n\r\n### Bug report\r\n\r\n**Bug summary**\r\n\r\nWhen running a test suite with multiple tests using check_figures_equal, figures are re-used, causing plot elements to become \"stacked\", causing tests to unexpectedly fail.\r\n\r\n**Code for reproduction**\r\n\r\n```python\r\nfrom matplotlib.testing.decorators import check_figures_equal\r\nfrom matplotlib import pyplot as plt\r\n\r\n@check_figures_equal(extensions=[\"png\"])\r\ndef test_red_line_first(test_figure, reference_figure):\r\n    red_circle = plt.Circle((0, 0), 0.2, color='r', clip_on=False)\r\n    reference_figure.add_artist(red_circle)\r\n    reference_figure.subplots().plot([0,1,2], [3,4,5], color='red')    \r\n\r\n\r\n@check_figures_equal(extensions=[\"png\"])\r\ndef test_blue_line_second(test_figure, reference_figure):\r\n    blue_circle = plt.Circle((1, 1), 0.2, color='b', clip_on=False)\r\n    reference_figure.add_artist(blue_circle)\r\n    reference_figure.subplots().plot([0,1,2], [4,4,4], color='blue')\r\n\r\n\r\n@check_figures_equal(extensions=[\"png\"])\r\ndef test_green_line_third(test_figure, reference_figure):\r\n    green_circle = plt.Circle((1, 0), 0.2, color='g', clip_on=False)\r\n    reference_figure.add_artist(green_circle)\r\n    reference_figure.subplots().plot([0,1,2], [5,4,3], color='green')\r\n```\r\n\r\nrunning as:\r\n`pytest .\\mpl_figure_equal_test.py`\r\n\r\n**Actual outcome**\r\nReference Screenshots:\r\n![test_red_line_first-expected](https://user-images.githubusercontent.com/5263073/63228487-3e4f3680-c1b9-11e9-8452-e8b6a84f6b9f.png)\r\n![test_blue_line_second-expected](https://user-images.githubusercontent.com/5263073/63228488-4018fa00-c1b9-11e9-8ac0-1b27d2f3baa2.png)\r\n![test_green_line_third-expected](https://user-images.githubusercontent.com/5263073/63228490-414a2700-c1b9-11e9-8181-f40ed360201b.png)\r\n\r\n\r\n**Expected outcome**\r\nReference Screenshots:\r\n![test_red_line_first-expected](https://user-images.githubusercontent.com/5263073/63228494-6048b900-c1b9-11e9-95a5-f1d3e2e362b5.png)\r\n![test_blue_line_second-expected](https://user-images.githubusercontent.com/5263073/63228495-68a0f400-c1b9-11e9-8a23-0953f2184c27.png)\r\n![test_green_line_third-expected](https://user-images.githubusercontent.com/5263073/63228496-69d22100-c1b9-11e9-82fa-cb8768b0bf2c.png)\r\n\r\n\u003c!--A description of the expected outcome from the code snippet--\u003e\r\n\u003c!--If this used to work in an earlier version of Matplotlib, please note the version it used to work on--\u003e\r\n\r\n**Matplotlib version**\r\n\u003c!--Please specify your platform and versions of the relevant libraries you are using:--\u003e\r\n  * Operating system: `Windows 10`\r\n  * Matplotlib version: `matplotlib            3.1.0`\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): `TkAgg`\r\n  * Python version: `3.7.3`\r\n  * Jupyter version (if applicable):\r\n  * Other libraries:  `pytest                4.5.0`\r\n\r\neverything installed via pip\r\n\r\n\u003c!--Please tell us how you installed matplotlib and python e.g., from source, pip, conda--\u003e\r\n\u003c!--If you installed from conda, please specify which channel you used if not the default--\u003e\r\n\r\nhttps://github.com/matplotlib/matplotlib/blob/e86c9cd7105e107589220286d55cd9ffc3bfeb64/lib/matplotlib/testing/decorators.py#L394-L395\r\n\r\nI'm guessing these lines are at fault, and might need some kind of other information to distinguish them?\r\n","author":{"url":"https://github.com/andrewzwicky","@type":"Person","name":"andrewzwicky"},"datePublished":"2019-08-18T18:14:49.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/15079/matplotlib/issues/15079"}