René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Running tests on Windows causes cmd windows to rapidly pop up and disappear","articleBody":"When I try running the tests on Windows, after a certain point the tests will suddenly start spawning and killing cmd windows rapidly. Each window shows up for a fraction of a second, and disappears. \r\n\r\nFrom one perspective, this is a non-issue: the temporary windows always disappear and the tests appear to finish and complete successfully. On the other hand, it's sort of alarming: I ran tests and switched over to my browser, and had a mild moment of panic when these cmd windows suddenly starting showing up and stealing focus.\r\n\r\nI'm assuming this related to the recent work we've been doing with the windows daemon code: I can repro this fairly quickly by running `pytest -k Daemon` using both Powershell and the standard command prompt on Windows 10, and this behavior appears to have been introduced by https://github.com/python/mypy/commit/abd319ab80d476f14e96918d5615fa0ac5b41d75. \r\n\r\nI think ideally we'd stop making these windows appear and disappear. If that's not possible, we could instead maybe do one of the following:\r\n\r\n1. Have the windows spawn in the background (so they don't steal focus).\r\n2. Move the daemon-related tests out of `pytest-fast` or something so that users can opt-out of these tests by running `py -3 ./runtests.py pytest-fast` or something similar.\r\n3. Document that this is expected behavior somewhere.\r\n","author":{"url":"https://github.com/Michael0x2a","@type":"Person","name":"Michael0x2a"},"datePublished":"2018-12-03T03:38:38.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/5991/mypy/issues/5991"}