This page aims at listing situations that were met which led to flaky tests. If you encounter flaky tests and do not understand why, you can have a look at the list.

If you met such situation and solved it, please document it there, so that others may benefit from your experience.

File improperly closed in Java code

In a test in version 19.04.0+dfsg-1 of libsis-jhdf5-java, calling the close() method of some object from a class implementing had been forgotten, so that system resources associated with it (namely, a file) were not released. Some other tests were run afterwards, and behaved in various ways:

This seems to be due to the garbage collector behaving differently in those environments, sometimes releasing the resources at the end of the test that failed to do so, sometimes keeping them locked until the very end of the test session. We fixed the issue by invocating the close() method.