Such wars arise when the tests run fine as long as you are the only one testing but fail when more programmers run them. This is most likely caused by resource interference: some tests in your suite allocate resources such as temporary files that are also used by others.
A. van Deursen, L. Moonen, A. Bergh, G. Kok, “Refactoring Test Code”, Technical Report, CWI, 2001.
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