Comment by throwaway3563

Had a flaky unit test that would randomly fail with some random Chinese character in the output.

The test was running a log parsing tool against a temporary file that had a pseudo-SQL syntax where you could “select ... from c:\Users\...\temp\abcd1234.xyz\testdata.dat”. The temporary directory was a randomly generated name so that the folder was guaranteed to be empty before every execution of the test.

The test failed on the rare occasion that the randomly generated temp dir consisted of the letter ‘u’ plus four characters that were valid hex digits. When this happened the randomly generated dir name interacted with the backslash before it and become a Unicode escape sequence. It was easy to fix but that test was flaky for months before anyone worked out why.