test: unique artifact filenames to fix a race under paratest - #209
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paratest --functional runs test methods concurrently, and the tests saving source files all wrote to the same var/browser/source path: one test could read the file another test just wrote, failing with the other test's content. Seen on CI where can_save_formatted_json_source and can_save_source_when_exception each read the other's output. Each save now uses a unique filename.
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paratest --functionalruns test methods concurrently, and the file-saving tests all write to the samevar/browser/sourcepaths.catchFileContents()removes the file, runs the callback, then reads it back, so one test can read the file another test just wrote.Seen on this run (#208's first CI pass):
can_save_formatted_json_sourcefailed with the exception dump fromcan_save_source_when_exceptionon one job, and the mirror image on another. The two tests come from theKernelBrowserTeststrait, so two classes race on the samesource.txteven across classes.Each save now uses a unique filename (
random_bytesprefix). With the fix I could no longer reproduce anycan_save_*failure across 8 localparatest --functionalruns.