Raise TypeError when WATCHMAN_CHECKS is a string instead of a sequence#231
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mwarkentin merged 1 commit intomainfrom Mar 8, 2026
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Fixes #149. When WATCHMAN_CHECKS is set with parentheses but without a trailing comma (e.g. `('single.check')`), Python treats it as a plain string. Calling `frozenset()` on a string iterates over characters, leading to a confusing ImportError. This adds an early isinstance check with a clear error message guiding the user to use a list or trailing comma. Made-with: Cursor
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Summary
WATCHMAN_CHECKSis defined with parentheses but without a trailing comma (e.g.WATCHMAN_CHECKS = ('single.check')), Python treats it as a plain string rather than a tuple.frozenset()then iterates over individual characters, producing a confusingImportErrorlike"h doesn't look like a module path".isinstance(WATCHMAN_CHECKS, str)check inget_checks()that raises a clearTypeErrorwith guidance on how to fix the setting.TypeErroris raised whenWATCHMAN_CHECKSis accidentally a string.Test plan
test_get_checks_raises_type_error_when_checks_is_a_stringpassesMade with Cursor