fix: BaseFloat._check_scalar rejects invalid string values (#3586)#3762
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d-v-b merged 2 commits intozarr-developers:mainfrom Mar 11, 2026
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…lopers#3586) BaseFloat._check_scalar returned True for all strings because the FloatLike type union includes str. This allowed invalid strings like 'not valid' to pass the check and then raise a confusing ValueError in _cast_scalar_unchecked instead of the expected TypeError. Fix _check_scalar to validate string inputs by attempting conversion: - Valid float strings (e.g. 'NaN', 'inf', '-inf', '1.5') return True - Invalid strings (e.g. 'not valid') return False, causing cast_scalar to raise TypeError as expected Add test cases for invalid string inputs to invalid_scalar_params. Fixes zarr-developers#3586
d-v-b
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Mar 11, 2026
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Summary
Fixes #3586.
BaseFloat._check_scalarreturnedTruefor all strings becauseFloatLikeincludesstr. This caused invalid strings like'not valid'to pass the scalar check, then raise a confusingValueErrorin_cast_scalar_uncheckedinstead of the expectedTypeError.Root Cause
FloatLike = SupportsIndex | SupportsFloat | bytes | str, soisinstance('not valid', FloatLike)isTrue. When_cast_scalar_uncheckedcallsnp.float32('not valid')it raisesValueError, notTypeError.Changes
BaseFloat._check_scalarnow validates string inputs by attempting conversion:'NaN','inf','-inf') → returnsTrue(existing behaviour preserved)'not valid', etc.) → returnsFalse, causingcast_scalarto raiseTypeErrorTesting
Added invalid string test cases to
invalid_scalar_paramsforFloat16,Float32, andFloat64.