docs: fix FsCheck custom generators example for FsCheck 3.x API #4620
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The documentation example used the FsCheck 2.x API (Arb.Default.Int32().Filter()) which is no longer available in FsCheck 3.x. Updated to use the correct FsCheck 3.x Fluent API with ArbMap.Default.GeneratorFor<T>(). Changes: - Use ArbMap.Default.GeneratorFor<T>() instead of Arb.Default - Use .Where() for filtering and .ToArbitrary() to convert - Added alternative example using Gen.Choose for simple ranges - Added custom types example showing LINQ composition - Added test coverage for the documented pattern Fixes #4619
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Code reviewNo issues found. Checked for bugs and CLAUDE.md compliance. |
This was referenced Feb 1, 2026
This was referenced Feb 2, 2026
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Summary
Arb.Default.Int32().Filter())ArbMap.Default.GeneratorFor<T>()Problem
The documentation example at https://tunit.dev/docs/examples/fscheck/#custom-generators didn't compile because
Arb.Defaultis internal in FsCheck 3.x (the version used by TUnit.FsCheck).Changes
ArbMap.Default.GeneratorFor<T>()instead ofArb.Default.Where()for filtering and.ToArbitrary()to convert generatorsGen.Choosefor simple rangesTUnit.Example.FsCheck.TestProjectto verify the documented pattern worksTest plan
PositiveNumbersArePositivetest passes with custom arbitraryFixes #4619