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Fix the "Useful methods" section in the TestData docs #727

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kurtschelfthout merged 3 commits into from
Jan 26, 2026
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Fix the "Useful methods" section in the TestData docs #727

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e3e6cb0
Fix documentation about functions that have been moved to ArbMap
svenvanheugten Jan 23, 2026
3176586
Remove reference to Arb.shrink function that no longer exists
svenvanheugten Jan 23, 2026
466eae1
Re-arrange bullet points in the 'Useful methods' section
svenvanheugten Jan 23, 2026
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9 changes: 4 additions & 5 deletions docs/TestData.fsx
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Expand Up @@ -632,14 +632,13 @@ However, there are some important things to notice that are listed here to avoid
- The same thing with the default DoNotSize generators of the number-like types except Decimal.
- Most of the default generators of the collection types are just "wrappers" around the F# list. Thus, you can assume that they are generated and shrinked the same way.

## Useful methods on the Arb module
## Useful methods on the Arb and ArbMap module

- `Arb.from<'a>` returns the registered Arbitrary instance for the given type 'a
- `Arb.fromGen` makes a new Arbitrary instance from just a given generator - the shrinker return the empty sequence
- `Arb.fromGenShrink` make a new Arbitrary instance from a given generator and shrinker. This is equivalent to implementing Arbitrary yourself, but may be shorter.
- `Arb.generate<'a>` returns the generator of the registered Arbitrary instance for the given type 'a
- `Arb.shrink` return the immediate shrinks of the registered Arbitrary instance for the given value
- `Arb.convert` given conversion functions to ('a ->'b) and from ('b ->'a), converts an Arbitrary<'a> instance to an Arbitrary<'b>
- `Arb.filter` filters the generator and shrinker for a given Arbitrary instance to contain only those values that match with the given filter function
- `Arb.mapFilter` maps the generator and filter the shrinkers for a given Arbitrary instance. Mapping the generator is sometimes faster, e.g. for a PositiveInt it is faster to take the absolute value than to filter the negative values.
- `Arb.Default` is a type that contains all the default Arbitrary instances as they are shipped and registerd by FsCheck by default. This is useful when you override a default generator - typically this is because you want to filter certain values from it, and then you need to be able to refer to the default generator in your overriding generator.*)
- `ArbMap.arbitrary<'a> arbMap` returns the Arbitrary instance in `arbMap` for the given type 'a
- `ArbMap.generate<'a> arbMap` returns the generator of the Arbitrary instance in `arbMap` for the given type 'a
- `ArbMap.defaults` is a map that provides access to all the default Arbitrary instances as they are shipped by FsCheck by default. This is useful when you override a default generator - typically this is because you want to filter certain values from it, and then you need to be able to refer to the default generator in your overriding generator.*)