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rustproperty-based-testingproptest

How do I create a Strategy that generates a value in a given range in proptest?

I want to create a Strategy that generates u32 values less than 1000000 efficiently and uniformly. The only two ways that I know to do this are to use any::<u32>() and then do one of the following:

  • use prop_filter to filter out values greater than or equal to 1000000
  • use prop_map to convert the values greater than or equal to 1000000 to values less than 1000000 using the modulus operator (i.e. .prop_map(|x|x % 1000000)). However, this would not provide a uniform sample, and it seems a bit clunky.

Is there any better way to do this, perhaps by using proptest::prelude::Rng::gen_range() somehow?

Solution

  • Just use a Range, as their tutorial states:

    0..100i32 is a strategy to generate i32s between 0, inclusive, and 100, exclusive

    so the strategy for numbers up to 1_000_000 is 0u32..1_000_000