pub fn num_proptests(&self) -> u32 {
        // Large graphs (like cargo-guppy's) can only really do a tiny number of proptests
        // reasonably in debug mode. It would be cool to figure out a way to speed it up (release
        // mode works -- also maybe through parallelization?)
        static PROPTEST_MULTIPLIER: Lazy<u32> =
            Lazy::new(|| match env::var("PROPTEST_MULTIPLIER") {
                Ok(multiplier) => multiplier
                    .parse()
                    .expect("PROPTEST_MULTIPLIER is a valid u32"),
                Err(_) => 2,
            });
        if self.graph.package_count() > 100 {
            *PROPTEST_MULTIPLIER
        } else {
            *PROPTEST_MULTIPLIER * 4
        }
    }
Returns the number of proptest iterations that should be run for this fixture.
internal-tools/cargo-compare/src/tests/fixtures.rs