pub fn triple_strategy() -> impl Strategy<Value = Option<String>> {
    let platform_strategy = Platform::filtered_strategy(
        |triple| {
            // Filter out Apple platforms because rustc requires the Apple SDKs to be set up for
            // them.
            !triple.contains("-apple-")
        },
        Just(TargetFeatures::Unknown),
    );
    prop_oneof![
        // 25% chance to generate None, 75% to generate a particular platform
        1 => Just(None),
        3 => platform_strategy.prop_map(|platform| Some(platform.triple_str().to_owned())),
    ]
}
Generates a random, known target triple that can be understood by both cargo and guppy, or
`None`.
guppy-cmdlib/src/proptest.rs