Function compare_tests 

pub fn compare_tests(
    source: &str,
    candidates: &[PageTierKind],
    suite_seed: u64,
    budget: u64,
    launcher: Option<&dyn RemotePageLauncher>,
) -> Result<Vec<TestTierComparison>, String>

Parse source, and run every ## Test in it that works a page on the reference tier and on each of candidates. A test whose program mounts nothing is not a page scenario and is left out. ## Main is the program’s entry point, never test fixture, and is stripped as the test runner strips it.