83 lines
2.1 KiB
Rust
83 lines
2.1 KiB
Rust
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//! This module implements manually tracked test coverage, which useful for
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//! quickly finding a test responsible for testing a particular bit of code.
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//!
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//! See https://matklad.github.io/2018/06/18/a-trick-for-test-maintenance.html
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//! for details, but the TL;DR is that you write your test as
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//!
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//! ```no-run
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//! #[test]
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//! fn test_foo() {
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//! covers!(test_foo);
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//! }
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//! ```
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//!
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//! and in the code under test you write
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//!
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//! ```no-run
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//! fn foo() {
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//! if some_condition() {
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//! tested_by!(test_foo);
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//! }
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//! }
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//! ```
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//!
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//! This module then checks that executing the test indeed covers the specified
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//! function. This is useful if you come back to the `foo` function ten years
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//! later and wonder where the test are: now you can grep for `test_foo`.
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#[macro_export]
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macro_rules! tested_by {
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($ident:ident) => {
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#[cfg(test)]
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{
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crate::marks::marks::$ident.fetch_add(1, std::sync::atomic::Ordering::SeqCst);
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}
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};
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}
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#[macro_export]
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macro_rules! covers {
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($ident:ident) => {
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let _checker = crate::marks::marks::MarkChecker::new(&crate::marks::marks::$ident);
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};
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}
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#[cfg(test)]
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pub(crate) mod marks {
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use std::sync::atomic::{AtomicUsize, Ordering};
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pub(crate) struct MarkChecker {
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mark: &'static AtomicUsize,
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value_on_entry: usize,
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}
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impl MarkChecker {
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pub(crate) fn new(mark: &'static AtomicUsize) -> MarkChecker {
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let value_on_entry = mark.load(Ordering::SeqCst);
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MarkChecker {
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mark,
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value_on_entry,
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}
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}
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}
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impl Drop for MarkChecker {
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fn drop(&mut self) {
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if std::thread::panicking() {
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return;
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}
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let value_on_exit = self.mark.load(Ordering::SeqCst);
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assert!(value_on_exit > self.value_on_entry, "mark was not hit")
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}
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}
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macro_rules! mark {
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($ident:ident) => {
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#[allow(bad_style)]
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pub(crate) static $ident: AtomicUsize = AtomicUsize::new(0);
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};
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}
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mark!(name_res_works_for_broken_modules);
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}
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