Add coverage-helper to ignore validate tests in coverage

Cargo.toml

@@ -62,6 +62,7 @@ webbrowser = "0.8.10"
 urlencoding = "2.1.2"
 cool_asserts = "2.0.3"
 paste = "1.0"
+coverage-helper = "0.2.0"
 
 [[bench]]
 name = "bench_main"

src/hugr/validate/test.rs

@@ -1,4 +1,5 @@
 use cool_asserts::assert_matches;
+use coverage_helper::test;
 
 use super::*;
 use crate::builder::test::closed_dfg_root_hugr;

src/lib.rs

@@ -11,6 +11,9 @@
 // Unstable check, may cause false positives.
 // https://github.com/rust-lang/rust-clippy/issues/5112
 #![warn(clippy::debug_assert_with_mut_call)]
+// https://crates.io/crates/coverage-helper to allow selectively ignoring tests
+// in coverage.
+#![cfg_attr(coverage_nightly, feature(coverage_attribute))]
 
 pub mod algorithm;
 pub mod builder;