tests: Don't treat tests as code-under-test

This influences code coverage results and has no other effect.

Author: jan-ferdinand

twenty-first/src/tip5/inverse.rs

@@ -111,6 +111,7 @@ impl InverseTip5 {
 }
 
 #[cfg(test)]
+#[cfg_attr(coverage_nightly, coverage(off))]
 mod tests {
     use proptest::prelude::*;
 

twenty-first/src/tip5/mod.rs

@@ -40,9 +40,13 @@ pub mod digest;
     target_feature = "avx512vbmi"
 ))]
 mod avx512;
+
 #[cfg(test)]
+#[cfg_attr(coverage_nightly, coverage(off))]
 mod inverse;
+
 #[cfg(test)]
+#[cfg_attr(coverage_nightly, coverage(off))]
 mod naive;
 
 /// The lookup table with a high algebraic degree used in the TIP-5 permutation. To verify its

twenty-first/src/tip5/naive.rs

@@ -82,6 +82,7 @@ impl PartialEq<Tip5> for NaiveTip5 {
 }
 
 #[cfg(test)]
+#[cfg_attr(coverage_nightly, coverage(off))]
 mod tests {
     use proptest::prelude::*;