test: display better error message for assertion

This commit makes understanding assertion failures easier by
displaying the values that failed the assertion.

PR-URL: #15883
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: Michaël Zasso <[email protected]>

Author: SgtPooki

test/parallel/test-zlib-random-byte-pipes.js

@@ -129,5 +129,5 @@ const gunz = zlib.createGunzip();
 inp.pipe(gzip).pipe(gunz).pipe(out);
 
 out.on('data', common.mustCall((c) => {
-  assert.strictEqual(c, inp._hash, 'hashes should match');
+  assert.strictEqual(c, inp._hash, `Hash '${c}' equals '${inp._hash}'.`);
 }));