[v6.x backport] assert: refactor the code

[BridgeAR]

Ref #13862

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

assert

[BridgeAR]

@MylesBorins we have a linter error on v6.x-staging

diff --git a/test/parallel/test-fs-readfile-unlink.js b/test/parallel/test-fs-readfile-unlink.js
index aa17324963..203ea681e5 100644
--- a/test/parallel/test-fs-readfile-unlink.js
+++ b/test/parallel/test-fs-readfile-unlink.js
@@ -3,7 +3,6 @@ const common = require('../common');
 const assert = require('assert');
 const fs = require('fs');
 const path = require('path');
-const dirName = path.resolve(common.fixturesDir, 'test-readfile-unlink');
 const fileName = path.resolve(common.tmpDir, 'test.bin');
 
 const buf = Buffer.alloc(512 * 1024, 42);

I am not sure how we should fix that. Should I just open a new PR against the branch?

[MylesBorins]

@BridgeAR I fixed this in the staging branch. give it another rebase 😄

[BridgeAR]

@MylesBorins rebased

[MylesBorins]

landed in 55a2bd2...a8b34d8