test: increase coverage for internal/module.js

PR-URL: https://github.com/nodejs/node/pull/13673
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-internal-modules-strip-shebang.js

@@ -0,0 +1,14 @@
+// Flags: --expose-internals
+'use strict';
+require('../common');
+
+const assert = require('assert');
+const stripShebang = require('internal/module').stripShebang;
+
+[
+  ['', ''],
+  ['aa', 'aa'],
+  ['#!', ''],
+  ['#!bin/bash', ''],
+  ['#!bin/bash\naa', '\naa'],
+].forEach((i) => assert.strictEqual(stripShebang(i[0]), i[1]));