[Refactor] _assert: avoid reassigning arguments

lib/test.js

@@ -450,7 +450,7 @@ Test.prototype._assert = function assert(ok, opts) {
 	var self = this;
 	var extra = opts.extra || {};
 
-	ok = !!ok || !!extra.skip;
+	var actualOK = !!ok || !!extra.skip;
 
 	var name = defined(extra.message, opts.message, '(unnamed assert)');
 	if (this.calledEnd && opts.operator !== 'fail') {
@@ -460,7 +460,7 @@ Test.prototype._assert = function assert(ok, opts) {
 
 	var res = {
 		id: self.assertCount++,
-		ok: ok,
+		ok: actualOK,
 		skip: defined(extra.skip, opts.skip),
 		todo: defined(extra.todo, opts.todo, self._todo),
 		name: name,
@@ -473,13 +473,13 @@ Test.prototype._assert = function assert(ok, opts) {
 	if (hasOwn(opts, 'expected') || hasOwn(extra, 'expected')) {
 		res.expected = defined(extra.expected, opts.expected);
 	}
-	this._ok = !!(this._ok && ok);
+	this._ok = !!(this._ok && actualOK);
 
-	if (!ok && !res.todo) {
+	if (!actualOK && !res.todo) {
 		res.error = defined(extra.error, opts.error, new Error(res.name));
 	}
 
-	if (!ok) {
+	if (!actualOK) {
 		var e = new Error('exception');
 		var err = $split(e.stack || '', '\n');
 		var tapeDir = __dirname + path.sep;