test: fix nits in test-fs-mkdir-rmdir.js

* Add common.mustCall().
* Add check for error existence, not only for error details.
* Use test(), not match() in a boolean context.
* Properly reverse meanings of assert messages.
PR-URL: #13680
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

Author: vsemozhetbyt

test/parallel/test-fs-mkdir-rmdir.js

@@ -24,14 +24,15 @@ fs.rmdirSync(d);
 assert(!common.fileExists(d));
 
 // Similarly test the Async version
-fs.mkdir(d,0o666,function(err){
+fs.mkdir(d,0o666,common.mustCall(function(err){
 assert.ifError(err);
 
-fs.mkdir(d,0o666,function(err){
-assert.ok(err.message.match(/^EEXIST/),'got EEXIST message');
-assert.strictEqual(err.code,'EEXIST','got EEXIST code');
-assert.strictEqual(err.path,d,'got proper path for EEXIST');
+fs.mkdir(d,0o666,common.mustCall(function(err){
+assert.ok(err,'got no error');
+assert.ok(/^EEXIST/.test(err.message),'got no EEXIST message');
+assert.strictEqual(err.code,'EEXIST','got no EEXIST code');
+assert.strictEqual(err.path,d,'got no proper path for EEXIST');
 
 fs.rmdir(d,assert.ifError);
-});
-});
+}));
+}));