diff --git a/test/server/validate.js b/test/server/validate.js
index bd028f71..724b6b87 100644
--- a/test/server/validate.js
+++ b/test/server/validate.js
@@ -1,7 +1,10 @@
 'use strict';
 
+const fs = require('fs');
+
 const test = require('tape');
-const sinon = require('sinon');
+const withDiff = require('../sinon-called-with-diff');
+const sinon = withDiff(require('sinon'));
 
 const before = require('../before');
 const dir = '../..';
@@ -35,6 +38,56 @@ test('validate: root: /', (t) => {
     t.end();
 });
 
+test('validate: root: /home', (t) => {
+    const fn = sinon.stub();
+    
+    validate.root('/home', (...args) => {
+        fn(...args);
+        
+        t.ok(fn.calledWith('root:', '/home'), 'should not call fn');
+        t.end();
+    });
+});
+
+test('validate: root: stat', (t) => {
+    const fn = sinon.stub();
+    const {stat} = fs;
+    
+    const error = 'ENOENT';
+    fs.stat = (dir, fn) => fn(Error(error));
+    
+    clean();
+    require(exitPath);
+    stub(exitPath, fn);
+    
+    const {root} = require(validatePath);
+    
+    root('hello', fn);
+    
+    const msg = 'cloudcmd --root: %s';
+    t.ok(fn.calledWith(msg, error), 'should call fn');
+    
+    fs.stat = stat;
+    t.end();
+});
+
+test('validate: packer: not valid', (t) => {
+    const fn = sinon.stub();
+    
+    clean();
+    require(exitPath);
+    stub(exitPath, fn);
+    
+    const {packer} = require(validatePath);
+    const msg = 'cloudcmd --packer: could be "tar" or "zip" only';
+    
+    packer('hello');
+    
+    t.ok(fn.calledWith(msg), 'should call fn');
+    
+    t.end();
+});
+
 test('validate: editor: not valid', (t) => {
     const fn = sinon.stub();
     
diff --git a/test/sinon-called-with-diff.js b/test/sinon-called-with-diff.js
new file mode 100644
index 00000000..5aca3e63
--- /dev/null
+++ b/test/sinon-called-with-diff.js
@@ -0,0 +1,57 @@
+'use strict';
+
+/* eslint-disable no-console */
+
+const chalk = require('chalk');
+
+module.exports = (sinon) => {
+    const {stub} = sinon;
+    
+    sinon.stub = () => {
+        const fn = stub();
+        const {calledWith:original} = fn;
+        
+        fn.calledWith = (...args) => {
+            if (original.apply(fn, args))
+                return true;
+            
+            return calledWith.apply(fn, args);
+        };
+        
+        return fn;
+    };
+    
+    Object.assign(sinon.stub, stub);
+    
+    return sinon;
+};
+
+function calledWith(...args) {
+    if (!this.called) {
+        write(`expected to call with ${JSON.stringify(this.args)}, but not called at all\n`);
+        return false;
+    }
+    
+    const actual = this.args.pop();
+    
+    write(`wrong arguments in ${this.func.name}`);
+    writeObjectActual('actual:', actual);
+    writeObjectExpected('expected:', args);
+    
+    return false;
+}
+
+function write(str) {
+    process.stdout.write(chalk.red(str) + '\n');
+}
+
+function writeObjectActual(str, object) {
+    const json = JSON.stringify(object, null, 2);
+    console.log(str, chalk.yellow(json) + '\n');
+}
+
+function writeObjectExpected(str, object) {
+    const json = JSON.stringify(object, null, 2);
+    console.log(str, chalk.green(json) + '\n');
+}
+