Add tests for the City and User validations.

tests/Feature/UserTest.php

@@ -2,10 +2,13 @@
 
 namespace Tests\Feature;
 
+use App\Http\Controllers\API\v2\UserController;
 use Illuminate\Foundation\Testing\RefreshDatabase;
 use Illuminate\Foundation\Testing\WithFaker;
 use Tests\TestCase;
 
+use Illuminate\Http\Request;
+
 use App\Models\User;
 
 class UserTest extends TestCase
@@ -87,4 +90,31 @@ class UserTest extends TestCase
             'username' => $this->username
         ]);
     }
+
+    /* User validation */
+
+    public function test_empty_username_with_matrix_username(): void
+    {
+        $json = User::validate_with_matrix_username('');
+
+        $this->assertEquals($json['error'], 'The username is empty, please, write username!!!');
+    }
+
+    public function test_not_existing_user_with_matrix_username(): void
+    {
+        $matrix_username = '@kostia:test.com';
+
+        $json = User::validate_with_matrix_username($matrix_username);
+
+        $this->assertEquals($json['error'], 'A user with the username does not exist!!!');
+    }
+
+    public function test_valid_user_with_matrix_username(): void
+    {
+        $matrix_username = '@test:test.com';
+
+        $json = User::validate_with_matrix_username($matrix_username);
+
+        $this->assertEquals($json['ok'], 'A user with the username is valid.');
+    }
 }