diff --git a/tests/Feature/CityTest.php b/tests/Feature/CityTest.php
index 2e351cd..3d727f3 100644
--- a/tests/Feature/CityTest.php
+++ b/tests/Feature/CityTest.php
@@ -4,36 +4,156 @@ namespace Tests\Feature;
 
 use Illuminate\Foundation\Testing\RefreshDatabase;
 use Illuminate\Foundation\Testing\WithFaker;
+use Illuminate\Foundation\Testing\DatabaseTransactions;
 use Tests\TestCase;
 
 use App\Models\City;
+use App\Models\Company;
+
+use function PHPUnit\Framework\assertNotNull;
 
 class CityTest extends TestCase
 {
-    /* City validation */
+    use DatabaseTransactions;
+
+    protected $city;
+    protected $company_ids = [];
 
-    public function test_city_with_empty_name(): void
+    public function setUpCityWithCompanies(): void
     {
-        $json = City::validate_with_name('');
+        $this->setUpCity();
+        $this->setUpCompanyIds();
 
-        $this->assertEquals($json['error'], 'The city name is empty, please, write the name!!!');
+        $this->city->addCompanyIds($this->company_ids);
     }
 
-    public function test_not_existing_city_with_name(): void
+    public function setUpCity(): void
     {
-        $name = '404 City';
+        $name = 'testCity';
+        $this->city = City::where('name', $name)->first();
+    }
 
-        $json = City::validate_with_name($name);
+    public function setUpCompanyIds(): void
+    {
+        $company_names = ['testCompany', 'testCompany2'];
+        $this->company_ids = [];
 
-        $this->assertEquals($json['error'], 'A city with the name does not exist!!!');
+        foreach($company_names as $name) {
+            $company = Company::where('name', $name)->first();
+            array_push($this->company_ids, $company->id);
+        }
     }
 
-    public function test_valid_city_with_name(): void
+    public function testGetCompaniesIdsForEmpty()
     {
-        $name = 'testCity';
+        $this->setUpCity();
+
+        $this->assertNotNull($this->city);
+        $this->assertIsArray($this->city->getCompanyIds());
+        $this->assertEquals($this->city->getCompanyIds(), []);
+    }
+
+    public function testAddCompaniesIdForTwoElements()
+    {
+        $this->setUpCity();
+        $this->setUpCompanyIds();
+
+        foreach($this->company_ids as $id)
+            $this->city->addCompanyId($id);
+
+        $this->assertNotNull($this->city);
+        $this->assertIsArray($this->city->getCompanyIds());
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
+    }
+
+    public function testAddNonExistingCompaniesId()
+    {
+        $this->setUpCityWithCompanies();
+
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
+
+        $this->city->AddCompanyId(23423);
+
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
+    }
+
+    public function testAddNonExistingCompaniesIdFromEmpty()
+    {
+        $this->setUpCity();
+        $this->company_ids = [];
+
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
+
+        $this->city->addCompanyId(23423);
+
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
+    }
+
+    public function testAddNonExistingCompaniesIdsFromEmpty()
+    {
+        $this->setUpCity();
+        $this->company_ids = [];
+
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
+
+        $this->city->addCompanyIds([23423, 1234]);
+
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
+    }
+
+    public function testRemoveCompaniesId()
+    {
+        $this->setUpCityWithCompanies();
+
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
+
+        $this->city->removeCompanyId($this->company_ids[1]);
+
+        $this->assertEquals($this->city->getCompanyIds(), [$this->company_ids[0]]);
+    }
+
+    public function testRemoveCompaniesIds()
+    {
+        $this->setUpCityWithCompanies();
+
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
+
+        $this->city->removeCompanyIds([$this->company_ids[1]]);
+
+        $this->assertEquals($this->city->getCompanyIds(), [$this->company_ids[0]]);
+    }
+
+    public function testRemoveCompaniesIdsForTwoElements()
+    {
+        $this->setUpCityWithCompanies();
+
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
+
+        $this->city->removeCompanyIds($this->company_ids);
+
+        $this->assertEquals($this->city->getCompanyIds(), []);
+    }
+
+    public function testRemoveNonExistingCompaniesIds()
+    {
+        $this->setUpCityWithCompanies();
+
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
+
+        $this->city->removeCompanyIds([23423, 1234]);
+
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
+    }
+
+    public function testRemoveNonExistingCompaniesIdsFromEmpty()
+    {
+        $this->setUpCity();
+        $this->company_ids = [];
+
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
 
-        $json = City::validate_with_name($name);
+        $this->city->removeCompanyIds([23423, 1234]);
 
-        $this->assertEquals($json['ok'], 'A city with the name is valid.');
+        $this->assertEquals($this->city->getCompanyIds(), $this->company_ids);
     }
 }