Set default

settings/Controller/SecuritySettingsController.php

@@ -61,7 +61,7 @@ class SecuritySettingsController extends Controller {
 	 * @return array
 	 */
 	public function trustedDomains($newTrustedDomain) {
-		$trustedDomains = $this->config->getSystemValue('trusted_domains');
+		$trustedDomains = $this->config->getSystemValue('trusted_domains', []);
 		$trustedDomains[] = $newTrustedDomain;
 		$this->config->setSystemValue('trusted_domains', $trustedDomains);
 

tests/Settings/Controller/SecuritySettingsControllerTest.php

@@ -57,8 +57,8 @@ class SecuritySettingsControllerTest extends \PHPUnit_Framework_TestCase {
 		$this->container['Config']
 			->expects($this->once())
 			->method('getSystemValue')
-			->with('trusted_domains')
-			->will($this->returnValue(''));
+			->with($this->equalTo('trusted_domains'), $this->equalTo([]))
+			->willReturn([]);
 
 		$response = $this->securitySettingsController->trustedDomains('newdomain.com');
 		$expectedResponse = array('status' => 'success');