Fix tests

tests/TestCase/UnitTestTrait.php

@@ -38,8 +38,7 @@ protected function registerMock(string $class): void
         $container = $this->getContainer();
 
         if ($container instanceof Container) {
-            $definition = $container->extend($class);
-            $definition->setConcrete($this->createMockObject($class));
+            $container->add($class, $this->createMockObject($class));
         }
     }
 
@@ -59,21 +58,24 @@ protected function createMockObject(string $class): MockObject
             $methods[] = $method->name;
         }
 
-        return $this->getMockBuilder($class)->disableOriginalConstructor()->setMethods($methods)->getMock();
+        return $this->getMockBuilder($class)
+            ->disableOriginalConstructor()
+            ->setMethods($methods)
+            ->getMock();
     }
 
     /**
      * Create a mocked class method.
      *
      * @param array|callable $method The class and method
      *
-     * @return InvocationMocker The mocked method
+     * @return InvocationMocker
      */
     protected function mockMethod($method): InvocationMocker
     {
         /** @var MockObject $mock */
-        $mock = $this->getContainer()->get($method[0] ?? '');
+        $mock = $this->getContainer()->get((string)$method[0]);
 
-        return $mock->method($method[1] ?? '');
+        return $mock->method((string)$method[1]);
     }
 }