PHP return value detection

    /**
     * Foo mock factory
     *
     * @param string[] $methods [OPTIONAL] List of mocked method names
     * @return Foo|MockObject
     */
    protected function createFooMock(array $methods = []): MockObject
    {
        $mock = $this->createPartialMock(Foo::class, $methods);
        return $mock;
    }