Nelmio\Alice\Generator\Resolver\ResolvingContext::has PHP Method

    public function has(string $key) : bool
    {
        return array_key_exists($key, $this->resolving);
    }

 public function testMutator()
 {
     $context = new ResolvingContext();
     $this->assertFalse($context->has('foo'));
     $context->add('foo');
     $this->assertTrue($context->has('foo'));
 }