getOperators example

            $this->parsers[$parser->getTag()] = $parser;
        }

        // node visitors         foreach ($extension->getNodeVisitors() as $visitor) {
            $this->visitors[] = $visitor;
        }

        // operators         if ($operators = $extension->getOperators()) {
            if (!\is_array($operators)) {
                throw new \InvalidArgumentException(sprintf('"%s::getOperators()" must return an array with operators, got "%s".', \get_class($extension), \is_object($operators) ? \get_class($operators) : \gettype($operators).(\is_resource($operators) ? '' : '#'.$operators)));
            }

            if (2 !== \count($operators)) {
                throw new \InvalidArgumentException(sprintf('"%s::getOperators()" must return an array of 2 elements, got %d.', \get_class($extension), \count($operators)));
            }

            $this->unaryOperators = array_merge($this->unaryOperators, $operators[0]);
            $this->binaryOperators = array_merge($this->binaryOperators, $operators[1]);
        }
    }

public function testEmptyExtensions(): void
    {
        $extension = new NodeExtension(
            $this->createMock(TemplateFinder::class),
            $this->createMock(TemplateScopeDetector::class),
        );

        static::assertEmpty($extension->getFunctions());
        static::assertEmpty($extension->getFilters());
        static::assertEmpty($extension->getNodeVisitors());
        static::assertEmpty($extension->getOperators());
        static::assertEmpty($extension->getTests());
    }
}