EelStandaloneDemonstrationTest.php

<?php
namespace Acme\Package\Tests\Functional;

use TYPO3\Flow\Annotations as Flow;
use TYPO3\Flow\Configuration\ConfigurationManager;
use TYPO3\Flow\Tests\FunctionalTestCase;
use TYPO3\Eel\Utility as EelUtility;

/**
 * Designed as a functional test, should offer every information you need to get started.
 */
class EelStandaloneDemonstrationTest extends FunctionalTestCase {

	/**
	* @var \TYPO3\Eel\EelEvaluatorInterface
	*/
	protected $eelEvaluator;

	/**
	* @var array
	*/
	protected $defaultContextVariables = array();

	/**
	*/
	public function setUp() {
		parent::setUp();
		$this->eelEvaluator = $this->objectManager->get('TYPO3\Eel\EelEvaluatorInterface');

		/** @var ConfigurationManager $configurationManager */
		$configurationManager = $this->objectManager->get('TYPO3\Flow\Configuration\ConfigurationManager');
		$this->defaultContextVariables = $configurationManager->getConfiguration(
		                                                                        'Settings',
		                                                                        'Acme.Package.defaultEelContextVariables');
	}

	/**
	* Data provider
	* Signature: Eel expression, expected evaluation result, context variables
	*/
	public function eelEvaluationDataProvider() {
		return array(
			array('${18 + 4 / 2}',       20),
			array('${foo * foo + 2}',    11, array('foo' => 3)),
			array('${Math.pow(bar, 3)}', 64, array('bar' => 4))
		);
	}

	/**
	* @param string $expression
	* @param mixed $expectedEvaluation
	* @param array $contextVariables
	* @dataProvider eelEvaluationDataProvider
	* @test
	*/
	public function eelExpressionsAreCorrectlyEvaluated($expression, $expectedEvaluation, $contextVariables = array()) {
		$actualEvaluation = EelUtility::evaluateEelExpression(
		                                                     $expression,
		                                                     $this->eelEvaluator,
		                                                     $contextVariables,
		                                                     $this->defaultContextVariables);

		$this->assertEquals($expectedEvaluation, $actualEvaluation);
	}

}

Settings.yaml

Acme:
  Package:

    defaultEelContextVariables:
      String: 'TYPO3\Eel\Helper\StringHelper'
      Array: 'TYPO3\Eel\Helper\ArrayHelper'
      Date: 'TYPO3\Eel\Helper\DateHelper'
      Configuration: 'TYPO3\Eel\Helper\ConfigurationHelper'
      Math: 'TYPO3\Eel\Helper\MathHelper'
      Json: 'TYPO3\Eel\Helper\JsonHelper'