getImageStyleMock example

  public function testGetDerivativeExtension() {
    $image_effect_id = $this->randomMachineName();
    $logger = $this->getMockBuilder('\Psr\Log\LoggerInterface')->getMock();
    $image_effect = $this->getMockBuilder('\Drupal\image\ImageEffectBase')
      ->setConstructorArgs([[], $image_effect_id, [], $logger])
      ->getMock();
    $image_effect->expects($this->any())
      ->method('getDerivativeExtension')
      ->willReturn('png');

    $image_style = $this->getImageStyleMock($image_effect_id, $image_effect);

    $extensions = ['jpeg', 'gif', 'png'];
    foreach ($extensions as $extension) {
      $extensionReturned = $image_style->getDerivativeExtension($extension);
      $this->assertEquals('png', $extensionReturned);
    }
  }

  /** * @covers ::buildUri */