diff --git a/src/Annotation/FacetsUrlProcessor.php b/src/Annotation/FacetsUrlProcessor.php
index 1075384..8547812 100644
--- a/src/Annotation/FacetsUrlProcessor.php
+++ b/src/Annotation/FacetsUrlProcessor.php
@@ -1,7 +1,7 @@
 <?php
 /**
  * @file
- * Contains \Drupal\facets\Annotation\FacetsProcessor.
+ * Contains \Drupal\facets\Annotation\FacetsUrlProcessor.
  */
 
 namespace Drupal\facets\Annotation;
diff --git a/src/Plugin/facets/processor/UrlProcessorHandler.php b/src/Plugin/facets/processor/UrlProcessorHandler.php
index 1852a15..3ec3819 100644
--- a/src/Plugin/facets/processor/UrlProcessorHandler.php
+++ b/src/Plugin/facets/processor/UrlProcessorHandler.php
@@ -42,7 +42,7 @@ class UrlProcessorHandler extends ProcessorPluginBase implements BuildProcessorI
   public function __construct(array $configuration, $plugin_id, array $plugin_definition) {
     parent::__construct($configuration, $plugin_id, $plugin_definition);
 
-    if (!isset($configuration['facet'])) {
+    if (!isset($configuration['facet']) || !$configuration['facet'] instanceof FacetInterface) {
       throw new InvalidProcessorException("The UrlProcessorHandler doesn't have the required 'facet' in the configuration array.");
     }
 
diff --git a/tests/src/Unit/Plugin/processor/UrlProcessorHandlerTest.php b/tests/src/Unit/Plugin/processor/UrlProcessorHandlerTest.php
new file mode 100644
index 0000000..c411be8
--- /dev/null
+++ b/tests/src/Unit/Plugin/processor/UrlProcessorHandlerTest.php
@@ -0,0 +1,80 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\facets\Plugin\url_processor\QueryStringTest.
+ */
+
+namespace Drupal\Tests\facets\Unit\Plugin\processor;
+
+use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\facets\Entity\Facet;
+use Drupal\facets\Plugin\facets\processor\UrlProcessorHandler;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * Unit test for processor.
+ *
+ * @group facets
+ */
+class UrlProcessorHandlerTest extends UnitTestCase {
+
+  /**
+   * Tests that the processor correctly throws an exception.
+   */
+  public function testEmptyProcessorConfiguration() {
+    $this->setExpectedException('\Drupal\facets\Exception\InvalidProcessorException', "The UrlProcessorHandler doesn't have the required 'facet' in the configuration array.");
+    new UrlProcessorHandler([], 'test', []);
+  }
+
+  /**
+   * Tests that the processor correctly throws an exception.
+   */
+  public function testInvalidProcessorConfiguration() {
+    $this->setExpectedException('\Drupal\facets\Exception\InvalidProcessorException', "The UrlProcessorHandler doesn't have the required 'facet' in the configuration array.");
+    new UrlProcessorHandler(['facet' => new \stdClass()], 'test', []);
+  }
+
+  /**
+   * Test that the build method is correctly called.
+   */
+  public function testBuild() {
+    $facet = new Facet(['id' => '_test'], 'facets_facet');
+    $this->createContainer();
+
+    $processor = new UrlProcessorHandler(['facet' => $facet], 'url_processor_handler', []);
+    // The actual results of this should be tested in the actual processor.
+    $processor->build($facet, []);
+  }
+
+  /**
+   * Helper function to create a correct container.
+   */
+  protected function createContainer() {
+    $url_processor = $this->getMockBuilder('\Drupal\facets\UrlProcessor\UrlProcessorInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+
+    $manager = $this->getMockBuilder('\Drupal\facets\FacetSource\FacetSourcePluginManager')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $manager->expects($this->exactly(1))
+      ->method('createInstance')
+      ->willReturn($url_processor);
+
+    $storage = $this->getMock('\Drupal\Core\Entity\EntityStorageInterface');
+    $em = $this->getMockBuilder('\Drupal\Core\Entity\EntityTypeManagerInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $em->expects($this->exactly(2))
+      ->method('getStorage')
+      ->willReturn($storage);
+
+    $container = new ContainerBuilder();
+    $container->set('entity.manager', $em);
+    $container->set('entity_type.manager', $em);
+    $container->set('plugin.manager.facets.url_processor', $manager);
+    \Drupal::setContainer($container);
+  }
+
+}
diff --git a/tests/src/Unit/Plugin/url_processor/QueryStringUrlProcessorTest.php b/tests/src/Unit/Plugin/url_processor/QueryStringTest.php
similarity index 100%
rename from tests/src/Unit/Plugin/url_processor/QueryStringUrlProcessorTest.php
rename to tests/src/Unit/Plugin/url_processor/QueryStringTest.php