diff --git a/tests/solr_base_subquery.test b/tests/solr_base_subquery.test
index 36894ed..44f9493 100644
--- a/tests/solr_base_subquery.test
+++ b/tests/solr_base_subquery.test
@@ -113,6 +113,15 @@ class DrupalSolrFilterSubQueryTests extends DrupalUnitTestCase {
     $query2->addFilter('label', 'baz');
     $query1->addFilterSubQuery($query2);
     $params = $query1->getParam('fq');
-    $this->assertEqual($params[0], '-(label:bar AND label:baz)', '-(label:bar AND label:baz)');
+    $this->assertEqual($params[0], '-(label:bar AND label:baz)', t('The bar and baz label are excluded.'));
+
+    // Test if a field is either empty or has a certain value.
+    $query1 = $this->_apachesolr_drupal_query('DrupalTest');
+    $query2 = $this->_apachesolr_drupal_subquery('AND', TRUE);
+    $query2->addFilter('label', '*');
+    $query2->addFilter('label', 'bar', TRUE);
+    $query1->addFilterSubQuery($query2);
+    $params = $query1->getParam('fq');
+    $this->assertEqual($params[0], '-(label:* AND -label:bar)', t('The label should either be bar or empty.'));
   }
 }