Ticket #36227: 36227.diff

src/wp-includes/category.php

@@ -51 +51 @@
                 $taxonomy = $args['taxonomy'] = 'link_category';
         }
 
-        $categories = (array) get_terms( $taxonomy, $args );
+        $categories = get_terms( $taxonomy, $args );
 
-        foreach ( array_keys( $categories ) as $k )
-                _make_cat_compat( $categories[$k] );
+        if ( is_wp_error( $categories ) ) {
+                $categories = array();
+        } else {
+                $categories = (array) $categories;
+                foreach ( array_keys( $categories ) as $k ) {
+                        _make_cat_compat( $categories[ $k ] );
+                }
+        }
 
         return $categories;
 }

new file tests/phpunit/tests/category/getCategories.php

@@ +1 @@
+<?php
+
+/**
+ * @group taxonomy
+ * @group category.php
+ */
+class Tests_Category_GetCategories extends WP_UnitTestCase {
+        /**
+         * @ticket 36227
+         */
+        public function test_wp_error_should_return_an_empty_array() {
+                $found = get_categories( array( 'taxonomy' => 'foo' ) );
+                $this->assertSame( array(), $found );
+        }
+}