[Bugfix] Fix the FacetsManager modifying non-main queries

CHANGELOG.md

@@ -6,6 +6,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ## [Unreleased]
 
+### Fixed
+
+- Fix facets applying on non-main queries ([#49](https://github.com/studiometa/wp-toolkit/issues/49), [#50](https://github.com/studiometa/wp-toolkit/pull/50), [9c098c7](https://github.com/studiometa/wp-toolkit/commit/9c098c7))
+
 ## v2.3.0 - 2024.08.14
 
 ### Added

src/Managers/FacetsManager.php

@@ -58,7 +58,7 @@ public function run()
      */
     public function add_facets_to_query(WP_Query &$query): void
     {
-        if (!is_array($this->facets)) {
+        if (!is_array($this->facets) || !$query->is_main_query()) {
             return;
         }
 

tests/Managers/FacetsManagerTest.php

@@ -210,4 +210,21 @@ public function test_it_should_handle_array_values_in_facets()
         $this->assertEquals(['slug1', 'slug2'], $tax_query[0]['terms']);
         $this->assertEquals('slug', $tax_query[0]['field']);
     }
+
+    public function test_it_should_not_add_facets_to_non_main_query()
+    {
+        request()->query->set('facets', ['cat' => 1]);
+        $manager = new FacetsManager();
+        $manager->run();
+
+        // Create a non-main query
+        $secondary_query = new WP_Query();
+        $secondary_query->init();
+
+        // Manually call the method to simulate what happens on pre_get_posts
+        $manager->add_facets_to_query($secondary_query);
+
+        // The facets should not be applied to the secondary query
+        $this->assertFalse(isset($secondary_query->query_vars['cat']));
+    }
 }