Merge 5d14e87748 into 097313b0f1

src/TestSessionEnvironment.php

@@ -570,14 +570,14 @@ class TestSessionEnvironment
                 }
 
                 // Connect to database
-                DB::connect($databaseConfig);
+                $this->connectToDB($databaseConfig);
             } else {
                 // We've already connected to the database, do a fast check to see what database we're currently using
                 $db = DB::get_conn()->getSelectedDatabase();
                 if (isset($state->database) && $db != $state->database) {
                     $this->oldDatabaseName = $databaseConfig['database'];
                     $databaseConfig['database'] = $state->database;
-                    DB::connect($databaseConfig);
+                    $this->connectToDB($databaseConfig);
                 }
             }
         }
@@ -613,4 +613,15 @@ class TestSessionEnvironment
 
         return true;
     }
+
+    private function connectToDB(array $databaseConfig): void
+    {
+        if (method_exists(DB::class, 'hasConfig') && DB::hasConfig('primary')) {
+            // CMS 5.4+ - ensure we connect the primary connection and not a replica
+            DB::connect($databaseConfig, 'primary');
+        } else {
+            // CMS 5.3 and below do not support replica connections
+            DB::connect($databaseConfig);
+        }
+    }
 }