Update references to deprecated global

_config.php

@@ -12,7 +12,7 @@ TestSessionEnvironment::singleton()->loadFromFile();
  */
 if (class_exists('Resque_Event') && class_exists('SSResqueRun')) {
     Resque_Event::listen('beforeFork', function ($data) {
-		global $databaseConfig;
+        $databaseConfig = DB::getConfig();
 
         // Reconnect to the database - this may connect to the old DB first, but is required because these processes
         // are long-lived, and MySQL connections often get closed in between worker runs. We need to connect before

src/TestSessionEnvironment.php

@@ -450,9 +450,9 @@ class TestSessionEnvironment
     public function resetDatabaseName()
     {
         if ($this->oldDatabaseName) {
-            global $databaseConfig;
-
+            $databaseConfig = DB::getConfig();
             $databaseConfig['database'] = $this->oldDatabaseName;
+            DB::setConfig($databaseConfig);
 
             $conn = DB::get_conn();
 

src/TestSessionRequestFilter.php

@@ -58,7 +58,7 @@ class TestSessionRequestFilter implements RequestFilter
             $file = $testState->stubfile;
             if (!Director::isLive() && $file && file_exists($file)) {
                 // Connect to the database so the included code can interact with it
-                global $databaseConfig;
+                $databaseConfig = DB::getConfig();
                 if ($databaseConfig) {
                     DB::connect($databaseConfig);
                 }