Upgrade code with upgrader

.upgrade.yml

@@ -1,6 +1,7 @@
 mappings:
   TestSessionController: SilverStripe\TestSession\TestSessionController
   TestSessionEnvironment: SilverStripe\TestSession\TestSessionEnvironment
-  TestSessionRequestFilter: SilverStripe\TestSession\TestSessionRequestFilter
+  TestSessionRequestFilter: SilverStripe\TestSession\TestSessionHTTPMiddleware
   TestSessionStubCodeWriter: SilverStripe\TestSession\TestSessionStubCodeWriter
-  TestSessionStubCodeWriterTest: SilverStripe\TestSession\Tests\TestSessionStubCodeWriterTest
+excludedPaths:
+  - '*/testsession/_config/services.yml'

_config/routes.yml

@@ -3,4 +3,4 @@ Name: testsessionroutes
 ---
 SilverStripe\Control\Director:
   rules:
-    'dev/testsession': 'TestSessionController'
+    dev/testsession: SilverStripe\TestSession\TestSessionController

src/TestSessionEnvironment.php

@@ -12,6 +12,7 @@
 use SilverStripe\Core\Injector\Injectable;
 use SilverStripe\Core\Injector\Injector;
 use SilverStripe\Dev\FixtureFactory;
+use SilverStripe\Dev\YamlFixture;
 use SilverStripe\ORM\Connect\TempDatabase;
 use SilverStripe\ORM\DatabaseAdmin;
 use SilverStripe\ORM\DB;
@@ -433,8 +434,8 @@ public function loadFixtureIntoDb($fixtureFile)
             throw new LogicException("Fixture file must be inside the tests subfolder of one of your modules.");
         }
 
-        $factory = Injector::inst()->create('SilverStripe\\Dev\\FixtureFactory');
-        $fixture = Injector::inst()->create('SilverStripe\\Dev\\YamlFixture', $fixtureFile);
+        $factory = Injector::inst()->create(FixtureFactory::class);
+        $fixture = Injector::inst()->create(YamlFixture::class, $fixtureFile);
         $fixture->writeInto($factory);
 
         $state = $this->getState();