diff --git a/Build/Test/bootstrap.sh b/Build/Test/bootstrap.sh
index b058fa5ef1..5f098935d7 100755
--- a/Build/Test/bootstrap.sh
+++ b/Build/Test/bootstrap.sh
@@ -91,23 +91,7 @@ echo "Using extension path $EXTENSION_ROOTPATH"
 echo "Using package path $TYPO3_PATH_PACKAGES"
 echo "Using web path $TYPO3_PATH_WEB"
 
-# Install TYPO3 sources
-if [[ $TYPO3_VERSION = *"main"* ]]; then
-  composer config minimum-stability dev
-fi
-
-if ! composer require --dev --update-with-dependencies --prefer-source \
-  typo3/cms-core:"$TYPO3_VERSION" \
-  typo3/cms-backend:"$TYPO3_VERSION" \
-  typo3/cms-recordlist:"$TYPO3_VERSION" \
-  typo3/cms-fluid:"$TYPO3_VERSION" \
-  typo3/cms-fluid-styled-content:"$TYPO3_VERSION" \
-  typo3/cms-frontend:"$TYPO3_VERSION" \
-  typo3/cms-extbase:"$TYPO3_VERSION" \
-  typo3/cms-reports:"$TYPO3_VERSION" \
-  typo3/cms-scheduler:"$TYPO3_VERSION" \
-  typo3/cms-tstemplate:"$TYPO3_VERSION" \
-  typo3/cms-install:"$TYPO3_VERSION"
+if ! composer tests:setup
 then
   echo "The test environment could not be installed by composer as expected. Please fix this issue."
   exit 1
diff --git a/Build/Test/cibuild.sh b/Build/Test/cibuild.sh
index f8840ffa32..a3a7f6ddab 100755
--- a/Build/Test/cibuild.sh
+++ b/Build/Test/cibuild.sh
@@ -43,7 +43,7 @@ else
     echo "Some files are not compliant to TYPO3 Coding Standards"
     echo "Please fix the files listed above."
     echo "Tip for auto fix: "
-    echo "  composer install && composer exec php-cs-fixer fix"
+    echo "  TYPO3_VERSION="${TYPO3_VERSION}" composer tests:setup && composer t3:standards:fix"
     exit 1
   else
     echo "The code is TYPO3 Coding Standards compliant! Great job!"
diff --git a/Classes/ViewHelpers/TranslateViewHelper.php b/Classes/ViewHelpers/TranslateViewHelper.php
index ca87657e3e..2ffc05a347 100644
--- a/Classes/ViewHelpers/TranslateViewHelper.php
+++ b/Classes/ViewHelpers/TranslateViewHelper.php
@@ -42,7 +42,6 @@ class TranslateViewHelper extends AbstractViewHelper
      * Register required keys for translation
      *
      * @see \TYPO3\CMS\Fluid\ViewHelpers\TranslateViewHelper::initializeArguments
-     * @return void
      */
     public function initializeArguments(): void
     {
diff --git a/Tests/Integration/GarbageCollectorTest.php b/Tests/Integration/GarbageCollectorTest.php
index c0e97047fa..bc37c6b125 100644
--- a/Tests/Integration/GarbageCollectorTest.php
+++ b/Tests/Integration/GarbageCollectorTest.php
@@ -41,7 +41,7 @@ class GarbageCollectorTest extends IntegrationTest
     /**
      * @var array
      */
-    protected $coreExtensionsToLoad = [
+    protected array $coreExtensionsToLoad = [
         'extensionmanager',
         'scheduler',
     ];
diff --git a/Tests/Integration/IndexQueue/RecordMonitorTest.php b/Tests/Integration/IndexQueue/RecordMonitorTest.php
index 1acae208b7..015530ed71 100644
--- a/Tests/Integration/IndexQueue/RecordMonitorTest.php
+++ b/Tests/Integration/IndexQueue/RecordMonitorTest.php
@@ -46,7 +46,7 @@ class RecordMonitorTest extends IntegrationTest
     /**
      * @var array
      */
-    protected $coreExtensionsToLoad = [
+    protected array $coreExtensionsToLoad = [
         'extensionmanager',
         'scheduler',
     ];
diff --git a/Tests/Integration/IntegrationTest.php b/Tests/Integration/IntegrationTest.php
index 80e2dcbe88..91417ff3b5 100644
--- a/Tests/Integration/IntegrationTest.php
+++ b/Tests/Integration/IntegrationTest.php
@@ -64,7 +64,7 @@ abstract class IntegrationTest extends FunctionalTestCase
 {
     use SiteBasedTestTrait;
 
-    protected $coreExtensionsToLoad = [
+    protected array $coreExtensionsToLoad = [
         'scheduler',
         'fluid_styled_content',
     ];
@@ -81,7 +81,7 @@ abstract class IntegrationTest extends FunctionalTestCase
     /**
      * @var array
      */
-    protected $testExtensionsToLoad = [
+    protected array $testExtensionsToLoad = [
         'typo3conf/ext/solr',
     ];
 
@@ -97,17 +97,12 @@ abstract class IntegrationTest extends FunctionalTestCase
     /**
      * @var array
      */
-    protected $configurationToUseInTestInstance = [
+    protected array $configurationToUseInTestInstance = [
        'SYS' =>  [
            'exceptionalErrors' =>  E_WARNING | E_RECOVERABLE_ERROR | E_DEPRECATED | E_USER_DEPRECATED,
        ],
     ];
 
-    /**
-     * @var string
-     */
-    protected $instancePath;
-
     /**
      * If set to true in subclasses, the import of configured root pages will be skipped.
      *
diff --git a/Tests/Integration/Task/EventQueueWorkerTaskTest.php b/Tests/Integration/Task/EventQueueWorkerTaskTest.php
index b78d7aae4d..2b6a3e3e31 100644
--- a/Tests/Integration/Task/EventQueueWorkerTaskTest.php
+++ b/Tests/Integration/Task/EventQueueWorkerTaskTest.php
@@ -35,7 +35,7 @@ class EventQueueWorkerTaskTest extends IntegrationTest
     /**
      * @var array
      */
-    protected $coreExtensionsToLoad = [
+    protected array $coreExtensionsToLoad = [
         'extensionmanager',
         'scheduler',
     ];
diff --git a/Tests/Integration/Task/IndexQueueWorkerTaskTest.php b/Tests/Integration/Task/IndexQueueWorkerTaskTest.php
index 2fbe2b3ee3..4325a2fa7d 100644
--- a/Tests/Integration/Task/IndexQueueWorkerTaskTest.php
+++ b/Tests/Integration/Task/IndexQueueWorkerTaskTest.php
@@ -43,7 +43,7 @@ class IndexQueueWorkerTaskTest extends IntegrationTest
     /**
      * @var array
      */
-    protected $coreExtensionsToLoad = [
+    protected array $coreExtensionsToLoad = [
         'scheduler',
     ];
 
diff --git a/Tests/Integration/Task/ReIndexTaskTest.php b/Tests/Integration/Task/ReIndexTaskTest.php
index ee3bb75e0d..8f530983bd 100644
--- a/Tests/Integration/Task/ReIndexTaskTest.php
+++ b/Tests/Integration/Task/ReIndexTaskTest.php
@@ -52,7 +52,7 @@ class ReIndexTaskTest extends IntegrationTest
     /**
      * @var array
      */
-    protected $coreExtensionsToLoad = [
+    protected array $coreExtensionsToLoad = [
         'scheduler',
     ];
 
diff --git a/Tests/Unit/UnitTest.php b/Tests/Unit/UnitTest.php
index 4612bd48b7..841ee3b3b0 100644
--- a/Tests/Unit/UnitTest.php
+++ b/Tests/Unit/UnitTest.php
@@ -27,7 +27,7 @@
  */
 abstract class UnitTest extends UnitTestCase
 {
-    protected $resetSingletonInstances = true;
+    protected bool $resetSingletonInstances = true;
 
     protected function setUp(): void
     {
diff --git a/composer.json b/composer.json
index bf6052666e..98549d5511 100644
--- a/composer.json
+++ b/composer.json
@@ -21,14 +21,14 @@
     "docs": "https://docs.typo3.org/p/apache-solr-for-typo3/solr/main/en-us/"
   },
   "require": {
-    "php": "^7.4.0 || ^8.0",
+    "php": "^8.1",
     "ext-dom": "*",
     "ext-json": "*",
     "ext-libxml": "*",
     "ext-simplexml": "*",
     "solarium/solarium": "6.2.7",
     "typo3/cms-backend": "*",
-    "typo3/cms-core": "^12.0.0 || dev-main",
+    "typo3/cms-core": "^12",
     "typo3/cms-extbase": "*",
     "typo3/cms-fluid": "*",
     "typo3/cms-frontend": "*",
@@ -40,7 +40,7 @@
     "typo3/coding-standards": ">=0.5.0",
     "phpunit/phpunit": "^9.5",
     "phpspec/prophecy-phpunit":"*",
-    "typo3/testing-framework": "^6.12",
+    "typo3/testing-framework": "dev-main",
     "typo3/cms-fluid-styled-content": "*",
     "scrutinizer/ocular": "*",
     "sclable/xml-lint": "*"
@@ -58,7 +58,7 @@
   "autoload-dev": {
     "psr-4": {
       "ApacheSolrForTypo3\\Solr\\Tests\\": "Tests/",
-      "TYPO3\\CMS\\Core\\Tests\\": ".Build/Web/typo3/sysext/core/Tests/"
+      "TYPO3\\CMS\\Core\\Tests\\": ".Build/Web/vendor/typo3/cms-core/Tests/"
     }
   },
   "minimum-stability": "stable",
@@ -82,7 +82,7 @@
     "tests:restore-git": "echo \"Retore composer.json to initial state:\" && git checkout composer.json",
     "tests:env": [
       "if [ -z ${TYPO3_VERSION+x} ]; then >&2 echo \"Can not proceed, because env var TYPO3_VERSION is not set\"; exit 1; else echo \"Setup test environment for TYPO3 ${TYPO3_VERSION}\"; fi",
-      "if [ \"${TYPO3_VERSION#*dev}\" != \"dev\" ]; then $COMPOSER_BINARY config minimum-stability dev; fi"
+      "if [ $(echo $TYPO3_VERSION | grep -c dev) -eq 1 ]; then $COMPOSER_BINARY config minimum-stability dev; fi"
     ],
     "tests:setup": [
       "@tests:env",