diff --git a/composer.json b/composer.json
index 8b6faad2..62e89e4a 100644
--- a/composer.json
+++ b/composer.json
@@ -26,9 +26,8 @@
         "league/flysystem": "^1.0.70"
     },
     "require-dev": {
+        "silverstripe/recipe-testing": "dev-two",
         "silverstripe/versioned": "^1@dev",
-        "sminnee/phpunit-mock-objects": "^3.4.5",
-        "sminnee/phpunit": "^5.7.29",
         "squizlabs/php_codesniffer": "^3",
         "mikey179/vfsstream": "^1.6"
     },
diff --git a/tests/php/AssetControlExtensionTest.php b/tests/php/AssetControlExtensionTest.php
index cc12f376..9608f509 100644
--- a/tests/php/AssetControlExtensionTest.php
+++ b/tests/php/AssetControlExtensionTest.php
@@ -25,7 +25,7 @@ class AssetControlExtensionTest extends SapphireTest
         TestObject::class
     ];
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -55,7 +55,7 @@ public function setUp()
         $object3->publishSingle();
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
@@ -224,7 +224,7 @@ public function testReplaceFile()
         $this->assertEquals(AssetStore::VISIBILITY_PUBLIC, $object3->Header->getVisibility());
     }
 
-    
+
     public function testReplaceWithVariant()
     {
         $store = $this->getAssetStore();
@@ -250,7 +250,7 @@ public function testReplaceWithVariant()
             $store->exists($v1->getFilename(), $v1->getHash(), 'boom'),
             sprintf('A variant of %s has been created', $v1->getFilename())
         );
-        
+
         // Let's replace the content of the main file and publish it
         $download->setFromString($v2Content, $v2->getFilename());
         $object1->write();
diff --git a/tests/php/Dev/Tasks/FileMigrationHelperTest.php b/tests/php/Dev/Tasks/FileMigrationHelperTest.php
index 2ea42fb8..e7f13120 100644
--- a/tests/php/Dev/Tasks/FileMigrationHelperTest.php
+++ b/tests/php/Dev/Tasks/FileMigrationHelperTest.php
@@ -50,7 +50,7 @@ protected function getBasePath()
     }
 
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -164,7 +164,7 @@ function ($args) {
         )->execute();
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         Filesystem::removeFolder($this->getBasePath());
@@ -283,7 +283,7 @@ private function individualImage(Image $file)
         $fullFilename = TestAssetStore::base_path() . '/' . $file->getFilename();
         $dir = dirname($fullFilename);
         $baseFilename = basename($fullFilename);
-        $this->assertFileNotExists($dir . '/_resampled');
+        $this->assertFileDoesNotExist($dir . '/_resampled');
         $this->assertFileExists($dir . '/' . $baseFilename);
 
         // Test that SS3.3 variants have been migrated
diff --git a/tests/php/Dev/Tasks/LegacyThumbnailMigrationHelperTest.php b/tests/php/Dev/Tasks/LegacyThumbnailMigrationHelperTest.php
index b03ed5a7..515e9043 100644
--- a/tests/php/Dev/Tasks/LegacyThumbnailMigrationHelperTest.php
+++ b/tests/php/Dev/Tasks/LegacyThumbnailMigrationHelperTest.php
@@ -41,7 +41,7 @@ protected function getBasePath()
     }
 
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -61,7 +61,7 @@ public function setUp()
         }
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         Filesystem::removeFolder($this->getBasePath());
@@ -90,7 +90,7 @@ public function testMigratesWithExistingThumbnailInNewLocation($coreVersion)
         // Moved contains store relative paths
         $base = TestAssetStore::base_path();
 
-        $this->assertFileNotExists(
+        $this->assertFileDoesNotExist(
             $this->joinPaths($base, $expectedLegacyPath),
             'Legacy file has been removed'
         );
@@ -131,7 +131,7 @@ public function testMigratesMultipleFilesInSameFolder($coreVersion)
         $base = TestAssetStore::base_path();
 
         foreach ($expected as $expectedLegacyPath => $expectedNewPath) {
-            $this->assertFileNotExists(
+            $this->assertFileDoesNotExist(
                 $this->joinPaths($base, $expectedLegacyPath),
                 'Legacy file has been removed'
             );
@@ -176,7 +176,7 @@ public function testMigrate($fixtureId, $formats, $coreVersion)
             $expectedNewPath,
             'New file is mapped as expected'
         );
-        $this->assertFileNotExists(
+        $this->assertFileDoesNotExist(
             $this->joinPaths($base, $expectedLegacyPath),
             'Legacy file has been removed'
         );
diff --git a/tests/php/Dev/Tasks/NormaliseAccessMigrationHelperTest.php b/tests/php/Dev/Tasks/NormaliseAccessMigrationHelperTest.php
index 093e025c..981e4e6b 100644
--- a/tests/php/Dev/Tasks/NormaliseAccessMigrationHelperTest.php
+++ b/tests/php/Dev/Tasks/NormaliseAccessMigrationHelperTest.php
@@ -41,7 +41,7 @@ protected function getBasePath()
     }
 
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -62,7 +62,7 @@ protected function setUpAssetStore()
         TestAssetStore::activate('NormaliseAccessMigrationHelperTest/assets');
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         Filesystem::removeFolder($this->getBasePath());
@@ -112,11 +112,9 @@ private function getHelper()
         return new Helper('/assets/NormaliseAccessMigrationHelperTest/');
     }
 
-    /**
-     * @expectedException InvalidArgumentException
-     */
     public function testNeedToMoveWithFolder()
     {
+        $this->expectException(\InvalidArgumentException::class);
         /** @var File $file */
         $folder = Folder::find('Uploads');
         $helper = $this->getHelper();
@@ -630,11 +628,9 @@ public function testFindBadFilesWithMultiPublishedVersions()
         );
     }
 
-    /**
-     * @expectedException LogicException
-     */
     public function testNeedToMoveNonExistentFile()
     {
+        $this->expectException(\LogicException::class);
         /** @var File $file */
         $file = $this->objFromFixture(File::class, 'file1');
         $file->CanViewType = InheritedPermissions::LOGGED_IN_USERS;
diff --git a/tests/php/Dev/Tasks/SS4FileMigrationHelperTest.php b/tests/php/Dev/Tasks/SS4FileMigrationHelperTest.php
index 544593d8..fc6a800c 100644
--- a/tests/php/Dev/Tasks/SS4FileMigrationHelperTest.php
+++ b/tests/php/Dev/Tasks/SS4FileMigrationHelperTest.php
@@ -45,7 +45,7 @@ class SS4FileMigrationHelperTest extends SapphireTest
         ]
     ];
 
-    public function setUp()
+    protected function setUp(): void
     {
         Config::nest(); // additional nesting here necessary
         Config::modify()->merge(File::class, 'migrate_legacy_file', false);
@@ -181,7 +181,7 @@ protected function defineDestinationStrategy()
         $store->setPublicResolutionStrategy($public);
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
diff --git a/tests/php/Dev/Tasks/SecureAssetsMigrationHelperTest.php b/tests/php/Dev/Tasks/SecureAssetsMigrationHelperTest.php
index cbda97e0..f74c1bf6 100644
--- a/tests/php/Dev/Tasks/SecureAssetsMigrationHelperTest.php
+++ b/tests/php/Dev/Tasks/SecureAssetsMigrationHelperTest.php
@@ -28,7 +28,7 @@ protected function getBasePath()
     }
 
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -52,7 +52,7 @@ public function setUp()
         }
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         Filesystem::removeFolder($this->getBasePath());
diff --git a/tests/php/Dev/Tasks/TagsToShortcodeHelperTest.php b/tests/php/Dev/Tasks/TagsToShortcodeHelperTest.php
index 2831765d..3b370571 100644
--- a/tests/php/Dev/Tasks/TagsToShortcodeHelperTest.php
+++ b/tests/php/Dev/Tasks/TagsToShortcodeHelperTest.php
@@ -44,7 +44,7 @@ protected function getBasePath()
         return ASSETS_PATH . '/TagsToShortcodeHelperTest';
     }
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->setupAssetStore();
@@ -67,7 +67,7 @@ private function setupAssetStore()
         }
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         Filesystem::removeFolder($this->getBasePath());
@@ -84,17 +84,17 @@ public function testRewrite()
         $documentID = $this->idFromFixture(File::class, 'document');
         $imageID = $this->idFromFixture(Image::class, 'image1');
 
-        $this->assertContains(
+        $this->assertStringContainsString(
             sprintf('<p id="filelink">file link <a href="[file_link,id=%d]">link to file</a></p>', $documentID),
             $newPage->Content
         );
 
-        $this->assertContains(
+        $this->assertStringContainsString(
             sprintf('<p id="image">[image src="/assets/33be1b95cb/myimage.jpg" id="%d"]</p>', $imageID),
             $newPage->Content
         );
 
-        $this->assertContains(
+        $this->assertStringContainsString(
             sprintf(
                 '<p id="variant">[image src="/assets/33be1b95cb/myimage.jpg" width="64" height="64" id="%d"]</p>',
                 $imageID
@@ -137,17 +137,17 @@ public function testLivePageRewrite()
         $documentID = $this->idFromFixture(File::class, 'document');
         $imageID = $this->idFromFixture(Image::class, 'image1');
 
-        $this->assertContains(
+        $this->assertStringContainsString(
             sprintf('<p id="filelink">file link <a href="[file_link,id=%d]">link to file</a></p>', $documentID),
             $newPage->Content
         );
 
-        $this->assertContains(
+        $this->assertStringContainsString(
             sprintf('<p id="image">[image src="/assets/33be1b95cb/myimage.jpg" id="%d"]</p>', $imageID),
             $newPage->Content
         );
 
-        $this->assertContains(
+        $this->assertStringContainsString(
             sprintf(
                 '<p id="variant">[image src="/assets/33be1b95cb/myimage.jpg" width="64" height="64" id="%d"]</p>',
                 $imageID
diff --git a/tests/php/FileFinderTest.php b/tests/php/FileFinderTest.php
index 03a6b187..d4e0e017 100644
--- a/tests/php/FileFinderTest.php
+++ b/tests/php/FileFinderTest.php
@@ -35,11 +35,9 @@ public function testBasicOperation()
         );
     }
 
-    /**
-     * @expectedException InvalidArgumentException
-     */
     public function testInvalidOptionThrowsException()
     {
+        $this->expectException(\InvalidArgumentException::class);
         $finder = new FileFinder();
         $finder->setOption('this_doesnt_exist', 'ok');
     }
diff --git a/tests/php/FileNameFilterTest.php b/tests/php/FileNameFilterTest.php
index e8c38b0e..4c8ebad8 100644
--- a/tests/php/FileNameFilterTest.php
+++ b/tests/php/FileNameFilterTest.php
@@ -8,7 +8,7 @@
 
 class FileNameFilterTest extends SapphireTest
 {
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/php/FileTest.php b/tests/php/FileTest.php
index dfc3b6fa..33022b2f 100644
--- a/tests/php/FileTest.php
+++ b/tests/php/FileTest.php
@@ -37,7 +37,7 @@ class FileTest extends SapphireTest
         MyCustomFile::class
     ];
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->logInWithPermission('ADMIN');
@@ -70,7 +70,7 @@ public function setUp()
         }
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
diff --git a/tests/php/FilenameParsing/FileIDHelperResolutionStrategyTest.php b/tests/php/FilenameParsing/FileIDHelperResolutionStrategyTest.php
index 4665954b..07c9fc20 100644
--- a/tests/php/FilenameParsing/FileIDHelperResolutionStrategyTest.php
+++ b/tests/php/FilenameParsing/FileIDHelperResolutionStrategyTest.php
@@ -30,7 +30,7 @@ class FileIDHelperResolutionStrategyTest extends SapphireTest
     /** @var Filesystem */
     private $fs;
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         Sha1FileHashingService::flush();
@@ -49,7 +49,7 @@ public function setUp()
         Injector::inst()->registerService($this->fs, Filesystem::class . '.public');
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
 
diff --git a/tests/php/FilenameParsing/HashFileIDHelperTest.php b/tests/php/FilenameParsing/HashFileIDHelperTest.php
index f13194b5..616e890f 100644
--- a/tests/php/FilenameParsing/HashFileIDHelperTest.php
+++ b/tests/php/FilenameParsing/HashFileIDHelperTest.php
@@ -168,11 +168,9 @@ public function variantIn()
         ];
     }
 
-    /**
-     * @expectedException InvalidArgumentException
-     */
     public function testHashlessBuildFileID()
     {
+        $this->expectException(\InvalidArgumentException::class);
         $this->getHelper()->buildFileID('Filename.txt', '');
     }
 }
diff --git a/tests/php/FilesystemTest.php b/tests/php/FilesystemTest.php
index 62fc2c79..5c436cb0 100644
--- a/tests/php/FilesystemTest.php
+++ b/tests/php/FilesystemTest.php
@@ -24,7 +24,7 @@ class FilesystemTest extends SapphireTest
      */
     protected $root;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->root = vfsStream::setup(
@@ -74,7 +74,7 @@ public function testRemoveFolderWithFiles()
 
         Filesystem::removeFolder($folderPath);
         $this->assertDirectoryNotExists($folderPath);
-        $this->assertFileNotExists($filePath);
+        $this->assertFileDoesNotExist($filePath);
     }
 
     public function testRemoveFolderWithSubFolder()
@@ -90,7 +90,7 @@ public function testRemoveFolderWithSubFolder()
         Filesystem::removeFolder($folderPath);
         $this->assertDirectoryNotExists($folderPath);
         $this->assertDirectoryNotExists($emptySubfolder);
-        $this->assertFileNotExists($filePath);
+        $this->assertFileDoesNotExist($filePath);
     }
 
     public function testRemoveFolderWithFalsyFile()
@@ -102,7 +102,7 @@ public function testRemoveFolderWithFalsyFile()
 
         Filesystem::removeFolder($folderPath);
         $this->assertDirectoryNotExists($folderPath);
-        $this->assertFileNotExists($filePath);
+        $this->assertFileDoesNotExist($filePath);
     }
 
     public function testRemovedFolderContentsOnly()
@@ -121,6 +121,6 @@ public function testRemovedFolderContentsOnly()
         $this->assertDirectoryExists($folderPath);
         $this->assertDirectoryNotExists($emptySubfolder);
         $this->assertDirectoryNotExists($notEmptySubfolder);
-        $this->assertFileNotExists($filePath);
+        $this->assertFileDoesNotExist($filePath);
     }
 }
diff --git a/tests/php/Flysystem/AssetAdapterTest.php b/tests/php/Flysystem/AssetAdapterTest.php
index 59afc730..117888e5 100644
--- a/tests/php/Flysystem/AssetAdapterTest.php
+++ b/tests/php/Flysystem/AssetAdapterTest.php
@@ -17,7 +17,7 @@ class AssetAdapterTest extends SapphireTest
 
     protected $originalServer = null;
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -38,7 +38,7 @@ public function setUp()
         $this->originalServer = $_SERVER;
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         if ($this->rootDir) {
             Filesystem::removeFolder($this->rootDir);
@@ -56,19 +56,19 @@ public function testPublicAdapter()
         $_SERVER['SERVER_SOFTWARE'] = 'Apache/2.2.22 (Win64) PHP/5.3.13';
         $adapter = new PublicAssetAdapter($this->rootDir);
         $this->assertFileExists($this->rootDir . '/.htaccess');
-        $this->assertFileNotExists($this->rootDir . '/web.config');
+        $this->assertFileDoesNotExist($this->rootDir . '/web.config');
 
         $htaccess = $adapter->read('.htaccess');
         $content = $htaccess['contents'];
         // Allowed extensions set
-        $this->assertContains('RewriteCond %{REQUEST_URI} !^[^.]*[^\/]*\.(?i:', $content);
+        $this->assertStringContainsString('RewriteCond %{REQUEST_URI} !^[^.]*[^\/]*\.(?i:', $content);
         foreach (File::getAllowedExtensions() as $extension) {
-            $this->assertRegExp('/\b'.preg_quote($extension).'\b/', $content);
+            $this->assertMatchesRegularExpression('/\b'.preg_quote($extension).'\b/', $content);
         }
 
         // Rewrite rules
-        $this->assertContains('RewriteRule .* ../index.php [QSA]', $content);
-        $this->assertContains('RewriteRule error[^\\\\/]*\\.html$ - [L]', $content);
+        $this->assertStringContainsString('RewriteRule .* ../index.php [QSA]', $content);
+        $this->assertStringContainsString('RewriteRule error[^\\\\/]*\\.html$ - [L]', $content);
 
         // Test flush restores invalid content
         file_put_contents($this->rootDir . '/.htaccess', '# broken content');
@@ -85,7 +85,7 @@ public function testProtectedAdapter()
         $_SERVER['SERVER_SOFTWARE'] = 'Apache/2.2.22 (Win64) PHP/5.3.13';
         $adapter = new ProtectedAssetAdapter($this->rootDir . '/.protected');
         $this->assertFileExists($this->rootDir . '/.protected/.htaccess');
-        $this->assertFileNotExists($this->rootDir . '/.protected/web.config');
+        $this->assertFileDoesNotExist($this->rootDir . '/.protected/web.config');
 
         // Test url
         $this->assertEquals('/assets/file.jpg', $adapter->getProtectedUrl('file.jpg'));
diff --git a/tests/php/Flysystem/FlysystemAssetStoreTest.php b/tests/php/Flysystem/FlysystemAssetStoreTest.php
index 1410a45a..a2f1dc6e 100644
--- a/tests/php/Flysystem/FlysystemAssetStoreTest.php
+++ b/tests/php/Flysystem/FlysystemAssetStoreTest.php
@@ -41,7 +41,7 @@ class FlysystemAssetStoreTest extends SapphireTest
     /** @var FileResolutionStrategy */
     protected $protectedStrategy;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -136,11 +136,9 @@ public function testPublicFilesystem()
         $this->assertEquals($this->publicFilesystem, $assetStore->getPublicFilesystem());
     }
 
-    /**
-     * @expectedException InvalidArgumentException
-     */
     public function testBadPublicFilesystem()
     {
+        $this->expectException(\InvalidArgumentException::class);
         $assetStore = new FlysystemAssetStore();
         $assetStore->setPublicFilesystem($this->protectedFilesystem);
     }
@@ -152,11 +150,9 @@ public function testProtectedFilesystem()
         $this->assertEquals($this->protectedFilesystem, $assetStore->getProtectedFilesystem());
     }
 
-    /**
-     * @expectedException InvalidArgumentException
-     */
     public function testBadProtectedFilesystem()
     {
+        $this->expectException(\InvalidArgumentException::class);
         $assetStore = new FlysystemAssetStore();
         $assetStore->setProtectedFilesystem($this->publicFilesystem);
     }
diff --git a/tests/php/Flysystem/FlysystemAssetStoreUpdateResponseTest.php b/tests/php/Flysystem/FlysystemAssetStoreUpdateResponseTest.php
index 379a79cf..2827ff95 100644
--- a/tests/php/Flysystem/FlysystemAssetStoreUpdateResponseTest.php
+++ b/tests/php/Flysystem/FlysystemAssetStoreUpdateResponseTest.php
@@ -26,7 +26,7 @@ class FlysystemAssetStoreUpdateResponseTest extends SapphireTest
     /**
      * @skipUpgrade
      */
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -59,7 +59,7 @@ public function setUp()
         $this->hash = substr(sha1('hello'), 0, 10);
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
diff --git a/tests/php/FolderNameFilterTest.php b/tests/php/FolderNameFilterTest.php
index 4951d211..66609209 100644
--- a/tests/php/FolderNameFilterTest.php
+++ b/tests/php/FolderNameFilterTest.php
@@ -8,7 +8,7 @@
 
 class FolderNameFilterTest extends SapphireTest
 {
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/php/FolderTest.php b/tests/php/FolderTest.php
index f3ba7b89..eeb78ace 100644
--- a/tests/php/FolderTest.php
+++ b/tests/php/FolderTest.php
@@ -24,7 +24,7 @@ class FolderTest extends SapphireTest
 
     protected static $fixture_file = 'FileTest.yml';
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -66,7 +66,7 @@ public function setUp()
         }
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
@@ -131,7 +131,7 @@ public function testFindOrMake()
         );
 
         // Folder does not exist until it contains files
-        $this->assertFileNotExists(
+        $this->assertFileDoesNotExist(
             TestAssetStore::getLocalPath($folder),
             'Empty folder does not have a filesystem record automatically'
         );
diff --git a/tests/php/GDImageTest.php b/tests/php/GDImageTest.php
index 024921a6..4e57f66c 100644
--- a/tests/php/GDImageTest.php
+++ b/tests/php/GDImageTest.php
@@ -11,7 +11,7 @@
 
 class GDImageTest extends ImageTest
 {
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/php/ImageManipulationTest.php b/tests/php/ImageManipulationTest.php
index 2726388f..5c7bf078 100644
--- a/tests/php/ImageManipulationTest.php
+++ b/tests/php/ImageManipulationTest.php
@@ -29,7 +29,7 @@ class ImageManipulationTest extends SapphireTest
 {
     protected static $fixture_file = 'ImageTest.yml';
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -53,7 +53,7 @@ public function setUp()
         ]);
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
diff --git a/tests/php/ImageTest.php b/tests/php/ImageTest.php
index 21485e11..68a744b3 100644
--- a/tests/php/ImageTest.php
+++ b/tests/php/ImageTest.php
@@ -28,7 +28,7 @@ abstract class ImageTest extends SapphireTest
 {
     protected static $fixture_file = 'ImageTest.yml';
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -52,7 +52,7 @@ public function setUp()
         ]);
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
@@ -315,7 +315,7 @@ public function testImageResizeValidate()
      */
     public function testImageResizeInvalid($width, $height, $error)
     {
-        $this->expectException(InvalidArgumentException::class);
+        $this->expectException(\InvalidArgumentException::class);
         $this->expectExceptionMessage($error);
         /** @var Image $image */
         $image = $this->objFromFixture(Image::class, 'imageWithoutTitle');
@@ -331,11 +331,9 @@ public function providerTestImageResizeInvalid()
         ];
     }
 
-    /**
-     * @expectedException InvalidArgumentException
-     */
     public function testGenerateImageWithInvalidParameters()
     {
+        $this->expectException(\InvalidArgumentException::class);
         $image = $this->objFromFixture(Image::class, 'imageWithoutTitle');
         $image->ScaleHeight('String');
         $image->Pad(600, 600, 'XXXXXX');
@@ -348,7 +346,7 @@ public function testCacheFilename()
         $imageFilename = $imageFirst->getURL();
             // Encoding of the arguments is duplicated from cacheFilename
         $neededPart = 'Pad' . Convert::base64url_encode([200,200,'CCCCCC', 0]);
-        $this->assertContains($neededPart, $imageFilename, 'Filename for cached image is correctly generated');
+        $this->assertStringContainsString($neededPart, $imageFilename, 'Filename for cached image is correctly generated');
     }
 
     public function testGenerateImageInSameFolderAsOriginal()
@@ -404,11 +402,9 @@ public function testVariantParts()
         );
     }
 
-    /**
-     * @expectedException \InvalidArgumentException
-     */
     public function testVariantPartsThrowsOnInvalidName()
     {
+        $this->expectException(\InvalidArgumentException::class);
         /** @var Image $image */
         $image = singleton(Image::class);
         $args = ['foo'];
diff --git a/tests/php/ImagickImageTest.php b/tests/php/ImagickImageTest.php
index d1194cd5..d9ca5ba3 100644
--- a/tests/php/ImagickImageTest.php
+++ b/tests/php/ImagickImageTest.php
@@ -11,7 +11,7 @@
 
 class ImagickImageTest extends ImageTest
 {
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/php/ProtectedFileControllerTest.php b/tests/php/ProtectedFileControllerTest.php
index 7047e31c..6ec9903d 100644
--- a/tests/php/ProtectedFileControllerTest.php
+++ b/tests/php/ProtectedFileControllerTest.php
@@ -20,7 +20,7 @@ class ProtectedFileControllerTest extends FunctionalTest
 {
     protected static $fixture_file = 'FileTest.yml';
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -47,7 +47,7 @@ public function setUp()
         $protectedFile->protectFile();
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
diff --git a/tests/php/PublicAssetAdapterTest.php b/tests/php/PublicAssetAdapterTest.php
index 257c340d..e726b092 100644
--- a/tests/php/PublicAssetAdapterTest.php
+++ b/tests/php/PublicAssetAdapterTest.php
@@ -8,7 +8,7 @@
 
 class PublicAssetAdapterTest extends SapphireTest
 {
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         Director::config()->set(
diff --git a/tests/php/RedirectFileControllerTest.php b/tests/php/RedirectFileControllerTest.php
index fcbf7da3..14ec74e3 100644
--- a/tests/php/RedirectFileControllerTest.php
+++ b/tests/php/RedirectFileControllerTest.php
@@ -25,7 +25,7 @@ class RedirectFileControllerTest extends FunctionalTest
 
     protected $autoFollowRedirection = false;
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -57,7 +57,7 @@ public function setUp()
         }
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
@@ -216,7 +216,7 @@ public function testRedirectWithDraftFile($fixtureID)
     public function testRedirectAfterPublishSecondVersion($fixtureID)
     {
         $hashHelper = new HashFileIDHelper();
-        
+
         /** @var File $file */
         $file = $this->objFromFixture(File::class, $fixtureID);
         $file->publishSingle();
@@ -384,7 +384,7 @@ public function testVariantRedirect($folderFixture, $filename, $ext)
         $hash = substr($file->getHash(), 0, 10);
         $ico = $file->ScaleWidth(32);
         $icoUrl = $ico->getURL(false);
-        
+
         $suffix = $ico->getVariant();
 
         $response = $this->get($icoUrl);
diff --git a/tests/php/RedirectKeepArchiveFileControllerTest.php b/tests/php/RedirectKeepArchiveFileControllerTest.php
index 8fb63943..9562e4eb 100644
--- a/tests/php/RedirectKeepArchiveFileControllerTest.php
+++ b/tests/php/RedirectKeepArchiveFileControllerTest.php
@@ -20,7 +20,7 @@
 class RedirectKeepArchiveFileControllerTest extends RedirectFileControllerTest
 {
 
-    public function setUp()
+    protected function setUp(): void
     {
         File::config()->set('keep_archived_assets', true);
         parent::setUp();
@@ -43,7 +43,7 @@ public function testRedirectAfterUnpublish($fixtureID)
         );
         $file->write();
         $v2HashUrl = $file->getURL(false);
-        
+
         $file->publishSingle();
         $v2Url = $file->getURL(false);
 
diff --git a/tests/php/Shortcodes/FileBrokenLinksTest.php b/tests/php/Shortcodes/FileBrokenLinksTest.php
index 620664c0..5fefe562 100644
--- a/tests/php/Shortcodes/FileBrokenLinksTest.php
+++ b/tests/php/Shortcodes/FileBrokenLinksTest.php
@@ -17,7 +17,7 @@ class FileBrokenLinksTest extends SapphireTest
         EditableObject::class,
     ];
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -25,7 +25,7 @@ public function setUp()
         TestAssetStore::activate('FileBrokenLinksTest');
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
diff --git a/tests/php/Shortcodes/FileLinkTrackingTest.php b/tests/php/Shortcodes/FileLinkTrackingTest.php
index f42950f2..1e8dfaaf 100644
--- a/tests/php/Shortcodes/FileLinkTrackingTest.php
+++ b/tests/php/Shortcodes/FileLinkTrackingTest.php
@@ -19,7 +19,7 @@ class FileLinkTrackingTest extends SapphireTest
 
     protected static $fixture_file = "FileLinkTrackingTest.yml";
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -59,7 +59,7 @@ public function setUp()
         $page->write();
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
@@ -77,11 +77,11 @@ public function testFileRenameUpdatesDraftAndPublishedPages()
         $page->publishRecursive();
 
         // Live and stage pages both have link to public file
-        $this->assertContains(
+        $this->assertStringContainsString(
             '<img src="/assets/FileLinkTrackingTest/testscript-test-file.jpg"',
             $page->dbObject('Content')->forTemplate()
         );
-        $this->assertContains(
+        $this->assertStringContainsString(
             '<p><a href="/assets/FileLinkTrackingTest/testscript-test-file.txt">Working Link</a></p>',
             $page->dbObject('Another')->forTemplate()
         );
@@ -90,11 +90,11 @@ public function testFileRenameUpdatesDraftAndPublishedPages()
             Versioned::set_stage(Versioned::LIVE);
             /** @var EditableObject $pageLive */
             $pageLive = EditableObject::get()->byID($page->ID);
-            $this->assertContains(
+            $this->assertStringContainsString(
                 '<img src="/assets/FileLinkTrackingTest/testscript-test-file.jpg"',
                 $pageLive->dbObject('Content')->forTemplate()
             );
-            $this->assertContains(
+            $this->assertStringContainsString(
                 '<p><a href="/assets/FileLinkTrackingTest/testscript-test-file.txt">Working Link</a></p>',
                 $pageLive->dbObject('Another')->forTemplate()
             );
@@ -119,14 +119,14 @@ public function testFileRenameUpdatesDraftAndPublishedPages()
         // Note that the "secure" url doesn't have the "FileLinkTrackingTest" component because
         // the mocked test location disappears for secure files.
         $page = EditableObject::get()->byID($page->ID);
-        $this->assertContains(
+        $this->assertStringContainsString(
             '<img src="/assets/5a5ee24e44/renamed-test-file.jpg"',
             $page->dbObject('Content')->forTemplate()
         );
         Versioned::withVersionedMode(function () use ($page) {
             Versioned::set_stage(Versioned::LIVE);
             $pageLive = EditableObject::get()->byID($page->ID);
-            $this->assertContains(
+            $this->assertStringContainsString(
                 '<img src="/assets/FileLinkTrackingTest/testscript-test-file.jpg"',
                 $pageLive->dbObject('Content')->forTemplate()
             );
@@ -136,14 +136,14 @@ public function testFileRenameUpdatesDraftAndPublishedPages()
         // Although the old live page will still point to the old record.
         $image1->publishRecursive();
         $page = EditableObject::get()->byID($page->ID);
-        $this->assertContains(
+        $this->assertStringContainsString(
             '<img src="/assets/FileLinkTrackingTest/renamed-test-file.jpg"',
             $page->dbObject('Content')->forTemplate()
         );
         Versioned::withVersionedMode(function () use ($page) {
             Versioned::set_stage(Versioned::LIVE);
             $pageLive = EditableObject::get()->byID($page->ID);
-            $this->assertContains(
+            $this->assertStringContainsString(
                 '<img src="/assets/FileLinkTrackingTest/renamed-test-file.jpg"',
                 $pageLive->dbObject('Content')->forTemplate()
             );
@@ -152,14 +152,14 @@ public function testFileRenameUpdatesDraftAndPublishedPages()
         // Publishing the page after publishing the asset should retain linking
         $page->publishRecursive();
         $page = EditableObject::get()->byID($page->ID);
-        $this->assertContains(
+        $this->assertStringContainsString(
             '<img src="/assets/FileLinkTrackingTest/renamed-test-file.jpg"',
             $page->dbObject('Content')->forTemplate()
         );
         Versioned::withVersionedMode(function () use ($page) {
             Versioned::set_stage(Versioned::LIVE);
             $pageLive = EditableObject::get()->byID($page->ID);
-            $this->assertContains(
+            $this->assertStringContainsString(
                 '<img src="/assets/FileLinkTrackingTest/renamed-test-file.jpg"',
                 $pageLive->dbObject('Content')->forTemplate()
             );
@@ -193,7 +193,7 @@ public function testTwoFileRenamesInARowWork()
         Versioned::withVersionedMode(function () use ($page) {
             Versioned::set_stage(Versioned::LIVE);
             $livePage = EditableObject::get()->byID($page->ID);
-            $this->assertContains(
+            $this->assertStringContainsString(
                 '<img src="/assets/FileLinkTrackingTest/testscript-test-file.jpg"',
                 $livePage->dbObject('Content')->forTemplate()
             );
@@ -214,7 +214,7 @@ public function testTwoFileRenamesInARowWork()
 
         // Confirm that the correct image is shown in both the draft and live site
         $page = EditableObject::get()->byID($page->ID);
-        $this->assertContains(
+        $this->assertStringContainsString(
             '<img src="/assets/FileLinkTrackingTest/renamed-test-file-second-time.jpg"',
             $page->dbObject('Content')->forTemplate()
         );
@@ -224,7 +224,7 @@ public function testTwoFileRenamesInARowWork()
         Versioned::withVersionedMode(function () use ($page) {
             Versioned::set_stage(Versioned::LIVE);
             $pageLive = EditableObject::get()->byID($page->ID);
-            $this->assertContains(
+            $this->assertStringContainsString(
                 '<img src="/assets/FileLinkTrackingTest/renamed-test-file-second-time.jpg"',
                 $pageLive->dbObject('Content')->forTemplate()
             );
@@ -243,11 +243,11 @@ public function testBrokenCSSClasses()
         $file = $this->objFromFixture(File::class, 'file1');
         $fileID = $file->ID;
 
-        $this->assertContains(
+        $this->assertStringContainsString(
             '<p><a href="/assets/FileLinkTrackingTest/testscript-test-file.txt">Working Link</a></p>',
             $page->dbObject('Another')->forTemplate()
         );
-        $this->assertContains(
+        $this->assertStringContainsString(
             sprintf('<p><a href="[file_link,id=%d]">Working Link</a></p>', $fileID),
             $page->Another
         );
@@ -255,11 +255,11 @@ public function testBrokenCSSClasses()
         // Deleting file should trigger css class
         $file->delete();
         $page = EditableObject::get()->byID($page->ID);
-        $this->assertContains(
+        $this->assertStringContainsString(
             '<p><a href="" class="ss-broken">Working Link</a></p>',
             $page->dbObject('Another')->forTemplate()
         );
-        $this->assertContains(
+        $this->assertStringContainsString(
             sprintf('<p><a href="[file_link,id=%d]" class="ss-broken">Working Link</a></p>', $fileID),
             $page->Another
         );
@@ -269,11 +269,11 @@ public function testBrokenCSSClasses()
         $fileLive = Versioned::get_by_stage(File::class, Versioned::LIVE)->byID($fileID);
         $fileLive->doRevertToLive();
         $page = EditableObject::get()->byID($page->ID);
-        $this->assertContains(
+        $this->assertStringContainsString(
             sprintf('<p><a href="[file_link,id=%d]">Working Link</a></p>', $fileID),
             $page->Another
         );
-        $this->assertContains(
+        $this->assertStringContainsString(
             '<p><a href="/assets/FileLinkTrackingTest/testscript-test-file.txt">Working Link</a></p>',
             $page->dbObject('Another')->forTemplate()
         );
diff --git a/tests/php/Shortcodes/FileShortcodeProviderTest.php b/tests/php/Shortcodes/FileShortcodeProviderTest.php
index 512748f0..05b0ff9e 100644
--- a/tests/php/Shortcodes/FileShortcodeProviderTest.php
+++ b/tests/php/Shortcodes/FileShortcodeProviderTest.php
@@ -23,7 +23,7 @@ class FileShortcodeProviderTest extends SapphireTest
 {
     protected static $fixture_file = '../FileTest.yml';
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->logInWithPermission('ADMIN');
@@ -49,7 +49,7 @@ public function setUp()
         }
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
diff --git a/tests/php/Shortcodes/ImageShortcodeProviderTest.php b/tests/php/Shortcodes/ImageShortcodeProviderTest.php
index 4c16f375..be43739f 100644
--- a/tests/php/Shortcodes/ImageShortcodeProviderTest.php
+++ b/tests/php/Shortcodes/ImageShortcodeProviderTest.php
@@ -18,7 +18,7 @@ class ImageShortcodeProviderTest extends SapphireTest
 
     protected static $fixture_file = '../ImageTest.yml';
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -34,7 +34,7 @@ public function setUp()
         }
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
@@ -160,23 +160,23 @@ public function testLazyLoading()
 
         // regular shortcode
         $shortcode = '[image id="' . $id . '" width="300" height="200"]';
-        $this->assertContains('loading="lazy"', $parser->parse($shortcode));
+        $this->assertStringContainsString('loading="lazy"', $parser->parse($shortcode));
 
         // missing width
         $shortcode = '[image id="' . $id . '" height="200"]';
-        $this->assertNotContains('loading="lazy"', $parser->parse($shortcode));
+        $this->assertStringNotContainsString('loading="lazy"', $parser->parse($shortcode));
 
         // missing height
         $shortcode = '[image id="' . $id . '" width="300"]';
-        $this->assertNotContains('loading="lazy"', $parser->parse($shortcode));
+        $this->assertStringNotContainsString('loading="lazy"', $parser->parse($shortcode));
 
         // loading="eager"
         $shortcode = '[image id="' . $id . '" width="300" height="200" loading="eager"]';
-        $this->assertNotContains('loading="lazy"', $parser->parse($shortcode));
+        $this->assertStringNotContainsString('loading="lazy"', $parser->parse($shortcode));
 
         // loading="nonsense"
         $shortcode = '[image id="' . $id . '" width="300" height="200" loading="nonsense"]';
-        $this->assertContains('loading="lazy"', $parser->parse($shortcode));
+        $this->assertStringContainsString('loading="lazy"', $parser->parse($shortcode));
 
         // globally disabled
         Config::withConfig(function () use ($id, $parser) {
@@ -184,7 +184,7 @@ public function testLazyLoading()
             // clear-provider-cache is so that we don't get a cached result from the 'regular shortcode'
             // assertion earlier in this function from ImageShortCodeProvider::handle_shortcode()
             $shortcode = '[image id="' . $id . '" width="300" height="200" clear-provider-cache="1"]';
-            $this->assertNotContains('loading="lazy"', $parser->parse($shortcode));
+            $this->assertStringNotContainsString('loading="lazy"', $parser->parse($shortcode));
         });
     }
 }
diff --git a/tests/php/Storage/AssetStoreTest.php b/tests/php/Storage/AssetStoreTest.php
index e05cddd5..fac99de2 100644
--- a/tests/php/Storage/AssetStoreTest.php
+++ b/tests/php/Storage/AssetStoreTest.php
@@ -24,7 +24,7 @@ class AssetStoreTest extends SapphireTest
     /**
      * @skipUpgrade
      */
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -32,7 +32,7 @@ public function setUp()
         TestAssetStore::activate('AssetStoreTest');
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
@@ -604,8 +604,8 @@ public function testProtect()
 
         // Test protected file storage
         $backend->protect($fishTuple['Filename'], $fishTuple['Hash']);
-        $this->assertFileNotExists(ASSETS_PATH . '/AssetStoreTest/parent/lovely-fish.jpg');
-        $this->assertFileNotExists(ASSETS_PATH . '/AssetStoreTest/parent/lovely-fish__copy.jpg');
+        $this->assertFileDoesNotExist(ASSETS_PATH . '/AssetStoreTest/parent/lovely-fish.jpg');
+        $this->assertFileDoesNotExist(ASSETS_PATH . '/AssetStoreTest/parent/lovely-fish__copy.jpg');
         $this->assertFileExists(ASSETS_PATH . '/AssetStoreTest/.protected/parent/a870de278b/lovely-fish.jpg');
         $this->assertFileExists(ASSETS_PATH . '/AssetStoreTest/.protected/parent/a870de278b/lovely-fish__copy.jpg');
         $this->assertEquals(
@@ -633,8 +633,8 @@ public function testProtect()
         $backend->publish($fishTuple['Filename'], $fishTuple['Hash']);
         $this->assertFileExists(ASSETS_PATH . '/AssetStoreTest/parent/lovely-fish.jpg');
         $this->assertFileExists(ASSETS_PATH . '/AssetStoreTest/parent/lovely-fish__copy.jpg');
-        $this->assertFileNotExists(ASSETS_PATH . '/AssetStoreTest/.protected/parent/a870de278b/lovely-fish.jpg');
-        $this->assertFileNotExists(ASSETS_PATH . '/AssetStoreTest/.protected/parent/a870de278b/lovely-fish__copy.jpg');
+        $this->assertFileDoesNotExist(ASSETS_PATH . '/AssetStoreTest/.protected/parent/a870de278b/lovely-fish.jpg');
+        $this->assertFileDoesNotExist(ASSETS_PATH . '/AssetStoreTest/.protected/parent/a870de278b/lovely-fish__copy.jpg');
         $this->assertEquals(
             AssetStore::VISIBILITY_PUBLIC,
             $backend->getVisibility($fishTuple['Filename'], $fishTuple['Hash'])
diff --git a/tests/php/Storage/DBFileTest.php b/tests/php/Storage/DBFileTest.php
index 21c3fee9..9108a0c2 100644
--- a/tests/php/Storage/DBFileTest.php
+++ b/tests/php/Storage/DBFileTest.php
@@ -21,7 +21,7 @@ class DBFileTest extends SapphireTest
 
     protected $usesDatabase = true;
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -30,7 +30,7 @@ public function setUp()
         Director::config()->update('alternate_base_url', '/mysite/');
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
@@ -54,7 +54,7 @@ public function testRender()
 
         // Test download tag
         $obj->MyFile->setFromString('puppies', 'subdir/puppy-document.txt');
-        $this->assertContains(
+        $this->assertStringContainsString(
             '<a href="/mysite/assets/subdir/2a17a9cb4b/puppy-document.txt" title="puppy-document.txt" download="puppy-document.txt">',
             trim($obj->MyFile->forTemplate())
         );
diff --git a/tests/php/Storage/Sha1FileHashingServiceTest.php b/tests/php/Storage/Sha1FileHashingServiceTest.php
index bda3f3e7..8a4f2871 100644
--- a/tests/php/Storage/Sha1FileHashingServiceTest.php
+++ b/tests/php/Storage/Sha1FileHashingServiceTest.php
@@ -40,7 +40,7 @@ class Sha1FileHashingServiceTest extends SapphireTest
 
     private $fileID = 'Sha1FileHashingServiceTest/Pangram.txt';
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -59,7 +59,7 @@ public function setUp()
         Sha1FileHashingService::flush();
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         parent::tearDown();
         $this->publicFs->deleteDir('Sha1FileHashingServiceTest');
@@ -110,7 +110,7 @@ public function testComputeMissingFile()
 
     public function testComputeBadFilesystem()
     {
-        $this->expectException(InvalidArgumentException::class);
+        $this->expectException(\InvalidArgumentException::class);
         $service = new Sha1FileHashingService();
         $service->computeFromFile($this->fileID, AssetStore::CONFLICT_OVERWRITE);
     }
@@ -174,7 +174,7 @@ public function testCompare()
 
     public function testCompareWithEmptyFirstHash()
     {
-        $this->expectException(InvalidArgumentException::class);
+        $this->expectException(\InvalidArgumentException::class);
 
         $service = new Sha1FileHashingService();
         $this->assertTrue($service->compare('', $this->protectedHash));
@@ -182,7 +182,7 @@ public function testCompareWithEmptyFirstHash()
 
     public function testCompareWithEmptySecondHash()
     {
-        $this->expectException(InvalidArgumentException::class);
+        $this->expectException(\InvalidArgumentException::class);
 
         $service = new Sha1FileHashingService();
         $this->assertTrue($service->compare($this->protectedHash, ''));
@@ -266,8 +266,8 @@ public function testInvalidCharacterCacheKey()
             ['Mit_Teamgeist_zum_großen_Paddelerlebnis.pdf', 'file-system']
         );
 
-        $this->assertNotContains('/', $cacheKey);
+        $this->assertStringNotContainsString('/', $cacheKey);
         // Ensure we get a string back after validating the key and it is therefore valid
-        $this->assertInternalType('string', CacheItem::validateKey($cacheKey));
+        $this->assertIsString(CacheItem::validateKey($cacheKey));
     }
 }
diff --git a/tests/php/UploadTest.php b/tests/php/UploadTest.php
index 2925b728..9891eae7 100644
--- a/tests/php/UploadTest.php
+++ b/tests/php/UploadTest.php
@@ -35,7 +35,7 @@ class UploadTest extends SapphireTest
     /**
      * {@inheritDoc}
      */
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         Versioned::set_stage(Versioned::DRAFT);
@@ -48,7 +48,7 @@ public function setUp()
     /**
      * {@inheritDoc}
      */
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         parent::tearDown();
@@ -482,8 +482,8 @@ public function testUploadIntoFileStoresProtectedFilesInsideProtectedFolderWhenC
         // Ensure that the file has been written to a protected folder
         $filePath = TestAssetStore::getLocalPath($file);
         $this->assertFileExists($filePath, 'Test file should be uploaded');
-        $this->assertContains('.protected', $filePath, 'Test file path should be protected');
-        $this->assertContains('my-secret-folder', $filePath, 'Test file should be stored under secret folder');
+        $this->assertStringContainsString('.protected', $filePath, 'Test file path should be protected');
+        $this->assertStringContainsString('my-secret-folder', $filePath, 'Test file should be stored under secret folder');
         $this->assertSame(
             AssetStore::VISIBILITY_PROTECTED,
             $file->getVisibility(),
@@ -519,8 +519,8 @@ public function testUploadIntoFileStoresPublicFilesInsidePublicFolderWhenCanView
         // Ensure that the file has been written to a protected folder
         $filePath = TestAssetStore::getLocalPath($file);
         $this->assertFileExists($filePath, 'Test file should be uploaded');
-        $this->assertNotContains('.protected', $filePath, 'Test file path should be public');
-        $this->assertContains('my-public-folder', $filePath, 'Test file should be stored under public folder');
+        $this->assertStringNotContainsString('.protected', $filePath, 'Test file path should be public');
+        $this->assertStringContainsString('my-public-folder', $filePath, 'Test file should be stored under public folder');
         $this->assertSame(
             AssetStore::VISIBILITY_PUBLIC,
             $file->getVisibility(),
@@ -556,8 +556,8 @@ public function testUploadIntoFileStoresProtectedFilesInsidePublicFolderWhenCanV
         // Ensure that the file has been written to a protected folder
         $filePath = TestAssetStore::getLocalPath($file);
         $this->assertFileExists($filePath, 'Test file should be uploaded');
-        $this->assertContains('.protected', $filePath, 'Test file path should be protected');
-        $this->assertContains('my-public-folder', $filePath, 'Test file should be stored under public folder');
+        $this->assertStringContainsString('.protected', $filePath, 'Test file path should be protected');
+        $this->assertStringContainsString('my-public-folder', $filePath, 'Test file should be stored under public folder');
         $this->assertSame(
             AssetStore::VISIBILITY_PROTECTED,
             $file->getVisibility(),
@@ -593,8 +593,8 @@ public function testUploadIntoFileStoresPublicFilesInsideProtectedFolderWhenCanV
         // Ensure that the file has been written to a protected folder
         $filePath = TestAssetStore::getLocalPath($file);
         $this->assertFileExists($filePath, 'Test file should be uploaded');
-        $this->assertNotContains('.protected', $filePath, 'Test file path should be public');
-        $this->assertContains('my-protected-folder', $filePath, 'Test file should be stored under protected folder');
+        $this->assertStringNotContainsString('.protected', $filePath, 'Test file path should be public');
+        $this->assertStringContainsString('my-protected-folder', $filePath, 'Test file should be stored under protected folder');
         $this->assertSame(
             AssetStore::VISIBILITY_PUBLIC,
             $file->getVisibility(),
diff --git a/tests/php/VersionedFilesMigratorTest.php b/tests/php/VersionedFilesMigratorTest.php
index a2b00788..64e3411d 100644
--- a/tests/php/VersionedFilesMigratorTest.php
+++ b/tests/php/VersionedFilesMigratorTest.php
@@ -31,7 +31,7 @@ protected function getBasePath()
     }
 
 
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -45,7 +45,7 @@ public function setUp()
         }
     }
 
-    public function tearDown()
+    protected function tearDown(): void
     {
         TestAssetStore::reset();
         Filesystem::removeFolder($this->getBasePath());