diff --git a/src/composer.json b/src/composer.json
--- a/src/composer.json
+++ b/src/composer.json
@@ -34,17 +34,13 @@
         "tymon/jwt-auth": "^1.0"
     },
     "require-dev": {
-        "beyondcode/laravel-dump-server": "^1.0",
         "beyondcode/laravel-er-diagram-generator": "^1.3",
         "code-lts/doctum": "^5.1",
-        "filp/whoops": "^2.0",
-        "fzaninotto/faker": "^1.4",
         "kirschbaum-development/mail-intercept": "^0.2.4",
         "laravel/dusk": "~6.15.0",
-        "mockery/mockery": "^1.0",
         "nunomaduro/larastan": "^0.7",
         "phpstan/phpstan": "^0.12",
-        "phpunit/phpunit": "^8"
+        "phpunit/phpunit": "^9"
     },
     "config": {
         "optimize-autoloader": true,
diff --git a/src/database/factories/UserFactory.php b/src/database/factories/UserFactory.php
deleted file mode 100644
--- a/src/database/factories/UserFactory.php
+++ /dev/null
@@ -1,27 +0,0 @@
-<?php
-
-/** @var \Illuminate\Database\Eloquent\Factory $factory */
-use App\User;
-use Illuminate\Support\Str;
-use Faker\Generator as Faker;
-
-/*
-|--------------------------------------------------------------------------
-| Model Factories
-|--------------------------------------------------------------------------
-|
-| This directory should contain each of the model factory definitions for
-| your application. Factories provide a convenient way to generate new
-| model instances for testing / seeding your application's database.
-|
-*/
-
-$factory->define(
-    User::class,
-    function (Faker $faker) {
-        return [
-            'email' => $faker->unique()->safeEmail,
-            'password' => Str::random(64)
-        ];
-    }
-);
diff --git a/src/database/seeds/local/UserSeeder.php b/src/database/seeds/local/UserSeeder.php
--- a/src/database/seeds/local/UserSeeder.php
+++ b/src/database/seeds/local/UserSeeder.php
@@ -136,8 +136,6 @@
 
         $joe->setAliases(['joe.monster@kolab.org']);
 
-        // factory(User::class, 10)->create();
-
         $jeroen = User::create(
             [
                 'email' => 'jeroen@jeroen.jeroen',
diff --git a/src/phpunit.xml b/src/phpunit.xml
--- a/src/phpunit.xml
+++ b/src/phpunit.xml
@@ -25,13 +25,13 @@
             <directory suffix="Test.php">tests/Browser</directory>
         </testsuite>
     </testsuites>
-    <filter>
-        <whitelist processUncoveredFilesFromWhitelist="true">
+    <coverage processUncoveredFiles="true">
+        <include>
             <directory suffix=".php">./app</directory>
-        </whitelist>
-    </filter>
+        </include>
+    </coverage>
     <logging>
-        <log type="coverage-html" target="./tests/report/" lowUpperBound="35" highLowerBound="70"/>
+        <testdoxHtml outputFile="./tests/report/testdox.html" />
     </logging>
     <php>
         <server name="APP_ENV" value="testing"/>
diff --git a/src/tests/Browser.php b/src/tests/Browser.php
--- a/src/tests/Browser.php
+++ b/src/tests/Browser.php
@@ -19,8 +19,9 @@
     {
         $element = $this->resolver->findOrFail($selector);
         $value   = (string) $element->getAttribute($attribute);
+        $error   = "No expected text in [$selector][$attribute]. Found: $value";
 
-        Assert::assertRegExp($regexp, $value, "No expected text in [$selector][$attribute]. Found: $value");
+        Assert::assertMatchesRegularExpression($regexp, $value, $error);
 
         return $this;
     }
@@ -149,7 +150,7 @@
     {
         $element = $this->resolver->findOrFail($selector);
 
-        Assert::assertRegExp($regexp, $element->getText(), "No expected text in [$selector]");
+        Assert::assertMatchesRegularExpression($regexp, $element->getText(), "No expected text in [$selector]");
 
         return $this;
     }
diff --git a/src/tests/Feature/Controller/OpenViduTest.php b/src/tests/Feature/Controller/OpenViduTest.php
--- a/src/tests/Feature/Controller/OpenViduTest.php
+++ b/src/tests/Feature/Controller/OpenViduTest.php
@@ -63,7 +63,7 @@
 
         $this->assertSame(1, $json['count']);
         $this->assertCount(1, $json['list']);
-        $this->assertRegExp('/^[0-9a-z-]{11}$/', $json['list'][0]['name']);
+        $this->assertMatchesRegularExpression('/^[0-9a-z-]{11}$/', $json['list'][0]['name']);
     }
 
     /**
diff --git a/src/tests/Feature/Controller/PaymentsMollieTest.php b/src/tests/Feature/Controller/PaymentsMollieTest.php
--- a/src/tests/Feature/Controller/PaymentsMollieTest.php
+++ b/src/tests/Feature/Controller/PaymentsMollieTest.php
@@ -137,7 +137,7 @@
         $json = $response->json();
 
         $this->assertSame('success', $json['status']);
-        $this->assertRegExp('|^https://www.mollie.com|', $json['redirectUrl']);
+        $this->assertMatchesRegularExpression('|^https://www.mollie.com|', $json['redirectUrl']);
 
         // Assert the proper payment amount has been used
         $payment = Payment::where('id', $json['id'])->first();
@@ -366,7 +366,7 @@
         $json = $response->json();
 
         $this->assertSame('success', $json['status']);
-        $this->assertRegExp('|^https://www.mollie.com|', $json['redirectUrl']);
+        $this->assertMatchesRegularExpression('|^https://www.mollie.com|', $json['redirectUrl']);
 
         $wallet = $user->wallets()->first();
         $payments = Payment::where('wallet_id', $wallet->id)->get();
diff --git a/src/tests/Feature/Controller/PaymentsStripeTest.php b/src/tests/Feature/Controller/PaymentsStripeTest.php
--- a/src/tests/Feature/Controller/PaymentsStripeTest.php
+++ b/src/tests/Feature/Controller/PaymentsStripeTest.php
@@ -129,7 +129,7 @@
         $json = $response->json();
 
         $this->assertSame('success', $json['status']);
-        $this->assertRegExp('|^cs_test_|', $json['id']);
+        $this->assertMatchesRegularExpression('|^cs_test_|', $json['id']);
 
         // Assert the proper payment amount has been used
         // Stripe in 'setup' mode does not allow to set the amount
@@ -320,7 +320,7 @@
         $json = $response->json();
 
         $this->assertSame('success', $json['status']);
-        $this->assertRegExp('|^cs_test_|', $json['id']);
+        $this->assertMatchesRegularExpression('|^cs_test_|', $json['id']);
 
         $wallet = $user->wallets()->first();
         $payments = Payment::where('wallet_id', $wallet->id)->get();
diff --git a/src/tests/Feature/Controller/Reseller/PaymentsMollieTest.php b/src/tests/Feature/Controller/Reseller/PaymentsMollieTest.php
--- a/src/tests/Feature/Controller/Reseller/PaymentsMollieTest.php
+++ b/src/tests/Feature/Controller/Reseller/PaymentsMollieTest.php
@@ -82,7 +82,7 @@
         $json = $response->json();
 
         $this->assertSame('success', $json['status']);
-        $this->assertRegExp('|^https://www.mollie.com|', $json['redirectUrl']);
+        $this->assertMatchesRegularExpression('|^https://www.mollie.com|', $json['redirectUrl']);
 
         // Assert the proper payment amount has been used
         $payment = Payment::where('id', $json['id'])->first();
@@ -201,7 +201,7 @@
         $json = $response->json();
 
         $this->assertSame('success', $json['status']);
-        $this->assertRegExp('|^https://www.mollie.com|', $json['redirectUrl']);
+        $this->assertMatchesRegularExpression('|^https://www.mollie.com|', $json['redirectUrl']);
     }
 
     /**
diff --git a/src/tests/Feature/Controller/WalletsTest.php b/src/tests/Feature/Controller/WalletsTest.php
--- a/src/tests/Feature/Controller/WalletsTest.php
+++ b/src/tests/Feature/Controller/WalletsTest.php
@@ -71,13 +71,13 @@
         $wallet->balance = 990;
         $notice = $method->invoke($controller, $wallet);
 
-        $this->assertRegExp('/\((1 month|4 weeks)\)/', $notice);
+        $this->assertMatchesRegularExpression('/\((1 month|4 weeks)\)/', $notice);
 
         // test "2 months"
         $wallet->balance = 990 * 2.6;
         $notice = $method->invoke($controller, $wallet);
 
-        $this->assertRegExp('/\(2 months 2 weeks\)/', $notice);
+        $this->assertMatchesRegularExpression('/\(2 months 2 weeks\)/', $notice);
 
         // Change locale to make sure the text is localized by Carbon
         \app()->setLocale('de');
@@ -86,7 +86,7 @@
         $wallet->balance = 990 * 23.5;
         $notice = $method->invoke($controller, $wallet);
 
-        $this->assertRegExp('/\(1 Jahr 11 Monate\)/', $notice);
+        $this->assertMatchesRegularExpression('/\(1 Jahr 11 Monate\)/', $notice);
 
         // Old entitlements, 100% discount
         $this->backdateEntitlements($wallet->entitlements, Carbon::now()->subDays(40));
diff --git a/src/tests/Feature/GroupTest.php b/src/tests/Feature/GroupTest.php
--- a/src/tests/Feature/GroupTest.php
+++ b/src/tests/Feature/GroupTest.php
@@ -110,7 +110,7 @@
         $group = Group::create(['email' => 'GROUP-test@kolabnow.com']);
 
         $this->assertSame('group-test@kolabnow.com', $group->email);
-        $this->assertRegExp('/^[0-9]{1,20}$/', $group->id);
+        $this->assertMatchesRegularExpression('/^[0-9]{1,20}$/', $group->id);
         $this->assertSame([], $group->members);
         $this->assertTrue($group->isNew());
         $this->assertTrue($group->isActive());
diff --git a/src/tests/Feature/Jobs/WalletCheckTest.php b/src/tests/Feature/Jobs/WalletCheckTest.php
--- a/src/tests/Feature/Jobs/WalletCheckTest.php
+++ b/src/tests/Feature/Jobs/WalletCheckTest.php
@@ -110,8 +110,8 @@
 
         $wallet->refresh();
         $today_regexp = '/' . Carbon::now()->toDateString() . ' [0-9]{2}:[0-9]{2}:[0-9]{2}/';
-        $this->assertRegExp($today_regexp, $wallet->getSetting('balance_negative_since'));
-        $this->assertRegExp($today_regexp, $wallet->getSetting('balance_warning_initial'));
+        $this->assertMatchesRegularExpression($today_regexp, $wallet->getSetting('balance_negative_since'));
+        $this->assertMatchesRegularExpression($today_regexp, $wallet->getSetting('balance_warning_initial'));
     }
 
     /**
diff --git a/src/tests/Unit/DomainTest.php b/src/tests/Unit/DomainTest.php
--- a/src/tests/Unit/DomainTest.php
+++ b/src/tests/Unit/DomainTest.php
@@ -119,11 +119,11 @@
 
         $hash_code = $domain->hash();
 
-        $this->assertRegExp('/^[a-f0-9]{32}$/', $hash_code);
+        $this->assertMatchesRegularExpression('/^[a-f0-9]{32}$/', $hash_code);
 
         $hash_text = $domain->hash(Domain::HASH_TEXT);
 
-        $this->assertRegExp('/^kolab-verify=[a-f0-9]{32}$/', $hash_text);
+        $this->assertMatchesRegularExpression('/^kolab-verify=[a-f0-9]{32}$/', $hash_text);
 
         $this->assertSame($hash_code, str_replace('kolab-verify=', '', $hash_text));
 
diff --git a/src/tests/Unit/UserTest.php b/src/tests/Unit/UserTest.php
--- a/src/tests/Unit/UserTest.php
+++ b/src/tests/Unit/UserTest.php
@@ -19,7 +19,7 @@
         $ssh512 = "{SSHA512}7iaw3Ur350mqGo7jwQrpkj9hiYB3Lkc/iBml1JQODbJ"
             . "6wYX4oOHV+E+IvIh/1nsUNzLDBMxfqa2Ob1f1ACio/w==";
 
-        $this->assertRegExp('/^\$2y\$12\$[0-9a-zA-Z\/.]{53}$/', $user->password);
+        $this->assertMatchesRegularExpression('/^\$2y\$12\$[0-9a-zA-Z\/.]{53}$/', $user->password);
         $this->assertSame($ssh512, $user->password_ldap);
     }
 
@@ -35,7 +35,7 @@
         $ssh512 = "{SSHA512}7iaw3Ur350mqGo7jwQrpkj9hiYB3Lkc/iBml1JQODbJ"
             . "6wYX4oOHV+E+IvIh/1nsUNzLDBMxfqa2Ob1f1ACio/w==";
 
-        $this->assertRegExp('/^\$2y\$12\$[0-9a-zA-Z\/.]{53}$/', $user->password);
+        $this->assertMatchesRegularExpression('/^\$2y\$12\$[0-9a-zA-Z\/.]{53}$/', $user->password);
         $this->assertSame($ssh512, $user->password_ldap);
     }