diff --git a/php-packages/testing/.github/workflows/test.yml b/php-packages/testing/.github/workflows/test.yml
new file mode 100644
index 000000000..b7ba28c30
--- /dev/null
+++ b/php-packages/testing/.github/workflows/test.yml
@@ -0,0 +1,83 @@
+name: Tests
+
+on: [push, pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    defaults:
+      run:
+        shell: bash
+        working-directory: tests
+
+    strategy:
+      matrix:
+        php: [7.3, 7.4, '8.0']
+        service: ['mysql:5.7', mariadb]
+        prefix: ['', flarum_]
+
+        include:
+          - service: 'mysql:5.7'
+            db: MySQL
+          - service: mariadb
+            db: MariaDB
+          - prefix: flarum_
+            prefixStr: (prefix)
+
+        exclude:
+          - php: 7.3
+            service: 'mysql:5.7'
+            prefix: flarum_
+          - php: 7.3
+            service: mariadb
+            prefix: flarum_
+          - php: 8.0
+            service: 'mysql:5.7'
+            prefix: flarum_
+          - php: 8.0
+            service: mariadb
+            prefix: flarum_
+
+    services:
+      mysql:
+        image: ${{ matrix.service }}
+        ports:
+          - 13306:3306
+
+    name: 'PHP ${{ matrix.php }} / ${{ matrix.db }} ${{ matrix.prefixStr }}'
+
+    steps:
+      - uses: actions/checkout@master
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          coverage: xdebug
+          extensions: curl, dom, gd, json, mbstring, openssl, pdo_mysql, tokenizer, zip
+          tools: phpunit, composer:v2
+
+      # The authentication alter is necessary because newer mysql versions use the `caching_sha2_password` driver,
+      # which isn't supported prior to PHP7.4
+      # When we drop support for PHP7.3, we should remove this from the setup.
+      - name: Create MySQL Database
+        run: |
+          sudo systemctl start mysql
+          mysql -uroot -proot -e 'CREATE DATABASE flarum_test;' --port 13306
+          mysql -uroot -proot -e "ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'root';" --port 13306
+
+      - name: Install Composer dependencies
+        run: composer install
+
+      - name: Setup Composer tests
+        run: composer test:setup
+        env:
+          DB_PORT: 13306
+          DB_PASSWORD: root
+          DB_PREFIX: ${{ matrix.prefix }}
+
+      - name: Run Composer tests
+        run: composer test
+        env:
+          COMPOSER_PROCESS_TIMEOUT: 600
diff --git a/php-packages/testing/composer.json b/php-packages/testing/composer.json
index eb29a6161..44ea9e07f 100644
--- a/php-packages/testing/composer.json
+++ b/php-packages/testing/composer.json
@@ -20,6 +20,11 @@
             "Flarum\\Testing\\": "src/"
         }
     },
+    "autoload-dev": {
+        "psr-4": {
+            "Flarum\\Testing\\Tests\\": "src/tests/"
+        }
+    },
     "extra": {
         "branch-alias": {
             "dev-master": "0.1.x-dev"
diff --git a/php-packages/testing/src/integration/Extend/SetSettingsBeforeBoot.php b/php-packages/testing/src/integration/Extend/SetSettingsBeforeBoot.php
new file mode 100644
index 000000000..51957b19a
--- /dev/null
+++ b/php-packages/testing/src/integration/Extend/SetSettingsBeforeBoot.php
@@ -0,0 +1,32 @@
+<?php
+
+namespace Flarum\Testing\integration\Extend;
+
+use Flarum\Extend\ExtenderInterface;
+use Flarum\Extension\Extension;
+use Flarum\Settings\SettingsRepositoryInterface;
+use Illuminate\Contracts\Container\Container;
+
+class SetSettingsBeforeBoot implements ExtenderInterface
+{
+    /**
+     * IDs of extensions to boot
+     */
+    protected $settings;
+
+    public function __construct($settings)
+    {
+        $this->settings = $settings;
+    }
+
+    public function extend(Container $container, Extension $extension = null)
+    {
+        if (count($this->settings)) {
+            $settings = $container->make(SettingsRepositoryInterface::class);
+            
+            foreach ($this->settings as $key => $value) {
+                $settings->set($key, $value);
+            }
+        }
+    }
+}
diff --git a/php-packages/testing/src/integration/TestCase.php b/php-packages/testing/src/integration/TestCase.php
index bba228879..d54a90a37 100644
--- a/php-packages/testing/src/integration/TestCase.php
+++ b/php-packages/testing/src/integration/TestCase.php
@@ -14,6 +14,7 @@ use Flarum\Foundation\Config;
 use Flarum\Foundation\InstalledSite;
 use Flarum\Foundation\Paths;
 use Flarum\Testing\integration\Extend\OverrideExtensionManagerForTests;
+use Flarum\Testing\integration\Extend\SetSettingsBeforeBoot;
 use Illuminate\Database\ConnectionInterface;
 use Laminas\Diactoros\ServerRequest;
 use Psr\Http\Message\ResponseInterface;
@@ -59,7 +60,8 @@ abstract class TestCase extends \PHPUnit\Framework\TestCase
             );
 
             $extenders = array_merge([
-                new OverrideExtensionManagerForTests($this->extensions)
+                new OverrideExtensionManagerForTests($this->extensions),
+                new SetSettingsBeforeBoot($this->settings),
             ], $this->extenders);
 
             $site->extendWith($extenders);
@@ -79,6 +81,13 @@ abstract class TestCase extends \PHPUnit\Framework\TestCase
      */
     protected $extenders = [];
 
+    /**
+     * Each argument should be an instance of an extender that should
+     * be applied at application boot.
+     * 
+     * Note that this method will have no effect if called after the
+     * application is booted.
+     */
     protected function extend(ExtenderInterface ...$extenders)
     {
         $this->extenders = array_merge($this->extenders, $extenders);
@@ -89,11 +98,40 @@ abstract class TestCase extends \PHPUnit\Framework\TestCase
      */
     protected $extensions = [];
 
+    /**
+     * Each argument should be an ID of an extension to be enabled.
+     * Extensions other than the one currently being tested must be
+     * listed in this extension's `composer.json` under `require` or
+     * `require-dev`.
+     * 
+     * Note that this method will have no effect if called after the
+     * application is booted.
+     */
     protected function extension(string ...$extensions)
     {
         $this->extensions = array_merge($this->extensions, $extensions);
     }
 
+    /**
+     * @var string[]
+     */
+    protected $settings = [];
+
+    /**
+     * Some settings are used during application boot, so setting
+     * them via `prepareDatabase` will be too late for the desired
+     * effect. For instance, in core the active display name driver
+     * is configured based on the `display_name_driver` setting.
+     * That setting should be registered using this method.
+     * 
+     * Note that this method will have no effect if called after the
+     * application is booted.
+     */
+    protected function setting(string $key, string $value)
+    {
+        $this->settings[$key] = $value;
+    }
+
     /**
      * @var RequestHandlerInterface
      */
diff --git a/php-packages/testing/tests/.gitignore b/php-packages/testing/tests/.gitignore
new file mode 100644
index 000000000..208a59913
--- /dev/null
+++ b/php-packages/testing/tests/.gitignore
@@ -0,0 +1 @@
+vendor/*
\ No newline at end of file
diff --git a/php-packages/testing/tests/README.md b/php-packages/testing/tests/README.md
new file mode 100644
index 000000000..ec93c967f
--- /dev/null
+++ b/php-packages/testing/tests/README.md
@@ -0,0 +1 @@
+A minimal extension skeleton to test the flarum/testing package.
\ No newline at end of file
diff --git a/php-packages/testing/tests/composer.json b/php-packages/testing/tests/composer.json
new file mode 100644
index 000000000..58baed651
--- /dev/null
+++ b/php-packages/testing/tests/composer.json
@@ -0,0 +1,35 @@
+{
+  "name": "flarum/testing-tests",
+  "description": "Minimal extension to test the flarum/testing package",
+  "type": "flarum-extension",
+  "require": {
+    "flarum/core": "^0.1.0-beta.16"
+  },
+  "require-dev": {
+    "flarum/testing": "*@dev"
+  },
+  "autoload-dev": {
+    "psr-4": {
+      "Flarum\\Testing\\Tests\\": "tests/"
+    }
+  },
+  "scripts": {
+    "test": [
+      "@test:unit",
+      "@test:integration"
+    ],
+    "test:unit": "phpunit -c tests/phpunit.unit.xml",
+    "test:integration": "phpunit -c tests/phpunit.integration.xml",
+    "test:setup": "@php tests/integration/setup.php"
+  },
+  "scripts-descriptions": {
+    "test": "Runs all tests.",
+    "test:unit": "Runs all unit tests.",
+    "test:integration": "Runs all integration tests.",
+    "test:setup": "Sets up a database for use with integration tests. Execute this only once."
+  },
+  "repositories": [{
+      "type": "path",
+      "url": "../"
+    }]
+}
diff --git a/php-packages/testing/tests/extend.php b/php-packages/testing/tests/extend.php
new file mode 100644
index 000000000..8ece8c036
--- /dev/null
+++ b/php-packages/testing/tests/extend.php
@@ -0,0 +1,20 @@
+<?php
+
+/*
+ * This file is part of flarum/testing-tests.
+ *
+ * Copyright (c) 2021 .
+ *
+ * For the full copyright and license information, please view the LICENSE.md
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Testing;
+
+use Flarum\Extend;
+
+return [
+    
+    
+    
+];
diff --git a/php-packages/testing/tests/tests/.phpunit.result.cache b/php-packages/testing/tests/tests/.phpunit.result.cache
new file mode 100644
index 000000000..05fbec964
--- /dev/null
+++ b/php-packages/testing/tests/tests/.phpunit.result.cache
@@ -0,0 +1 @@
+C:37:"PHPUnit\Runner\DefaultTestResultCache":219:{a:2:{s:7:"defects";a:1:{s:74:"Flarum\Testing\Tests\integration\TestCaseTest::can_add_settings_via_method";i:4;}s:5:"times";a:1:{s:74:"Flarum\Testing\Tests\integration\TestCaseTest::can_add_settings_via_method";d:0.09;}}}
\ No newline at end of file
diff --git a/php-packages/testing/tests/tests/fixtures/.gitkeep b/php-packages/testing/tests/tests/fixtures/.gitkeep
new file mode 100644
index 000000000..e69de29bb
diff --git a/php-packages/testing/tests/tests/integration/TestCaseTest.php b/php-packages/testing/tests/tests/integration/TestCaseTest.php
new file mode 100644
index 000000000..4aa709da1
--- /dev/null
+++ b/php-packages/testing/tests/tests/integration/TestCaseTest.php
@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Testing\Tests\integration;
+
+use Flarum\Settings\SettingsRepositoryInterface;
+use Flarum\Testing\integration\TestCase;
+
+class TestCaseTest extends TestCase
+{
+    /**
+     * @test
+     */
+    public function can_add_settings_via_method()
+    {
+        $this->setting('hello', 'world');
+        $this->setting('display_name_driver', 'something_other_than_username');
+
+        $settings = $this->app()->getContainer()->make(SettingsRepositoryInterface::class);
+
+        $this->assertEquals('world', $settings->get('hello'));
+        $this->assertEquals('something_other_than_username', $settings->get('display_name_driver'));
+    }
+}
\ No newline at end of file
diff --git a/php-packages/testing/tests/tests/integration/setup.php b/php-packages/testing/tests/tests/integration/setup.php
new file mode 100644
index 000000000..67039c083
--- /dev/null
+++ b/php-packages/testing/tests/tests/integration/setup.php
@@ -0,0 +1,16 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+use Flarum\Testing\integration\Setup\SetupScript;
+
+require __DIR__.'/../../vendor/autoload.php';
+
+$setup = new SetupScript();
+
+$setup->run();
diff --git a/php-packages/testing/tests/tests/phpunit.integration.xml b/php-packages/testing/tests/tests/phpunit.integration.xml
new file mode 100644
index 000000000..23afc237d
--- /dev/null
+++ b/php-packages/testing/tests/tests/phpunit.integration.xml
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd"
+    backupGlobals="false"
+    backupStaticAttributes="false"
+    colors="true"
+    convertErrorsToExceptions="true"
+    convertNoticesToExceptions="true"
+    convertWarningsToExceptions="true"
+    processIsolation="true"
+    stopOnFailure="false"
+>
+    <coverage processUncoveredFiles="true">
+        <include>
+            <directory suffix=".php">../src/</directory>
+        </include>
+    </coverage>
+    <testsuites>
+        <testsuite name="Flarum Integration Tests">
+            <directory suffix="Test.php">./integration</directory>
+        </testsuite>
+    </testsuites>
+</phpunit>
diff --git a/php-packages/testing/tests/tests/phpunit.unit.xml b/php-packages/testing/tests/tests/phpunit.unit.xml
new file mode 100644
index 000000000..d3a4a3e3d
--- /dev/null
+++ b/php-packages/testing/tests/tests/phpunit.unit.xml
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd"
+    backupGlobals="false"
+    backupStaticAttributes="false"
+    colors="true"
+    convertErrorsToExceptions="true"
+    convertNoticesToExceptions="true"
+    convertWarningsToExceptions="true"
+    processIsolation="false"
+    stopOnFailure="false"
+>
+    <coverage processUncoveredFiles="true">
+        <include>
+            <directory suffix=".php">../src/</directory>
+        </include>
+    </coverage>
+    <testsuites>
+        <testsuite name="Flarum Unit Tests">
+            <directory suffix="Test.php">./unit</directory>
+        </testsuite>
+    </testsuites>
+    <listeners>
+        <listener class="\Mockery\Adapter\Phpunit\TestListener" />
+    </listeners>
+</phpunit>
diff --git a/php-packages/testing/tests/tests/unit/.gitkeep b/php-packages/testing/tests/tests/unit/.gitkeep
new file mode 100644
index 000000000..e69de29bb