diff --git a/.github/workflows/backend.yml b/.github/workflows/backend.yml
new file mode 100644
index 0000000..624436f
--- /dev/null
+++ b/.github/workflows/backend.yml
@@ -0,0 +1,11 @@
+name: FoF Discussion Language PHP
+
+on: [workflow_dispatch, push, pull_request]
+
+jobs:
+  run:
+    uses: flarum/framework/.github/workflows/REUSABLE_backend.yml@main
+    with:
+      enable_backend_testing: true
+
+      backend_directory: .
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
deleted file mode 100644
index a5d4493..0000000
--- a/.github/workflows/build.yml
+++ /dev/null
@@ -1,32 +0,0 @@
-name: JavaScript
-
-on:
-  push:
-    branches:
-      - master
-
-jobs:
-  build:
-    name: JS / Build
-    runs-on: ubuntu-latest
-
-    steps:
-      - name: Check out code
-        uses: actions/checkout@v3
-
-      - name: Restore npm cache
-        uses: actions/cache@v3
-        with:
-          path: ~/.npm
-          key: ${{ runner.os }}-node-${{ hashFiles('js/package-lock.json') }}
-          restore-keys: |
-            ${{ runner.os }}-node-
-
-      # Our action will install npm, cd into `./js`, run `npm run build` and
-      # `npm run build-typings`, then commit and upload any changes
-      - name: Build production JS
-        uses: flarum/action-build@v3
-        with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
-          build_script: build
-          package_manager: npm
diff --git a/.github/workflows/frontend.yml b/.github/workflows/frontend.yml
new file mode 100644
index 0000000..6d6cc29
--- /dev/null
+++ b/.github/workflows/frontend.yml
@@ -0,0 +1,19 @@
+name: FoF Discussion Language JS
+
+on: [workflow_dispatch, push, pull_request]
+
+jobs:
+  run:
+    uses: flarum/framework/.github/workflows/REUSABLE_frontend.yml@main
+    with:
+      enable_bundlewatch: false
+      enable_prettier: true
+      enable_typescript: true
+
+      frontend_directory: ./js
+      backend_directory: .
+      js_package_manager: npm
+      main_git_branch: master
+
+    secrets:
+      bundlewatch_github_token: ${{ secrets.BUNDLEWATCH_GITHUB_TOKEN }}
diff --git a/.gitignore b/.gitignore
index 04fdede..3b19fb0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@ js/dist
 js/node_modules
 vendor
 composer.lock
+.phpunit.result.cache
diff --git a/composer.json b/composer.json
index 5c0dd61..6383e18 100644
--- a/composer.json
+++ b/composer.json
@@ -1,67 +1,94 @@
 {
-  "name": "fof/discussion-language",
-  "description": "Specify the language a discussion is written in & sort by language",
-  "keywords": [
-    "flarum"
-  ],
-  "type": "flarum-extension",
-  "license": "MIT",
-  "support": {
-    "issues": "https://github.com/FriendsOfFlarum/discussion-language/issues",
-    "source": "https://github.com/FriendsOfFlarum/discussion-language",
-    "forum": "https://discuss.flarum.org/d/23702"
-  },
-  "homepage": "https://friendsofflarum.org",
-  "funding": [
-    {
-      "type": "website",
-      "url": "https://opencollective.com/fof/donate"
-    }
-  ],
-  "require": {
-    "flarum/core": "^1.8.1",
-    "rinvex/countries": "^6.1.2 || ^7.0.1 || ^8.1.0",
-    "league/csv": "^9.7",
-    "ianm/iso-639": "^1.0",
-    "flarum/tags": "*"
-  },
-  "authors": [
-    {
-      "name": "David Sevilla Martin",
-      "email": "me+fof@datitisev.me",
-      "role": "Developer"
+    "name": "fof/discussion-language",
+    "description": "Specify the language a discussion is written in & sort by language",
+    "keywords": [
+        "flarum"
+    ],
+    "type": "flarum-extension",
+    "license": "MIT",
+    "support": {
+        "issues": "https://github.com/FriendsOfFlarum/discussion-language/issues",
+        "source": "https://github.com/FriendsOfFlarum/discussion-language",
+        "forum": "https://discuss.flarum.org/d/23702"
     },
-    {
-      "name": "IanM",
-      "email": "ian@flarum.org",
-      "role": "Developer"
-    }
-  ],
-  "autoload": {
-    "psr-4": {
-      "FoF\\DiscussionLanguage\\": "src/"
-    }
-  },
-  "extra": {
-    "flarum-extension": {
-      "title": "FoF Discussion Language",
-      "category": "feature",
-      "icon": {
-        "name": "fas fa-language",
-        "backgroundColor": "#e74c3c",
-        "color": "#fff"
-      },
-      "optional-dependencies": [
-        "fof/byobu",
-        "fof/follow-tags"
-      ]
+    "homepage": "https://friendsofflarum.org",
+    "funding": [
+        {
+            "type": "website",
+            "url": "https://opencollective.com/fof/donate"
+        }
+    ],
+    "require": {
+        "flarum/core": "^1.8.1",
+        "rinvex/countries": "^6.1.2 || ^7.0.1 || ^8.1.0",
+        "league/csv": "^9.7",
+        "ianm/iso-639": "^1.0",
+        "flarum/tags": "*"
+    },
+    "authors": [
+        {
+            "name": "David Sevilla Martin",
+            "email": "me+fof@datitisev.me",
+            "role": "Developer"
+        },
+        {
+            "name": "IanM",
+            "email": "ian@flarum.org",
+            "role": "Developer"
+        }
+    ],
+    "autoload": {
+        "psr-4": {
+            "FoF\\DiscussionLanguage\\": "src/"
+        }
+    },
+    "extra": {
+        "flarum-extension": {
+            "title": "FoF Discussion Language",
+            "category": "feature",
+            "icon": {
+                "name": "fas fa-language",
+                "backgroundColor": "#e74c3c",
+                "color": "#fff"
+            },
+            "optional-dependencies": [
+                "fof/byobu",
+                "fof/follow-tags"
+            ]
+        },
+        "flagrow": {
+            "discuss": "https://discuss.flarum.org/d/23702"
+        },
+        "flarum-cli": {
+            "modules": {
+                "githubActions": true,
+                "backendTesting": true
+            }
+        }
+    },
+    "require-dev": {
+        "fof/byobu": "*",
+        "fof/follow-tags": "*",
+        "flarum/testing": "^1.0.0"
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "FoF\\DiscussionLanguage\\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"
     },
-    "flagrow": {
-      "discuss": "https://discuss.flarum.org/d/23702"
+    "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."
     }
-  },
-  "require-dev": {
-    "fof/byobu": "*",
-    "fof/follow-tags": "*"
-  }
 }
diff --git a/migrations/2023_09_12_000000_add_language_id_to_tag_user_table.php b/migrations/2023_09_12_000000_add_language_id_to_tag_user_table.php
index 174d611..e36c7d4 100644
--- a/migrations/2023_09_12_000000_add_language_id_to_tag_user_table.php
+++ b/migrations/2023_09_12_000000_add_language_id_to_tag_user_table.php
@@ -14,12 +14,14 @@
 
 return [
     'up' => function (Builder $schema) {
-        $schema->table('tag_user', function (Blueprint $table) {
-            $table->integer('dl_language_id')->unsigned()->nullable();
+        $schema->table('tag_user', function (Blueprint $table) use ($schema) {
+            if (!$schema->hasColumn('tag_user', 'dl_language_id')) {
+                $table->integer('dl_language_id')->unsigned()->nullable();
 
-            $table->foreign('dl_language_id')->references('id')->on('discussion_languages')->onDelete('set null');
+                $table->foreign('dl_language_id')->references('id')->on('discussion_languages')->onDelete('set null');
+            }
 
-            $table->index(['user_id', 'subscription', 'dl_language_id']);
+            $table->index(['user_id', 'dl_language_id']);
             $table->index(['dl_language_id']);
         });
     },
@@ -29,7 +31,7 @@
             $table->dropForeign(['dl_language_id']);
 
             $table->dropIndex(['dl_language_id']);
-            $table->dropIndex(['user_id', 'subscription', 'dl_language_id']);
+            $table->dropIndex(['user_id', 'dl_language_id']);
 
             $table->dropColumn('dl_language_id');
         });
diff --git a/tests/fixtures/.gitkeep b/tests/fixtures/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/tests/integration/api/CreateLanguageTest.php b/tests/integration/api/CreateLanguageTest.php
new file mode 100644
index 0000000..625c704
--- /dev/null
+++ b/tests/integration/api/CreateLanguageTest.php
@@ -0,0 +1,83 @@
+<?php
+
+/*
+ * This file is part of fof/discussion-language.
+ *
+ * Copyright (c) FriendsOfFlarum.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace FoF\DiscussionLanguage\tests\integration\api;
+
+use Flarum\Testing\integration\RetrievesAuthorizedUsers;
+use Flarum\Testing\integration\TestCase;
+
+class CreateLanguageTest extends TestCase
+{
+    use RetrievesAuthorizedUsers;
+
+    public function setUp(): void
+    {
+        parent::setUp();
+
+        $this->extension('flarum-tags');
+        $this->extension('fof-discussion-language');
+
+        $this->prepareDatabase([
+            'users' => [
+                $this->normalUser(),
+            ],
+        ]);
+    }
+
+    /**
+     * @test
+     */
+    public function non_admin_cannot_create_language()
+    {
+        $response = $this->send(
+            $this->request('POST', '/api/fof/discussion-language', [
+                'json' => [
+                    'data' => [
+                        'attributes' => [
+                            'country' => 'Test Country',
+                            'code'    => 'test',
+                        ],
+                    ],
+                ],
+                'authenticatedAs' => 2,
+            ])
+        );
+
+        $this->assertEquals(403, $response->getStatusCode());
+    }
+
+    /**
+     * @test
+     */
+    public function admin_can_create_language()
+    {
+        $response = $this->send(
+            $this->request('POST', '/api/fof/discussion-language', [
+                'json' => [
+                    'data' => [
+                        'attributes' => [
+                            'country' => 'Test Country',
+                            'code'    => 'test',
+                        ],
+                    ],
+                ],
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        $this->assertEquals(201, $response->getStatusCode());
+
+        $data = json_decode($response->getBody()->getContents(), true);
+
+        $this->assertEquals('Test Country', $data['data']['attributes']['country']);
+        $this->assertEquals('test', $data['data']['attributes']['code']);
+    }
+}
diff --git a/tests/integration/setup.php b/tests/integration/setup.php
new file mode 100644
index 0000000..f8bfb54
--- /dev/null
+++ b/tests/integration/setup.php
@@ -0,0 +1,18 @@
+<?php
+
+/*
+ * This file is part of fof/discussion-language.
+ *
+ * Copyright (c) FriendsOfFlarum.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+use Flarum\Testing\integration\Setup\SetupScript;
+
+require __DIR__.'/../../vendor/autoload.php';
+
+$setup = new SetupScript();
+
+$setup->run();
diff --git a/tests/phpunit.integration.xml b/tests/phpunit.integration.xml
new file mode 100644
index 0000000..90fbbff
--- /dev/null
+++ b/tests/phpunit.integration.xml
@@ -0,0 +1,25 @@
+<?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>
+             <exclude>./integration/tmp</exclude>
+        </testsuite>
+    </testsuites>
+</phpunit>
diff --git a/tests/phpunit.unit.xml b/tests/phpunit.unit.xml
new file mode 100644
index 0000000..d3a4a3e
--- /dev/null
+++ b/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/tests/unit/.gitkeep b/tests/unit/.gitkeep
new file mode 100644
index 0000000..e69de29