diff --git a/.docker/Dockerfile.test b/.docker/Dockerfile.test
index b2458c7e..28c81718 100644
--- a/.docker/Dockerfile.test
+++ b/.docker/Dockerfile.test
@@ -30,8 +30,11 @@ COPY .docker/images/govcms/mariadb-client.cnf /etc/my.cnf.d
 # Copy application files from the 'cli' stage to the current stage
 COPY --from=cli /app /app
 
+# Install dev dependencies (e.g. PHPUnit) excluded from the CLI image.
+RUN composer install --dev
+
 # Copy PHPUnit configuration and test files
-COPY --from=govcmstesting/tests:3.2.3-php8.3 /tests /app/tests
+COPY tests /app/tests
 
 # Set an environment variable for the webroot path
 ENV WEBROOT=web
diff --git a/composer.json b/composer.json
index 5fab2017..0f589a86 100644
--- a/composer.json
+++ b/composer.json
@@ -22,7 +22,18 @@
     },
     "require-dev": {
         "drupal/core-dev": "^11.0",
-        "palantirnet/drupal-rector": "^0.20.3"
+        "behat/behat": "^3.32",
+        "dealerdirect/phpcodesniffer-composer-installer": "^1.0",
+        "drevops/behat-format-progress-fail": "^1.5",
+        "drevops/behat-screenshot": "^2.6",
+        "drevops/behat-steps": "^3.0",
+        "drupal/coder": "^8.3",
+        "drupal/drupal-extension": "^6.0",
+        "palantirnet/drupal-rector": "^0.20",
+        "php-parallel-lint/php-console-highlighter": "^1.0",
+        "php-parallel-lint/php-parallel-lint": "^1.3",
+        "phpmd/phpmd": "^2.15",
+        "weitzman/drupal-test-traits": "^2.0"
     },
     "conflict": {
         "drupal/drupal": "*"