diff --git a/README-testing.md b/README-testing.md
index 7a7c5b593..4238b6e48 100644
--- a/README-testing.md
+++ b/README-testing.md
@@ -29,8 +29,14 @@ To mirror the CI environment on your machine:
    docker compose -f docker-compose-test.yml up -d
    ```
 
-3. **Run the suites:**
-   * **PHPUnit:** `docker exec -it opencats_test_php ./vendor/bin/phpunit src/OpenCATS/Tests/IntegrationTests`
+3. **Install PHP dependencies (Composer):**
+   ```bash
+   docker run --rm -v "$(pwd)/..":/app -w /app composer:2 composer install --no-interaction --prefer-dist --ignore-platform-reqs
+   ```
+
+4. **Run the suites:**
+   * **PHPUnit Unit Tests:** `docker exec -it opencats_test_php ./vendor/bin/phpunit src/OpenCATS/Tests/UnitTests`
+   * **PHPUnit Integration Tests:** `docker exec -it opencats_test_php ./vendor/bin/phpunit src/OpenCATS/Tests/IntegrationTests`
    * **Behat:** `docker exec -it opencats_test_php ./vendor/bin/behat -c ./test/behat.yml`
 
 ---
diff --git a/docker/docker-compose-test.yml b/docker/docker-compose-test.yml
index cbe6fb490..2d728bcd3 100644
--- a/docker/docker-compose-test.yml
+++ b/docker/docker-compose-test.yml
@@ -12,6 +12,7 @@ services:
     php:
       container_name: opencats_test_php
       image: opencats/php-base:7.2-fpm-alpine
+      working_dir: /var/www/public
       volumes_from:
         - opencatsdata