diff --git a/tests/Unit/README.md b/tests/Unit/README.md
index 39f0a9d6e13b7..a72eee4129c0d 100644
--- a/tests/Unit/README.md
+++ b/tests/Unit/README.md
@@ -8,4 +8,18 @@ When you are checking out the current development branch of 4.0 and run `compose
 
 1. Checkout the current Joomla 4.0 development branch from Github. (https://github.com/joomla/joomla-cms.git Branch `4.0-dev`)
 2. Run `composer install` in the root of your checkout.
-3. Run `libraries/vendor/bin/phpunit`.
+3. Add the file `joomla-cms/phpunit-xml` depending on your environment. You can use the files `joomla-cms/phpunit.xml.dist` and/or `joomla-cms/phpunit-pgsql.xml.dist` as an example.
+
+```
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit bootstrap="tests/Unit/bootstrap.php" colors="false">
+...
+	<php>
+		...
+		<const name="JTEST_DB_NAME" value="YOUR_DB_NAME" />
+		<const name="JTEST_DB_USER" value="YOUR_USER" />
+		<const name="JTEST_DB_PASSWORD" value="YOUR_PASSWORD" />
+	</php>
+</phpunit>
+```
+4. Run `libraries/vendor/bin/phpunit`