You can install Drupal website of your own to work with Behat Drupal Extension and Mink. Follow below steps for same:
Step 1: Open Acquia Dev Desktop and Click on + icon at the bottom.
Step 2: Select New Drupal Site...
Step 3: Click on install for Latest version
Step 4: Enter required detail and name for your site and database.
Step 5: Click on Local Site link
Step 6: Select Demo: Umami Food Magazine. This is good for Behat practice.
Step 7: Enter required detail. Save username and password.
Step 8: Your site is ready.