Add required git dependency.

.travis.yml

@@ -35,6 +35,9 @@ script:
   # Run container in detached state.
   - 'sudo docker run --detach --volume="${PWD}":/etc/ansible/roles/role_under_test:ro ${run_opts} ${repository}:${version} "${init}" > "${container_id}"'
 
+  # Install dependencies.
+  - 'sudo docker exec "$(cat ${container_id})" ansible-galaxy install -r /etc/ansible/roles/role_under_test/tests/requirements.yml'
+
   # Ansible syntax check.
   - 'sudo docker exec --tty "$(cat ${container_id})" env TERM=xterm ansible-playbook /etc/ansible/roles/role_under_test/tests/test.yml --syntax-check'
 

tests/requirements.yml

@@ -0,0 +1,2 @@
+---
+- src: geerlingguy.git

tests/test.yml

@@ -2,4 +2,5 @@
 - hosts: all
 
   roles:
+    - geerlingguy.git
     - role_under_test