Add Molecule to Docker role (#5129)

* Add Molecule for container-engine/docker

* Add bootstrap-os to Molecule prepare stage

roles/container-engine/docker/molecule/default/tests/test_default.py

@@ -0,0 +1,19 @@
+import os
+
+import testinfra.utils.ansible_runner
+
+testinfra_hosts = testinfra.utils.ansible_runner.AnsibleRunner(
+    os.environ['MOLECULE_INVENTORY_FILE']).get_hosts('all')
+
+
+def test_docker_service(host):
+    docker = host.service("docker")
+    assert docker.is_running
+    assert docker.is_enabled
+
+
+def test_docker_run(host):
+    with host.sudo():
+        cmd = host.command("docker run hello-world")
+    assert cmd.rc == 0
+    assert "Hello from Docker!" in cmd.stdout