Automate the execution of all molecule scenarios (#17)

# Context

This PR implements the following [issue](#12).

# Acceptance criteria

- [ ] A Task task for running all Ansible Molecule scenarios has been introduced.
- [ ] A Task task for running selected Ansible Molecule scenarios has been introduced.
- [ ] `README.md` has been updated to provide correct guidance on executing Ansible Molecule scenarios.

Co-authored-by: emo <esimeonov@gmail.com>
Reviewed-on: #17

README.md

@@ -217,22 +217,12 @@ Navigate to the root folder of the local copy of this git repository.
 cd test_linux_containers
 ```
 
-Install locally a snapshot version of `theliberatededge.test_linux_containers`
-that will be used as the foundation for automated testing.
+Run the following task to execute all of the Ansible Molecule test scenarios
+in the project.
 
 ```
-LC_ALL=C.UTF-8 ansible-galaxy install -r requirements-test.yml --force
+LTE_CONTAINER_ROOT_PWD=<password> task test-all
 ```
 
-Execute all existing Ansible Molecule scenarios.
-
-```
-cd extensions
-```
-
-```
-LC_ALL=C.UTF-8 \
-LTE_CONTAINER_NAME=<container name> \
-LTE_CONTAINER_ROOT_PWD=<password> \
-    molecule test --all
-```
+`LTE_CONTAINER_ROOT_PWD` is an environment variable denoting the password
+of the `root` user in the testing container.

Taskfile.yml

@@ -13,3 +13,18 @@ tasks:
   lint-ansible:
     deps: [lint-yml]
     cmds: [LC_ALL=C.UTF-8 ansible-lint .]
+  init-tests:
+    cmds:
+      - LC_ALL=C.UTF-8 ansible-galaxy install -r requirements-test.yml --force
+  test-all:
+    deps: [init-tests]
+    dir: extensions
+    cmds:
+      - |
+        LC_ALL=C.UTF-8 \
+        LTE_CONTAINER_NAME={{ .LTE_CONTAINER_NAME }} \
+        LTE_CONTAINER_ROOT_PWD={{ .LTE_CONTAINER_ROOT_PWD }} \
+        molecule test --all
+    vars:
+      LTE_CONTAINER_NAME:
+        sh: cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 8 | head -n 1