Build from source idempotence. Closes #7

.travis.yml

@@ -10,3 +10,10 @@ script:
   - echo localhost > inventory
   - ansible-playbook --syntax-check -i inventory test.yml
   - ansible-playbook -i inventory test.yml --connection=local --sudo
+  # Taken from https://servercheck.in/blog/testing-ansible-roles-travis-ci-github
+  # Run the role/playbook again, checking to make sure it's idempotent.
+  - >
+    ansible-playbook -i inventory test.yml --connection=local --sudo
+    | grep -q 'changed=0.*failed=0'
+    && (echo 'Idempotence test: pass' && exit 0)
+    || (echo 'Idempotence test: fail' && exit 1)

tasks/main.yml

@@ -2,5 +2,13 @@
 
 - include: package.yml
   when: nodejs_install_method == "package"
-- include: source.yml
+
+- name: node.js | Check if the node version is already installed
+  command: node --version
+  ignore_errors: yes
+  register: node_version
+  changed_when: node_version.rc != 0 or node_version.stdout != "v{{ nodejs_version }}"
   when: nodejs_install_method == "source"
+
+- include: source.yml
+  when: nodejs_install_method == "source" and node_version.changed