ensure-yarn: run ensure-nodejs before

YARN needs a modern version of NodeJS and if we don't use the role
to get the latest version, we end up failing on most platforms that
ship an old version of it.

This patch also adds testing to validate that ensure-yarn alone works.

Co-Authored-By: Andreas Jaeger <aj@suse.com>
Change-Id: I83ac09bc5751c85c6f1eac550d289a300ca2255e

playbooks/javascript/pre.yaml

@@ -1,5 +1,4 @@
 - hosts: all
   roles:
-    - ensure-nodejs
     - ensure-yarn
     - ensure-javascript-packages

roles/ensure-yarn/README.rst

@@ -1 +1,6 @@
-Install yarn from yarnpkg repos
+Install yarn from yarnpkg repos.
+
+This role use the role :zuul:role:`ensure-nodejs` to ensure that
+NodeJS is installed. See the documentation for
+:zuul:role:`ensure-nodejs` and specify the version of NodeJS to
+install.

roles/ensure-yarn/tasks/main.yaml

@@ -1,3 +1,7 @@
+- name: Install NodeJS
+  include_role:
+    name: ensure-nodejs
+
 - name: Gather variables for each operating system
   include_vars: "{{ zj_item }}"
   with_first_found:

zuul-tests.d/js-roles-jobs.yaml

@@ -8,6 +8,16 @@
     vars:
       role_name: ensure-nodejs
 
+- job:
+    name: zuul-jobs-test-ensure-yarn
+    description: Test the ensure-yarn role
+    files:
+      - roles/ensure-yarn/.*
+      - roles/ensure-nodejs/.*
+      - roles/ensure-package-repositories/.*
+    run: test-playbooks/simple-role-test.yaml
+    vars:
+      role_name: ensure-yarn
 
 - job:
     name: zuul-jobs-test-fetch-javascript-tarball
@@ -37,6 +47,7 @@
     check:
       jobs: &id001
         - zuul-jobs-test-ensure-nodejs
+        - zuul-jobs-test-ensure-yarn
         - zuul-jobs-test-fetch-javascript-tarball
         - zuul-jobs-test-fetch-javascript-tarball-synchronize
     gate: