Add an ensure-tox test job

Change-Id: I1116e745dd7f9e81af268922f046c9e8073b8447

test-playbooks/ensure-tox.yaml

@@ -0,0 +1,63 @@
+- hosts: all
+  name: Test ensure-tox when tox is installed in system default
+  tasks:
+    - name: Verify tox is pre-installed on OpenDev images
+      command: "tox --version"
+    - name: Run ensure-tox with tox already installed
+      include_role:
+        name: ensure-tox
+    - name: Verify tox_executable is not set by ensure-tox
+      assert:
+        that:
+          - tox_executable is not defined
+
+- hosts: all
+  name: Test ensure-tox when tox_executable is already set and tox is installed
+  tasks:
+    - name: Run ensure-tox with tox not installed
+      include_role:
+        name: ensure-tox
+      vars:
+        tox_executable: "python3 -m tox"
+    - name: Verify tox_executable is not set by ensure-tox
+      assert:
+        that:
+          - tox_executable is not defined
+
+- hosts: all
+  name: Remove pre-installed tox
+  tasks:
+    - name: Remove tox package with pip
+      shell: pip uninstall -y tox
+      become: true
+      ignore_errors: true
+    - name: Remove tox package with pip3
+      shell: pip3 uninstall -y tox
+      become: true
+      ignore_errors: true
+    - name: Verify tox is not installed
+      command: "tox --version"
+      register: result
+      failed_when: result.rc == 0
+
+- hosts: all
+  name: Test ensure-tox when tox is not installed
+  tasks:
+    - name: Remove tox package
+      shell: pip uninstall tox || pip3 uninstall tox
+      become: true
+    - name: Verify tox is not installed
+      command: "tox --version"
+      register: result
+      failed_when: result.rc == 0
+    - name: Run ensure-tox with tox not installed
+      include_role:
+        name: ensure-tox
+    - name: Verify tox_executable is set
+      assert:
+        that:
+          - tox_executable == "{{ ansible_user_dir }}/.local/bin/tox"
+    - name: Verify tox is installed
+      command: "{{ tox_executable }} --version"
+      register: result
+      failed_when: result.rc != 0

zuul-tests.d/python-jobs.yaml

@@ -7,6 +7,13 @@
     vars:
       role_name: ensure-sphinx
 
+- job:
+    name: zuul-jobs-test-ensure-tox
+    description: Test the ensure-tox role
+    files:
+      - roles/ensure-tox/.*
+    run: test-playbooks/ensure-tox.yaml
+
 - job:
     name: zuul-jobs-test-tox-siblings
     description: Test the tox role's sibling functionality
@@ -46,6 +53,7 @@
     check:
       jobs: &id001
         - zuul-jobs-test-ensure-sphinx
+        - zuul-jobs-test-ensure-tox
         - zuul-jobs-test-tox-siblings
         - zuul-jobs-test-fetch-tox-output
         - zuul-jobs-test-fetch-tox-output-synchronize