Add role to ensure tox is installed on target host

Change-Id: I8d2ee07bc84efb7eb0eb23a64ecdff97fd5cecb6

roles/tobiko-ensure-tox/defaults/main.yaml

@@ -0,0 +1,4 @@
+---
+
+tox_executable: tox
+tox_min_version: 3.4

roles/tobiko-ensure-tox/meta/main.yaml

@@ -0,0 +1,5 @@
+---
+
+dependencies:
+  - role: tobiko-common
+  - role: tobiko-ensure-python

roles/tobiko-ensure-tox/tasks/main.yaml

@@ -0,0 +1,23 @@
+---
+
+- name: "ensure Tox is installed"
+  command: |
+    '{{ python_executable }}' -m pip install --user 'tox>={{ tox_min_version }}'
+  register: result
+  changed_when: "'Successfully installed' in result.stdout"
+
+
+- name: "set tox_executable fact"
+  set_fact:
+    tox_executable: "{{ ansible_user_dir }}/.local/bin/tox"
+    cacheable: true
+  when: result is changed
+
+
+- name: "get installed Tox version"
+  command: "{{ tox_executable }} --version"
+  register: get_installed_tox_version
+
+
+- name: "show Tox installed version"
+  debug: var=get_installed_tox_version.stdout_lines

roles/tobiko-tox/defaults/main.yaml

@@ -2,7 +2,7 @@
 
 # Directory where test cases has been deployed to
 tox_dir: '{{ test_dir | realpath }}'
-tox_command: tox
+tox_command: '{{ tox_executable | default(tox) }}'
 tox_environment: {}
 tox_envlist:
 tox_extra_args: ''

roles/tobiko-tox/meta/main.yaml

@@ -3,3 +3,4 @@
 dependencies:
   - role: tobiko-common
   - role: tobiko-ensure-python
+  - role: tobiko-ensure-tox