Add a generic process-test-results role

Takes an stestr or testr repo as input and generates a subunit
file and an html report out of it. The files are stored in the
staging area on the test node.

This in combination with a generic role to pull the staging
folder to the zuul executor is meant to eventually replace to
existing roles:
- fetch-testr-output
- fetch-stestr-output

Change-Id: Id6149d4e265ab9f0ab6d8faeffdec651c63dc056

roles/process-test-results/README.rst

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+Process test results
+
+Take a testr / stestr repo as input. Produce subunit from the latest
+run and the html report using subunit2html.
+
+**Role Variables**
+
+.. zuul:rolevar:: test_results_dir
+   :default: None
+
+   The folder where the [s]testr repo lives.
+
+.. zuul:rolevar:: tox_envdir
+   :default: venv
+
+   The name of the virtual environemnt created by tox to run tests.
+   This may be different from the name of the tox environment.
+
+.. zuul:rolevar:: stage_dir
+   :default: {{ ansible_user_dir }}
+
+   Folder into which the output files will be written. Assumption is that
+   the user that runs this role has read access to test results and write
+   access to tempest_work_dir.
+
+.. zuul:rolevar:: subunit2html
+   :default: /usr/os-testr-env/bin/subunit2html
+
+   The full path to subunit2html. This utility is part of os-testr,
+   and it's usually baked into test images, hence the default value.
+
+.. zuul:rolevar:: test_results_stage_name
+   :default: test_results
+
+   The name of the subunit and html files generated.

roles/process-test-results/defaults/main.yaml

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+tox_envdir: venv
+stage_dir: "{{ ansible_user_dir }}"
+subunit2html: /usr/os-testr-env/bin/subunit2html
+test_results_stage_name: test_results

roles/process-test-results/tasks/main.yaml

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+# NOTE(andreaf) There could be more than one repo in the test folder.
+# Since that's unlikely we don't provide a variable to select the
+# test runner and we pick the first hit.
+- name: Discover stestr repo
+  stat:
+    path: "{{ test_results_dir }}/.stestr"
+  register: stestr_repo
+
+- name: Discover testr repo
+  stat:
+    path: "{{ test_results_dir }}/.testrepository"
+  register: testr_repo
+  when: not stestr_repo.stat.exists
+
+- name: Use stestr test runner
+  set_fact:
+    test_runner: ".tox/{{ tox_envdir }}/bin/stestr"
+  when: stestr_repo.stat.exists
+
+- name: Use legacy testr test runner
+  set_fact:
+    test_runner: ".tox/{{ tox_envdir }}/bin/testr"
+  when: not stestr_repo.stat.exists and testr_repo.stat.exists
+
+- name: Check if the venv has been created
+  stat:
+    path: "{{ test_results_dir }}/.tox/{{ tox_envdir }}"
+  register: run_venv
+
+- name: Make sure test results are world readable
+  file:
+    path: "{{ test_results_dir }}"
+    mode: "a+rX"
+    recurse: true
+  become: true
+
+- name: Create a subunit file from the last run
+  shell: "{{ test_runner }} last --subunit > {{ stage_dir }}/{{ test_results_stage_name }}.subunit"
+  args:
+    chdir: "{{ test_results_dir }}"
+  when: run_venv.stat.exists and test_runner is defined
+  register: subunit_report
+
+- name: Generate the html report for the last run
+  command: "{{ subunit2html }} ./{{ test_results_stage_name}}.subunit {{ test_results_stage_name }}.html"
+  args:
+    chdir: "{{ stage_dir }}"
+  when: run_venv.stat.exists and test_runner is defined
+  register: html_report