Add 'state' parameter for alternatives (#4557) (#4576)

* Add 'activate' parameter for alternatives

Allow alternatives to be installed without being set as the current
selection.

* add changelog fragment

* Apply suggestions from code review

Co-authored-by: Felix Fontein <felix@fontein.de>

* rename 'activate' -> 'selected'

* rework 'selected' parameter -> 'state'

* handle unsetting of currently selected alternative

* add integration tests for 'state' parameter

* fix linting issues

* fix for Python 2.7 compatibility

* Remove alternatives file.

Co-authored-by: Felix Fontein <felix@fontein.de>
(cherry picked from commit 29c49febd9)

Co-authored-by: Tanner Prestegard <tprestegard@users.noreply.github.com>

tests/integration/targets/alternatives/tasks/main.yml

@@ -49,6 +49,12 @@
   # Test that path is checked: alternatives must fail when path is nonexistent
   - import_tasks: path_is_checked.yml
 
+  # Test operation of the 'state' parameter
+  - block:
+    - include_tasks: remove_links.yml
+    - include_tasks: tests_state.yml
+
+  # Cleanup
   always:
     - include_tasks: remove_links.yml
 
@@ -62,6 +68,7 @@
         path: '/usr/bin/dummy{{ item }}'
         state: absent
       with_sequence: start=1 end=4
+
   # *Disable tests on Fedora 24*
   # Shippable Fedora 24 image provides chkconfig-1.7-2.fc24.x86_64 but not the
   # latest available version (chkconfig-1.8-1.fc24.x86_64). update-alternatives

tests/integration/targets/alternatives/tasks/remove_links.yml

@@ -3,5 +3,6 @@
     path: '{{ item }}'
     state: absent
   with_items:
+    - "{{ alternatives_dir }}/dummy"
     - /etc/alternatives/dummy
     - /usr/bin/dummy

tests/integration/targets/alternatives/tasks/tests_state.yml

@@ -0,0 +1,71 @@
+# Add a few dummy alternatives with state = present and make sure that the
+# group is in 'auto' mode and the highest priority alternative is selected.
+- name: Add some dummy alternatives with state = present
+  alternatives:
+    name: dummy
+    path: "/usr/bin/dummy{{ item.n }}"
+    link: /usr/bin/dummy
+    priority: "{{ item.priority }}"
+    state: present
+  loop:
+    - { n: 1, priority: 50 }
+    - { n: 2, priority: 70 }
+    - { n: 3, priority: 25 }
+
+- name: Ensure that the link group is in auto mode
+  shell: 'head -n1 {{ alternatives_dir }}/dummy | grep "^auto$"'
+
+# Execute current selected 'dummy' and ensure it's the alternative we expect
+- name: Execute the current dummy command
+  shell: dummy
+  register: cmd
+
+- name: Ensure that the expected command was executed
+  assert:
+    that:
+      - cmd.stdout == "dummy2"
+
+# Add another alternative with state = 'selected' and make sure that
+# this change results in the group being set to manual mode, and the
+# new alternative being the selected one.
+- name: Add another dummy alternative with state = selected
+  alternatives:
+    name: dummy
+    path: /usr/bin/dummy4
+    link: /usr/bin/dummy
+    priority: 10
+    state: selected
+
+- name: Ensure that the link group is in manual mode
+  shell: 'head -n1 {{ alternatives_dir }}/dummy | grep "^manual$"'
+
+- name: Execute the current dummy command
+  shell: dummy
+  register: cmd
+
+- name: Ensure that the expected command was executed
+  assert:
+    that:
+      - cmd.stdout == "dummy4"
+
+# Set the currently selected alternative to state = 'present' (was previously
+# selected), and ensure that this results in the group being set to 'auto'
+# mode, and the highest priority alternative is selected.
+- name: Set current selected dummy to state = present
+  alternatives:
+    name: dummy
+    path: /usr/bin/dummy4
+    link: /usr/bin/dummy
+    state: present
+
+- name: Ensure that the link group is in auto mode
+  shell: 'head -n1 {{ alternatives_dir }}/dummy | grep "^auto$"'
+
+- name: Execute the current dummy command
+  shell: dummy
+  register: cmd
+
+- name: Ensure that the expected command was executed
+  assert:
+    that:
+      - cmd.stdout == "dummy2"