Add integration tests for the mas module (#67442)

* Add integration tests for the mas module

See https://github.com/ansible/ansible/pull/19768.

* Implement review feedback

test/integration/targets/mas/aliases

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+needs/root
+unsupported

test/integration/targets/mas/tasks/main.yml

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+# Test code for the mas module.
+# Copyright: (c) 2020, Lukas Bestle <project-ansible@lukasbestle.com>
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+---
+# Test preparation
+- name: Uninstall Rested to ensure consistent starting point
+  mas:
+    id: 421879749
+    state: absent
+  become: yes
+
+- name: Determine whether the app is installed
+  stat:
+    path: /Applications/Rested.app
+  register: install_status
+
+- name: Ensure the app is uninstalled
+  assert:
+    that:
+    - install_status.stat.exists == false
+
+- name: Wait until the OS-internal cache was updated
+  pause:
+    seconds: 5
+
+# Installation
+- name: Check if Rested needs to be installed
+  mas:
+    id: 421879749
+    state: present
+  register: install_check
+  check_mode: yes
+
+- name: Ensure that the status would have changed
+  assert:
+    that:
+    - install_check is changed
+    - install_check.msg == "Installed 1 app(s)"
+
+- name: Determine whether the app is installed
+  stat:
+    path: /Applications/Rested.app
+  register: install_status
+
+- name: Ensure the app is not yet installed
+  assert:
+    that:
+    - install_status.stat.exists == false
+
+- name: Install Rested
+  mas:
+    id: 421879749
+    state: present
+  register: install
+
+- name: Ensure that the status changed
+  assert:
+    that:
+    - install is changed
+    - install.msg == "Installed 1 app(s)"
+
+- name: Determine whether the app is installed
+  stat:
+    path: /Applications/Rested.app
+  register: install_status
+
+- name: Ensure the app is installed
+  assert:
+    that:
+    - install_status.stat.exists == true
+
+- name: Wait until the OS-internal cache was updated
+  pause:
+    seconds: 5
+
+- name: Install Rested again
+  mas:
+    id: 421879749
+    state: present
+  register: install_again
+
+- name: Ensure that the status is unchanged (already installed)
+  assert:
+    that:
+    - install_again is not changed
+    - "'msg' not in install_again"
+
+# Uninstallation
+- name: Check if Rested needs to be uninstalled
+  mas:
+    id: 421879749
+    state: absent
+  register: uninstall_check
+  become: yes
+  check_mode: yes
+
+- name: Ensure that the status would have changed
+  assert:
+    that:
+    - uninstall_check is changed
+    - uninstall_check.msg == "Uninstalled 1 app(s)"
+
+- name: Determine whether the app is installed
+  stat:
+    path: /Applications/Rested.app
+  register: install_status
+
+- name: Ensure the app is not yet uninstalled
+  assert:
+    that:
+    - install_status.stat.exists == true
+
+- name: Unistall Rested
+  mas:
+    id: 421879749
+    state: absent
+  register: uninstall
+  become: yes
+
+- name: Ensure that the status changed
+  assert:
+    that:
+    - uninstall is changed
+    - uninstall.msg == "Uninstalled 1 app(s)"
+
+- name: Determine whether the app is installed
+  stat:
+    path: /Applications/Rested.app
+  register: uninstall_status
+
+- name: Ensure the app is uninstalled
+  assert:
+    that:
+    - uninstall_status.stat.exists == false
+
+- name: Wait until the OS-internal cache was updated
+  pause:
+    seconds: 5
+
+- name: Uninstall Rested again
+  mas:
+    id: 421879749
+    state: absent
+  register: uninstall_again
+  become: yes
+
+- name: Ensure that the status is unchanged (already uninstalled)
+  assert:
+    that:
+    - uninstall_again is not changed
+    - "'msg' not in uninstall_again"