virt_net: idempotency of create/stop actions (#53276)

Currently, if we try to stop or start a network two time in a row, the
second call will fail. With this patch:

- we don't recreate a network, if it exists
- we only stop a network if it's active, and so we avoid an exception
  saying the network is not active

* test: mock libvirt

* add integration tests for virt_net

* test: enable virt_net test on RedHat 7 and 8

* ci: use the unsupported alias

* tests that require privileged mode are run in VM

* virt_net/create raise unexpected libvirt exception

* import mock from units.compat

* virt_net: do not call create() on "active" network

* virt_net func test: only clean up the libvirt packages

* test: virt_net: don't use assert_called()

* virt_net: add the destructive alias

* move the test in virt_net dir

* test/virt_net: clean up the network at the end

test/integration/targets/virt_net/aliases

@@ -0,0 +1,5 @@
+shippable/posix/group1
+skip/freebsd
+skip/osx
+needs/privileged
+destructive

test/integration/targets/virt_net/files/foobar.xml

@@ -0,0 +1,9 @@
+<network>
+    <name>foobar</name>
+    <forward mode='nat'/>
+    <ip address='192.168.125.1' netmask='255.255.255.0'>
+        <dhcp>
+            <range start='192.168.125.2' end='192.168.125.254'/>
+        </dhcp>
+    </ip>
+</network>

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

@@ -0,0 +1,78 @@
+---
+- include_vars: '{{ item }}'
+  with_first_found:
+    - "{{ ansible_distribution }}-{{ ansible_distribution_version}}.yml"
+    - "{{ ansible_distribution }}-{{ ansible_distribution_major_version}}.yml"
+    - "{{ ansible_distribution }}.yml"
+    - "default.yml"
+
+- block:
+    - name: Install libvirt packages
+      package:
+        name: "{{ virt_net_packages }}"
+
+    - name: Start libvirt
+      service:
+        name: libvirtd
+        state: started
+
+    - name: Define the foobar network
+      virt_net:
+        command: define
+        name: foobar
+        xml: '{{ lookup("file", "foobar.xml") }}'
+    
+    - name: Define the foobar network (again)
+      virt_net:
+        command: define
+        name: foobar
+        xml: '{{ lookup("file", "foobar.xml") }}'
+      register: second_virt_net_define
+    
+    - name: Start the default network
+      virt_net:
+        uri: qemu:///system
+        command: start
+        name: foobar
+    
+    - name: Start the default network (again)
+      virt_net:
+        uri: qemu:///system
+        command: start
+        name: foobar
+      register: second_virt_net_start
+
+    - name: Destroy the foobar network
+      virt_net:
+        command: destroy
+        name: foobar
+
+    - name: Undefine the foobar network
+      virt_net:
+        command: undefine
+        name: foobar
+      register: second_virt_net_define
+
+    - name: Undefine the foobar network (again)
+      virt_net:
+        command: undefine
+        name: foobar
+      register: second_virt_net_undefine
+
+    - name: Ensure the second calls return "unchanged"
+      assert:
+        that:
+          - "second_virt_net_start is not changed"
+          - "second_virt_net_define is not changed"
+          - "second_virt_net_undefine is not changed"
+    
+  always:
+    - name: Stop libvirt
+      service:
+        name: libvirtd
+        state: stopped
+
+    - name: Remove only the libvirt packages
+      package:
+        name: "{{ virt_net_packages|select('match', '.*libvirt.*')|list }}"
+        state: absent

test/integration/targets/virt_net/vars/Debian.yml

@@ -0,0 +1,6 @@
+---
+virt_net_packages:
+  - libvirt-daemon
+  - libvirt-daemon-system
+  - python-libvirt
+  - python-lxml

test/integration/targets/virt_net/vars/Fedora-29.yml

@@ -0,0 +1,6 @@
+---
+virt_net_packages:
+  - libvirt
+  - libvirt-daemon
+  - python3-libvirt
+  - python3-lxml

test/integration/targets/virt_net/vars/RedHat-7.yml

@@ -0,0 +1,6 @@
+---
+virt_net_packages:
+  - libvirt
+  - libvirt-daemon
+  - libvirt-python
+  - python-lxml

test/integration/targets/virt_net/vars/RedHat-8.yml

@@ -0,0 +1,6 @@
+---
+virt_net_packages:
+  - libvirt
+  - libvirt-daemon
+  - python3-libvirt
+  - python3-lxml

test/integration/targets/virt_net/vars/Ubuntu-16.04.yml

@@ -0,0 +1,5 @@
+---
+virt_net_packages:
+  - libvirt-daemon
+  - python-libvirt
+  - python-lxml

test/integration/targets/virt_net/vars/Ubuntu-18.04.yml

@@ -0,0 +1,5 @@
+---
+virt_net_packages:
+  - libvirt-daemon
+  - python-libvirt
+  - python-lxml

test/integration/targets/virt_net/vars/Ubuntu-18.10.yml

@@ -0,0 +1,6 @@
+---
+virt_net_packages:
+  - libvirt-daemon
+  - libvirt-daemon-system
+  - python-libvirt
+  - python-lxml

test/integration/targets/virt_net/vars/default.yml

@@ -0,0 +1,5 @@
+---
+virt_net_packages:
+  - libvirt-daemon
+  - python-libvirt
+  - python-lxml