docker_swarm: hopefully fix debug CI problems, and fix check mode (#52825)

* Let's see some debug output.

* Also check LocalNodeState.

* Improve tests.

* Actually implement check mode.

* Add changelog.

* Add pretty-printing and more output.

test/integration/targets/docker_config/tasks/test_docker_config.yml

@@ -1,10 +1,14 @@
 ---
 - block:
+  - shell: "docker info --format '{% raw %}{{json .}}{% endraw %}' | python -m json.tool"
+
   - name: Make sure we're not already using Docker swarm
     docker_swarm:
       state: absent
       force: true
 
+  - shell: "docker info --format '{% raw %}{{json .}}{% endraw %}' | python -m json.tool"
+
   - name: Create a Swarm cluster
     docker_swarm:
       state: present

test/integration/targets/docker_swarm/tasks/test_swarm.yml

@@ -29,30 +29,73 @@
          - 'output.failed'
          - 'output.msg == "state is remove but all of the following are missing: node_id"'
 
+  - name: Create a Swarm cluster (check mode)
+    docker_swarm:
+      state: present
+    check_mode: yes
+    register: output_1
+
   - name: Create a Swarm cluster
     docker_swarm:
       state: present
-    register: output
+    register: output_2
+
+  - name: Create a Swarm cluster (idempotent)
+    docker_swarm:
+      state: present
+    register: output_3
+
+  - name: Create a Swarm cluster (idempotent, check mode)
+    docker_swarm:
+      state: present
+    check_mode: yes
+    register: output_4
 
   - name: assert changed when create a new swarm cluster
     assert:
       that:
-         - 'output.changed'
-         - 'output.actions[0] | regex_search("New Swarm cluster created: ")'
-         - 'output.swarm_facts.JoinTokens.Manager'
-         - 'output.swarm_facts.JoinTokens.Worker'
+         - 'output_1 is changed'
+         - 'output_2 is changed'
+         - 'output_2.actions[0] | regex_search("New Swarm cluster created: ")'
+         - 'output_2.swarm_facts.JoinTokens.Manager'
+         - 'output_2.swarm_facts.JoinTokens.Worker'
+         - 'output_3 is not changed'
+         - 'output_4 is not changed'
+
+  - name: Remove a Swarm cluster (check mode)
+    docker_swarm:
+      state: absent
+      force: true
+    check_mode: yes
+    register: output_1
 
   - name: Remove a Swarm cluster
     docker_swarm:
       state: absent
       force: true
-    register: output
+    register: output_2
+
+  - name: Remove a Swarm cluster (idempotent)
+    docker_swarm:
+      state: absent
+      force: true
+    register: output_3
+
+  - name: Remove a Swarm cluster (idempotent, check mode)
+    docker_swarm:
+      state: absent
+      force: true
+    check_mode: yes
+    register: output_4
 
   - name: assert changed when remove a swarm cluster
     assert:
       that:
-         - 'output.changed'
-         - 'output.actions[0] == "Node has left the swarm cluster"'
+         - 'output_1 is changed'
+         - 'output_2 is changed'
+         - 'output_2.actions[0] == "Node has left the swarm cluster"'
+         - 'output_3 is not changed'
+         - 'output_4 is not changed'
 
   always:
   - name: Cleanup