a_module test: fix crash in case of tombstoning (#3660)

* Fix crash in case of tombstoning.

* Extend tests.

changelogs/fragments/3660-a_module-tombstone.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - "a_module test plugin - fix crash when testing a module name that was tombstoned (https://github.com/ansible-collections/community.general/pull/3660)."

plugins/test/a_module.py

@@ -7,6 +7,11 @@ __metaclass__ = type
 
 from ansible.plugins.loader import action_loader, module_loader
 
+try:
+    from ansible.errors import AnsiblePluginRemovedError
+except ImportError:
+    AnsiblePluginRemovedError = Exception
+
 
 def a_module(term):
     """
@@ -14,6 +19,7 @@ def a_module(term):
       - 'community.general.ufw' is community.general.a_module
       - 'community.general.does_not_exist' is not community.general.a_module
     """
+    try:
         for loader in (action_loader, module_loader):
             data = loader.find_plugin(term)
             # Ansible 2.9 returns a tuple
@@ -22,6 +28,8 @@ def a_module(term):
             if data is not None:
                 return True
         return False
+    except AnsiblePluginRemovedError:
+        return False
 
 
 class TestModule(object):

tests/integration/targets/test_a_module/runme.yml

@@ -23,3 +23,15 @@
           # Local collection module (that exist or not)
           - "'testns.testcoll.collection_module' is community.general.a_module"
           - "'testns.testcoll.foobar' is not community.general.a_module"
+
+    - name: Test a_module in case of routing
+      assert:
+        that:
+          # Redirected module
+          - "'ufw' is community.general.a_module"
+          # Redirected module where target collection does not exist
+          # (the target collection must not have been installed in CI!)
+          - "'onyx_pfc_interface' is not community.general.a_module"
+          # Tombstoned module
+          - "'community.general.docker_image_facts' is not community.general.a_module"
+      when: ansible_version.string is version('2.10.0', '>=')