Do not crash templating when filter/test name is not a valid Ansible plugin name (#78913)

* Do not crash templating when filter/test name is not a valid Ansible plugin name.
* Store and re-raise KeyError if there was one.

Co-authored-by: s-hertel <19572925+s-hertel@users.noreply.github.com>

changelogs/fragments/78913-template-missing-filter-test.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - "Do not crash when templating an expression with a test or filter that is not a valid Ansible filter name (https://github.com/ansible/ansible/issues/78912, https://github.com/ansible/ansible/pull/78913)."

lib/ansible/template/__init__.py

@@ -423,12 +423,13 @@ class JinjaPluginIntercept(MutableMapping):
         if not isinstance(key, string_types):
             raise ValueError('key must be a string, got %s instead' % type(key))
 
+        original_exc = None
         if key not in self._loaded_builtins:
             plugin = None
             try:
                 plugin = self._pluginloader.get(key)
             except (AnsibleError, KeyError) as e:
-                raise TemplateSyntaxError('Could not load "%s": %s' % (key, to_native(e)), 0)
+                original_exc = e
             except Exception as e:
                 display.vvvv('Unexpected plugin load (%s) exception: %s' % (key, to_native(e)))
                 raise e
@@ -439,8 +440,11 @@ class JinjaPluginIntercept(MutableMapping):
                 self._delegatee[key] = plugin.j2_function
                 self._loaded_builtins.add(key)
 
-        # let it trigger keyerror if we could not find ours or jinja2 one
+        # raise template syntax error if we could not find ours or jinja2 one
-        func = self._delegatee[key]
+        try:
+            func = self._delegatee[key]
+        except KeyError as e:
+            raise TemplateSyntaxError('Could not load "%s": %s' % (key, to_native(original_exc or e)), 0)
 
         # if i do have func and it is a filter, it nees wrapping
         if self._pluginloader.type == 'filter':

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

@@ -16,3 +16,20 @@
   vars:
     # Kind of hack to just send a JSON string through jinja, by templating out nothing
     foo: '{{ "" }}{"null": null, "true": true, "false": false}'
+
+- name: Make sure that test with name that isn't a valid Ansible plugin name does not result in a crash (1/2)
+  set_fact:
+    foo: '{{ [{"failed": false}] | selectattr("failed", "==", true) }}'
+
+- name: Make sure that test with name that isn't a valid Ansible plugin name does not result in a crash (2/2)
+  template:
+    src: invalid_test_name.j2
+    dest: /tmp/foo
+  ignore_errors: true
+  register: result
+
+- assert:
+    that:
+      - result is failed
+      - >-
+        "TemplateSyntaxError: Could not load \"asdf \": 'invalid plugin name: ansible.builtin.asdf '" in result.msg

test/integration/targets/templating/templates/invalid_test_name.j2

@@ -0,0 +1 @@
+{{ [{"failed": false}] | selectattr("failed", "asdf ", true) }}