test: test to illustrate bug in component caching when using include tag (#1135)

* test: test to illustrate bug in component caching when using include tag

* fix: add cleanup for render context in component rendering

* refactor: clarify cleanup comment in component rendering logic

* refactor: fix linter errors

* test: formatting and unnecessary test setup

---------

Co-authored-by: Juro Oravec <juraj.oravec.josefson@gmail.com>

src/django_components/component.py

@@ -1306,6 +1306,8 @@ class Component(
         # The component rendering was short-circuited by an extension, skipping
         # the rest of the rendering process. This may be for example a cached content.
         if result_override is not None:
+            # Cleanup needs to be done even if short-circuited
+            context.render_context.pop()
             return result_override
 
         # We pass down the components the info about the component's parent.

tests/templates/test_cached_component_inside_include_base.html

@@ -0,0 +1,4 @@
+{% include "test_cached_component_inside_include_sub.html" %}
+{% block content %}
+    THIS_IS_IN_BASE_TEMPLATE_SO_SHOULD_BE_OVERRIDDEN
+{% endblock %}

tests/templates/test_cached_component_inside_include_sub.html

@@ -0,0 +1 @@
+{% component "test_component" / %}

tests/test_component_cache.py

@@ -2,8 +2,10 @@ import time
 from typing import Any
 
 from django.core.cache import caches
+from django.template import Template
+from django.template.context import Context
 
-from django_components import Component
+from django_components import Component, register
 from django_components.testing import djc_test
 
 from .testutils import setup_test_config
@@ -207,3 +209,27 @@ class TestComponentCache:
         # The key should use the custom hash methods
         expected_key = "components:cache:TestComponent_28880f:custom-args-and-kwargs"
         assert component.cache.get_cache_key(1, 2, key="value") == expected_key
+
+    def test_cached_component_inside_include(self):
+
+        @register("test_component")
+        class TestComponent(Component):
+            template = "Hello"
+
+            class Cache:
+                enabled = True
+
+        template = Template("""
+            {% extends "test_cached_component_inside_include_base.html" %}
+            {% block content %}
+                THIS_IS_IN_ACTUAL_TEMPLATE_SO_SHOULD_NOT_BE_OVERRIDDEN
+            {% endblock %}
+        """)
+
+        result = template.render(Context({}))
+        assert "THIS_IS_IN_BASE_TEMPLATE_SO_SHOULD_BE_OVERRIDDEN" not in result
+        assert "THIS_IS_IN_ACTUAL_TEMPLATE_SO_SHOULD_NOT_BE_OVERRIDDEN" in result
+
+        result_cached = template.render(Context({}))
+        assert "THIS_IS_IN_BASE_TEMPLATE_SO_SHOULD_BE_OVERRIDDEN" not in result_cached
+        assert "THIS_IS_IN_ACTUAL_TEMPLATE_SO_SHOULD_NOT_BE_OVERRIDDEN" in result_cached