feat: Add support for multi-level inherited templates

This solves the issue where a grandchild template
wants to render a block that does not exist in itself
or the parent template, but exists in the grandparent.

.gitignore

@@ -29,3 +29,6 @@ pip-log.txt
 
 # Editor files
 .idea
+
+# Virtual environment
+.venv

render_block/django.py

@@ -33,24 +33,33 @@ def django_render_block(template, block_name, context, request=None):
 
     # Bind the template to the context.
     with context_instance.bind_template(template):
-        # Before trying to render the template, we need to traverse the tree of
-        # parent templates and find all blocks in them.
-        parent_template = _build_block_context(template, context_instance)
+        parent_templates = []
+
+        # Populates parent_templates with the parent templates of the current
+        # template, and adds the blocks from those parent templates to the
+        # context.
+        _build_block_context(template, context_instance)
 
         try:
             return _render_template_block(template, block_name, context_instance)
         except BlockNotFound:
             # The block wasn't found in the current template.
 
             # If there's no parent template (i.e. no ExtendsNode), re-raise.
-            if not parent_template:
+            if not len(parent_templates):
                 raise
 
             # Check the parent template for this block.
-            return _render_template_block(parent_template, block_name, context_instance)
+            for parent_template in parent_templates:
+                try:
+                    return _render_template_block(
+                        parent_template, block_name, context_instance
+                    )
+                except BlockNotFound:
+                    continue
 
 
-def _build_block_context(template, context):
+def _build_block_context(template, context, parent_templates):
     """Populate the block context with BlockNodes from parent templates."""
 
     # Ensure there's a BlockContext before rendering. This allows blocks in
@@ -74,9 +83,9 @@ def _build_block_context(template, context):
                 }
             )
 
-            _build_block_context(compiled_parent, context)
-            return compiled_parent
-
+            _build_block_context(compiled_parent, context, parent_templates)
+            parent_templates.insert(0, compiled_parent)
+            return parent_templates
         # The ExtendsNode has to be the first non-text node.
         if not isinstance(node, TextNode):
             break

tests/templates/test7_django.html

@@ -0,0 +1 @@
+{% block block1 %}block1 from test7{% endblock %}

tests/templates/test8_django.html

@@ -0,0 +1 @@
+{% extends 'test7_django.html' %}

tests/templates/test9_django.html

@@ -0,0 +1 @@
+{% extends "test8_django.html" %}

tests/tests.py

@@ -91,6 +91,10 @@ def test_subblock_no_parent(self):
         result = render_block_to_string("test_sub.html", "first")
         self.assertEqual(result, "\nbar\n")
 
+    def test_multi_level_inherited_template_block(self):
+        result = render_block_to_string("test9_django.html", "block1")
+        self.assertEqual(result, "block1 from test7")
+
     def test_context(self):
         """Test that a context is properly rendered in a template."""
         data = "block2 from test5"