refactor: Fix template caching, expose cached_template, Component.template API changes (#647)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

tests/test_template.py

@@ -0,0 +1,67 @@
+from django.template import Context, Template
+from django.test import override_settings
+
+from django_components import Component, cached_template, types
+
+from .django_test_setup import setup_test_config
+from .testutils import BaseTestCase
+
+setup_test_config({"autodiscover": False})
+
+
+class TemplateCacheTest(BaseTestCase):
+    def test_cached_template(self):
+        template_1 = cached_template("Variable: <strong>{{ variable }}</strong>")
+        template_1._test_id = "123"
+
+        template_2 = cached_template("Variable: <strong>{{ variable }}</strong>")
+
+        self.assertEqual(template_2._test_id, "123")
+
+    def test_cached_template_accepts_class(self):
+        class MyTemplate(Template):
+            pass
+
+        template = cached_template("Variable: <strong>{{ variable }}</strong>", MyTemplate)
+        self.assertIsInstance(template, MyTemplate)
+
+    @override_settings(COMPONENTS={"template_cache_size": 2})
+    def test_cache_discards_old_entries(self):
+        template_1 = cached_template("Variable: <strong>{{ variable }}</strong>")
+        template_1._test_id = "123"
+
+        template_2 = cached_template("Variable2")
+        template_2._test_id = "456"
+
+        # Templates 1 and 2 should still be available
+        template_1_copy = cached_template("Variable: <strong>{{ variable }}</strong>")
+        self.assertEqual(template_1_copy._test_id, "123")
+
+        template_2_copy = cached_template("Variable2")
+        self.assertEqual(template_2_copy._test_id, "456")
+
+        # But once we add the third template, template 1 should go
+        cached_template("Variable3")
+
+        template_1_copy2 = cached_template("Variable: <strong>{{ variable }}</strong>")
+        self.assertEqual(hasattr(template_1_copy2, "_test_id"), False)
+
+    def test_component_template_is_cached(self):
+        class SimpleComponent(Component):
+            def get_template(self, context):
+                content: types.django_html = """
+                    Variable: <strong>{{ variable }}</strong>
+                """
+                return content
+
+            def get_context_data(self, variable=None):
+                return {
+                    "variable": variable,
+                }
+
+        comp = SimpleComponent()
+        template_1 = comp._get_template(Context({}))
+        template_1._test_id = "123"
+
+        template_2 = comp._get_template(Context({}))
+        self.assertEqual(template_2._test_id, "123")