About In-memory Template Loader

When testing template functionality, you might want to use the locmem template loader with template content defined directly in the tests. Here's an example:

from django.template.loader import render_to_string
from django.test import SimpleTestCase, override_settings

# Use override_settings to inject a in-memory template loader
@override_settings(
    TEMPLATES=[{
        "BACKEND": "django.template.backends.django.DjangoTemplates",
        "DIRS": [],
        "OPTIONS": {
            "loaders": [
                # locmem loader: maps template names to strings in memory
                (
                    "django.template.loaders.locmem.Loader",
                    {
                        "welcome.html": (
                            "{% load greeting_tags %}"
                            "<h1>{% greet full_name %}</h1>"
                        ),
                    },
                ),
            ],
            "builtins": [],
        },
    }]
)
class GreetTagTest(SimpleTestCase):
    def test_greet_tag_renders(self):
        result = render_to_string(
            "welcome.html",
            {"full_name": "World"}
        )
        self.assertEqual(result, "<h1>Hello, World!</h1>")