text: from django.template import TemplateDoesNotExist
  from django.template.loader import get_template, render_to_string, select_template
  from django.test import SimpleTestCase, override_settings
  from django.test.client import RequestFactory
  
  
  @override_settings(
      TEMPLATES=[
          {
              "BACKEND": "django.template.backends.dummy.TemplateStrings",
              "APP_DIRS": True,
          },
          {
              "BACKEND": "django.template.backends.django.DjangoTemplates",
              "OPTIONS": {
                  "context_processors": [
                      "django.template.context_processors.request",
                  ],
                  "loaders": [
                      "django.template.loaders.filesystem.Loader",
                      "django.template.loaders.app_directories.Loader",
                  ],
              },
          },
      ]
  )
  class TemplateLoaderTests(SimpleTestCase):
      def test_get_template_first_engine(self):
          template = get_template("template_loader/hello.html")
          self.assertEqual(template.render(), "Hello! (template strings)\n")
  
      def test_get_template_second_engine(self):
          template = get_template("template_loader/goodbye.html")
          self.assertEqual(template.render(), "Goodbye! (Django templates)\n")
  
      def test_get_template_using_engine(self):
          template = get_template("template_loader/hello.html", using="django")
          self.assertEqual(template.render(), "Hello! (Django templates)\n")
  
      def test_get_template_not_found(self):
          with self.assertRaises(TemplateDoesNotExist) as e:
              get_template("template_loader/unknown.html")
          self.assertEqual(
              e.exception.chain[-1].tried[0][0].template_name,
              "template_loader/unknown.html",
          )
          self.assertEqual(e.exception.chain[-1].backend.name, "django")
  
      def test_select_template_first_engine(self):
          template = select_template(
              ["template_loader/unknown.html", "template_loader/hello.html"]
          )
          self.assertEqual(template.render(), "Hello! (template strings)\n")
  
      def test_select_template_second_engine(self):
          template = select_template(
              ["template_loader/unknown.html", "template_loader/goodbye.html"]
          )
          self.assertEqual(template.render(), "Goodbye! (Django templates)\n")
  
      def test_select_template_using_engine(self):
          template = select_template(
              ["template_loader/unknown.html", "template_loader/hello.html"],
              using="django",
          )
          self.assertEqual(template.render(), "Hello! (Django templates)\n")
  
      def test_select_template_empty(self):
          with self.assertRaises(TemplateDoesNotExist):
              select_template([])
  
      def test_select_template_string(self):
          with self.assertRaisesMessage(
              TypeError,
              "select_template() takes an iterable of template names but got a "
              "string: 'template_loader/hello.html'. Use get_template() if you "
              "want to load a single template by name.",
          ):
              select_template("template_loader/hello.html")
  
      def test_select_template_not_found(self):
          with self.assertRaises(TemplateDoesNotExist) as e:
              select_template(
                  ["template_loader/unknown.html", "template_loader/missing.html"]
              )
          self.assertEqual(
              e.exception.chain[0].tried[0][0].template_name,
              "template_loader/unknown.html",
          )
          self.assertEqual(e.exception.chain[0].backend.name, "dummy")
          self.assertEqual(
              e.exception.chain[-1].tried[0][0].template_name,
              "template_loader/missing.html",
          )
          self.assertEqual(e.exception.chain[-1].backend.name, "django")
  
      def test_select_template_tries_all_engines_before_names(self):
          template = select_template(
              ["template_loader/goodbye.html", "template_loader/hello.html"]
          )
          self.assertEqual(template.render(), "Goodbye! (Django templates)\n")
  
      def test_render_to_string_first_engine(self):
          content = render_to_string("template_loader/hello.html")
          self.assertEqual(content, "Hello! (template strings)\n")
  
      def test_render_to_string_second_engine(self):
          content = render_to_string("template_loader/goodbye.html")
          self.assertEqual(content, "Goodbye! (Django templates)\n")
  
      def test_render_to_string_with_request(self):
          request = RequestFactory().get("/foobar/")
          content = render_to_string("template_loader/request.html", request=request)
          self.assertEqual(content, "/foobar/\n")
  
      def test_render_to_string_using_engine(self):
          content = render_to_string("template_loader/hello.html", using="django")
          self.assertEqual(content, "Hello! (Django templates)\n")
  
      def test_render_to_string_not_found(self):
          with self.assertRaises(TemplateDoesNotExist) as e:
              render_to_string("template_loader/unknown.html")
          self.assertEqual(
              e.exception.chain[-1].tried[0][0].template_name,
              "template_loader/unknown.html",
          )
          self.assertEqual(e.exception.chain[-1].backend.name, "django")
  
      def test_render_to_string_with_list_first_engine(self):
          content = render_to_string(
              ["template_loader/unknown.html", "template_loader/hello.html"]
          )
          self.assertEqual(content, "Hello! (template strings)\n")
  
      def test_render_to_string_with_list_second_engine(self):
          content = render_to_string(
              ["template_loader/unknown.html", "template_loader/goodbye.html"]
          )
          self.assertEqual(content, "Goodbye! (Django templates)\n")
  
      def test_render_to_string_with_list_using_engine(self):
          content = render_to_string(
              ["template_loader/unknown.html", "template_loader/hello.html"],
              using="django",
          )
          self.assertEqual(content, "Hello! (Django templates)\n")
  
      def test_render_to_string_with_list_empty(self):
          with self.assertRaises(TemplateDoesNotExist):
              render_to_string([])
  
      def test_render_to_string_with_list_not_found(self):
          with self.assertRaises(TemplateDoesNotExist) as e:
              render_to_string(
                  ["template_loader/unknown.html", "template_loader/missing.html"]
              )
          self.assertEqual(
              e.exception.chain[0].tried[0][0].template_name,
              "template_loader/unknown.html",
          )
          self.assertEqual(e.exception.chain[0].backend.name, "dummy")
          self.assertEqual(
              e.exception.chain[1].tried[0][0].template_name,
              "template_loader/unknown.html",
          )
          self.assertEqual(e.exception.chain[1].backend.name, "django")
          self.assertEqual(
              e.exception.chain[2].tried[0][0].template_name,
              "template_loader/missing.html",
          )
          self.assertEqual(e.exception.chain[2].backend.name, "dummy")
          self.assertEqual(
              e.exception.chain[3].tried[0][0].template_name,
              "template_loader/missing.html",
          )
          self.assertEqual(e.exception.chain[3].backend.name, "django")
  
      def test_render_to_string_with_list_tries_all_engines_before_names(self):
          content = render_to_string(
              ["template_loader/goodbye.html", "template_loader/hello.html"]
          )
          self.assertEqual(content, "Goodbye! (Django templates)\n")
  