from django.core.exceptions import ImproperlyConfigured

from django.template import engines

from django.test import SimpleTestCase, override_settings

class TemplateUtilsTests(SimpleTestCase):

    @override_settings(TEMPLATES=[{"BACKEND": "raise.import.error"}])

    def test_backend_import_error(self):

        """

        Failing to import a backend keeps raising the original import error

        (#24265).

        """

        with self.assertRaisesMessage(ImportError, "No module named 'raise"):

            engines.all()

        with self.assertRaisesMessage(ImportError, "No module named 'raise"):

            engines.all()

    @override_settings(

        TEMPLATES=[

            {

                "BACKEND": "django.template.backends.django.DjangoTemplates",

                # Incorrect: APP_DIRS and loaders are mutually incompatible.

                "APP_DIRS": True,

                "OPTIONS": {"loaders": []},

            }

        ]

    )

    def test_backend_improperly_configured(self):

        """

        Failing to initialize a backend keeps raising the original exception

        (#24265).

        """

        msg = "app_dirs must not be set when loaders is defined."

        with self.assertRaisesMessage(ImproperlyConfigured, msg):

            engines.all()

        with self.assertRaisesMessage(ImproperlyConfigured, msg):

            engines.all()

    @override_settings(

        TEMPLATES=[

            {

                "BACKEND": "django.template.backends.django.DjangoTemplates",

            },

            {

                "BACKEND": "django.template.backends.django.DjangoTemplates",

            },

        ]

    )

    def test_backend_names_must_be_unique(self):

        msg = (

            "Template engine aliases aren't unique, duplicates: django. Set "

            "a unique NAME for each engine in settings.TEMPLATES."

        )

        with self.assertRaisesMessage(ImproperlyConfigured, msg):

            engines.all()