[1.8.x] Fixed #25079 -- Added warning if both TEMPLATES and TEMPLATE_* settings are defined.

Django ignores the value of the TEMPLATE_* settings if TEMPLATES is also
set, which is confusing for users following older tutorials. This change
adds a system check that warns if any of the TEMPLATE_* settings have
changed from their defaults but the TEMPLATES dict is also non-empty.

Removed the TEMPLATE_DIRS from the test settings file; this was marked
for removal in 1.10 but no tests fail if it is removed now.

Backport of 24620d71f2116da31abe6c9391f7bc807ac23c0b from master

2 files changed, 29 insertions, 4 deletions

diff --git a/tests/check_framework/tests_1_8_compatibility.py b/tests/check_framework/tests_1_8_compatibility.py
new file mode 100644
index 0000000000..8f354b6b3a
--- /dev/null
+++ b/tests/check_framework/tests_1_8_compatibility.py
@@ -0,0 +1,29 @@
+from django.core.checks.compatibility.django_1_8_0 import \
+    check_duplicate_template_settings
+from django.test import SimpleTestCase
+from django.test.utils import override_settings
+
+
+class CheckDuplicateTemplateSettingsTest(SimpleTestCase):
+
+    def test_not_raised_if_no_templates_setting(self):
+        self.assertEqual(check_duplicate_template_settings(None), [])
+
+    @override_settings(
+        TEMPLATES=[{'BACKEND': 'django.template.backends.django.DjangoTemplates'}],
+        TEMPLATE_DIRS=['/path/to/dirs'],
+    )
+    def test_duplicate_setting(self):
+        result = check_duplicate_template_settings(None)
+        self.assertEqual(result[0].id, '1_8.W001')
+
+    @override_settings(
+        TEMPLATES=[{'BACKEND': 'django.template.backends.django.DjangoTemplates'}],
+        TEMPLATE_DIRS=['/path/to/dirs'],
+        TEMPLATE_DEBUG=True,
+    )
+    def test_multiple_duplicate_settings(self):
+        result = check_duplicate_template_settings(None)
+        self.assertEqual(len(result), 1)
+        self.assertTrue('TEMPLATE_DIRS' in result[0].msg)
+        self.assertTrue('TEMPLATE_DEBUG' in result[0].msg)
diff --git a/tests/runtests.py b/tests/runtests.py
index dc7f7c9532..7fdc227018 100755
--- a/tests/runtests.py
+++ b/tests/runtests.py
@@ -111,8 +111,6 @@ def setup(verbosity, test_labels):
     state = {
         'INSTALLED_APPS': settings.INSTALLED_APPS,
         'ROOT_URLCONF': getattr(settings, "ROOT_URLCONF", ""),
-        # Remove the following line in Django 1.10.
-        'TEMPLATE_DIRS': settings.TEMPLATE_DIRS,
         'TEMPLATES': settings.TEMPLATES,
         'LANGUAGE_CODE': settings.LANGUAGE_CODE,
         'STATIC_URL': settings.STATIC_URL,
@@ -125,8 +123,6 @@ def setup(verbosity, test_labels):
     settings.ROOT_URLCONF = 'urls'
     settings.STATIC_URL = '/static/'
     settings.STATIC_ROOT = os.path.join(TMPDIR, 'static')
-    # Remove the following line in Django 1.10.
-    settings.TEMPLATE_DIRS = (TEMPLATE_DIR,)
     settings.TEMPLATES = [{
         'BACKEND': 'django.template.backends.django.DjangoTemplates',
         'DIRS': [TEMPLATE_DIR],