Add django_debug_mode to configure how DEBUG is set in tests

Fixes #846.

Author: bluetech

docs/usage.rst

@@ -29,6 +29,25 @@ Additional command line options
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Fail tests that render templates which make use of invalid template variables.
 
+Additional pytest.ini settings
+------------------------------
+
+``django_debug_mode`` - change how DEBUG is set
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+By default tests run with the
+`DEBUG <https://docs.djangoproject.com/en/stable/ref/settings/#debug>`_
+setting set to ``False``. This is to ensure that the observed output of your
+code matches what will be seen in a production setting.
+
+If you want ``DEBUG`` to be set::
+
+    [pytest]
+    django_debug_mode = true
+
+You can also use ``django_debug_mode = keep`` to disable the overriding and use
+whatever is already set in the Django settings.
+
 Running tests in parallel with pytest-xdist
 -------------------------------------------
 pytest-django supports running tests on multiple processes to speed up test

pytest_django/plugin.py

@@ -118,6 +118,12 @@ def pytest_addoption(parser):
         type="bool",
         default=True,
     )
+    parser.addini(
+        "django_debug_mode",
+        "How to set the Django DEBUG setting (default `False`). "
+        "Use `keep` to not override.",
+        default="False",
+    )
     group.addoption(
         "--fail-on-template-vars",
         action="store_true",
@@ -447,7 +453,13 @@ def django_test_environment(request):
         _setup_django()
         from django.test.utils import setup_test_environment, teardown_test_environment
 
-        setup_test_environment(debug=False)
+        debug_ini = request.config.getini("django_debug_mode")
+        if debug_ini == "keep":
+            debug = None
+        else:
+            debug = _get_boolean_value(debug_ini, False)
+
+        setup_test_environment(debug=debug)
         request.addfinalizer(teardown_test_environment)
 
 

tests/test_django_settings_module.py

@@ -278,7 +278,7 @@ def test_settings():
     assert result.ret == 0
 
 
-def test_debug_false(testdir, monkeypatch):
+def test_debug_false_by_default(testdir, monkeypatch):
     monkeypatch.delenv("DJANGO_SETTINGS_MODULE")
     testdir.makeconftest(
         """
@@ -307,6 +307,78 @@ def test_debug_is_false():
     assert r.ret == 0
 
 
+@pytest.mark.parametrize('django_debug_mode', (False, True))
+def test_django_debug_mode_true_false(testdir, monkeypatch, django_debug_mode):
+    monkeypatch.delenv("DJANGO_SETTINGS_MODULE")
+    testdir.makeini(
+        """
+       [pytest]
+       django_debug_mode = {}
+    """.format(django_debug_mode)
+    )
+    testdir.makeconftest(
+        """
+        from django.conf import settings
+
+        def pytest_configure():
+            settings.configure(SECRET_KEY='set from pytest_configure',
+                               DEBUG=%s,
+                               DATABASES={'default': {
+                                   'ENGINE': 'django.db.backends.sqlite3',
+                                   'NAME': ':memory:'}},
+                               INSTALLED_APPS=['django.contrib.auth',
+                                               'django.contrib.contenttypes',])
+    """ % (not django_debug_mode)
+    )
+
+    testdir.makepyfile(
+        """
+        from django.conf import settings
+        def test_debug_is_false():
+            assert settings.DEBUG is {}
+    """.format(django_debug_mode)
+    )
+
+    r = testdir.runpytest_subprocess()
+    assert r.ret == 0
+
+
+@pytest.mark.parametrize('settings_debug', (False, True))
+def test_django_debug_mode_keep(testdir, monkeypatch, settings_debug):
+    monkeypatch.delenv("DJANGO_SETTINGS_MODULE")
+    testdir.makeini(
+        """
+       [pytest]
+       django_debug_mode = keep
+    """
+    )
+    testdir.makeconftest(
+        """
+        from django.conf import settings
+
+        def pytest_configure():
+            settings.configure(SECRET_KEY='set from pytest_configure',
+                               DEBUG=%s,
+                               DATABASES={'default': {
+                                   'ENGINE': 'django.db.backends.sqlite3',
+                                   'NAME': ':memory:'}},
+                               INSTALLED_APPS=['django.contrib.auth',
+                                               'django.contrib.contenttypes',])
+    """ % settings_debug
+    )
+
+    testdir.makepyfile(
+        """
+        from django.conf import settings
+        def test_debug_is_false():
+            assert settings.DEBUG is {}
+    """.format(settings_debug)
+    )
+
+    r = testdir.runpytest_subprocess()
+    assert r.ret == 0
+
+
 @pytest.mark.django_project(
     extra_settings="""
     INSTALLED_APPS = [