Be more careful to not load Django when settings is not properly

configured.

When another plugin(or conftest) imports Django, there might be errors
arising. Importing Django before pytest-django has the chance to
configure settings and call django.setup() may be an error, but it may
also be correct depending on what gets imported.

This commit closes pytest-dev#289.

Author: pelme

docs/changelog.rst

@@ -1,5 +1,12 @@
 Changelog
 =========
+
+NEXT
+----
+* Fix error when Django happens to be imported before pytest-django runs.
+  Thanks to Will Harris for `the bug report
+  <https://github.com/pytest-dev/pytest-django/issues/289>`_.
+
 2.9.1
 -----
 

pytest_django/plugin.py

@@ -128,7 +128,11 @@ def _setup_django():
     if 'django' not in sys.modules:
         return
 
-    import django
+    import django.conf
+
+    # Avoid trying to force-load Django when settings is not properly configured
+    if not django.conf.settings.configured:
+        return
 
     if hasattr(django, 'setup'):
         django.setup()

tests/test_django_settings_module.py

@@ -340,3 +340,12 @@ def test_cfg(pytestconfig):
     """)
     r = testdir.runpytest_subprocess('-s')
     assert r.ret == 0
+
+
+def test_no_django_settings_but_django_imported(testdir, monkeypatch):
+    """Make sure we do not crash when Django happens to be imported, but
+    settings is not properly configured"""
+    monkeypatch.delenv('DJANGO_SETTINGS_MODULE')
+    testdir.makeconftest('import django')
+    r = testdir.runpytest_subprocess('--help')
+    assert r.ret == 0