Check if default_app_config is used on Django 1.7+

.gitignore

@@ -102,3 +102,6 @@ venv.bak/
 
 # mypy
 .mypy_cache/
+
+# IntelliJ
+.idea

README.md

@@ -40,6 +40,7 @@ $ pytest --cov=.
 | `DJ06` | ModelForm should not set exclude, instead it should use fields, which is an explicit list of all the fields that should be included in the form |
 | `DJ07` | ModelForm.Meta should not set fields to `__all__`|
 | `DJ08` | Models that inherits from django db models should set `__str__`|
+| `DJ09` | New applications should avoid default_app_config|
 
 ## Licence
 

flake8_django/checker.py

@@ -1,6 +1,7 @@
 import ast
 
-from flake8_django.checkers import ModelDunderStrMissingChecker, ModelFieldChecker, ModelFormChecker, URLChecker, RenderChecker
+from flake8_django.checkers import DefaultAppConfigChecker, ModelDunderStrMissingChecker, ModelFieldChecker, \
+    ModelFormChecker, URLChecker, RenderChecker
 
 __version__ = '0.0.3'
 
@@ -18,7 +19,10 @@ class DjangoStyleFinder(ast.NodeVisitor):
         'ClassDef': [
             ModelFormChecker(),
             ModelDunderStrMissingChecker(),
-        ]
+        ],
+        'Module': [
+            DefaultAppConfigChecker(),
+        ],
     }
 
     def __init__(self, *args, **kwargs):
@@ -38,6 +42,9 @@ def visit_Call(self, node):
     def visit_ClassDef(self, node):
         self.capture_issues_visitor('ClassDef', node)
 
+    def visit_Module(self, node):
+        self.capture_issues_visitor('Module', node)
+
 
 class DjangoStyleChecker(object):
     """

flake8_django/checkers/__init__.py

@@ -1,8 +1,9 @@
+from .default_app_config import DefaultAppConfigChecker
 from .model_dunder_str import ModelDunderStrMissingChecker
 from .model_fields import ModelFieldChecker
 from .model_form import ModelFormChecker
 from .render import RenderChecker
 from .urls import URLChecker
 
 
-__all__ = ['ModelDunderStrMissingChecker', 'ModelFieldChecker', 'ModelFormChecker', 'RenderChecker', 'URLChecker']
+__all__ = ['DefaultAppConfigChecker', 'ModelDunderStrMissingChecker', 'ModelFieldChecker', 'ModelFormChecker', 'RenderChecker', 'URLChecker']

flake8_django/checkers/default_app_config.py

@@ -0,0 +1,29 @@
+import ast
+
+import django
+
+from .checker import Checker
+from .issue import Issue
+
+
+class DJ09(Issue):
+    code = 'DJ09'
+    description = 'New applications should avoid default_app_config'
+
+
+class DefaultAppConfigChecker(Checker):
+
+    def run(self, node):
+        if django.VERSION < (1, 7):
+            return []
+        issues = []
+        for elem in node.body:
+            if not isinstance(elem, ast.Assign):
+                continue
+            target_names = map(lambda n: n.id == 'default_app_config', elem.targets)
+            if any(target_names):
+                issues.append(DJ09(
+                    elem.lineno,
+                    elem.col_offset,
+                ))
+        return issues

setup.py

@@ -28,7 +28,7 @@
         ],
     },
     install_requires=['flake8'],
-    tests_require=['pytest'],
+    tests_require=['django', 'pytest'],
     classifiers=[
         'Framework :: Flake8',
         'License :: OSI Approved :: MIT License',

tests/fixtures/default_app_config.py

@@ -0,0 +1 @@
+default_app_config = 'foobar'

tests/test_default_app_config.py

@@ -0,0 +1,16 @@
+import django
+
+from .utils import run_check, load_fixture_file
+
+
+def test_default_app_config_django_16(monkeypatch):
+    monkeypatch.setattr(django, 'VERSION', (1, 6))
+    code = load_fixture_file('default_app_config.py')
+    assert len(run_check(code)) == 0
+
+
+def test_default_app_config_django_17(monkeypatch):
+    monkeypatch.setattr(django, 'VERSION', (1, 7))
+    code = load_fixture_file('default_app_config.py')
+    assert len(run_check(code)) == 1
+    assert 'DJ09' in run_check(code)[0][2]

tox.ini

@@ -4,6 +4,8 @@ envlist = py34,py35,py36,py37
 max-line-length = 120
 exclude = tests/fixtures/*
 [testenv]
-deps = pytest
+deps =
+    pytest
+    django
 commands =
     pytest