Merge pull request #2 from David-Wobrock/master

Allow dropping a not null constraint

Author: jbbarth

django_better_migrations/rules.py

@@ -11,4 +11,7 @@ def process(self, migration, statements):
         return "OK"
 
     def _incorrect(self, stmt):
-        return stmt.startswith("ALTER TABLE") and "NOT NULL" in stmt
+        return (
+            stmt.startswith("ALTER TABLE") and
+            "NOT NULL" in stmt and
+            "DROP NOT NULL" not in stmt)

tests/test_rules.py

@@ -0,0 +1,23 @@
+import unittest
+
+from django_better_migrations.rules import NoAddColumnNonNull
+
+
+class TestAddColumnNonNullRules(unittest.TestCase):
+    def test_add_not_null_column(self):
+        statements = (
+            'ALTER TABLE "auth_user" ALTER COLUMN "username" NOT NULL;',
+        )
+        return_code = NoAddColumnNonNull().process(
+            None,
+            statements)
+        self.assertEquals(return_code, "ERROR")
+
+    def test_drop_not_null_column(self):
+        statements = (
+            'ALTER TABLE "auth_user" ALTER COLUMN "username" DROP NOT NULL;',
+        )
+        return_code = NoAddColumnNonNull().process(
+            None,
+            statements)
+        self.assertEquals(return_code, "OK")