[1.7.x] Adjusted refactoring of vendor checks.

Thanks Shai for the thorough review.

Backport of fb90b7c from master

django/db/backends/__init__.py

@@ -616,8 +616,6 @@ class BaseDatabaseFeatures(object):
     supports_subqueries_in_group_by = True
     supports_bitwise_or = True
 
-    supports_boolean_type = True
-
     supports_binary_field = True
 
     # Do time/datetime fields have microsecond precision?
@@ -679,6 +677,9 @@ class BaseDatabaseFeatures(object):
     # Can the backend introspect an BinaryField, instead of an TextField?
     can_introspect_binary_field = True
 
+    # Can the backend introspect an BooleanField, instead of an IntegerField?
+    can_introspect_boolean_field = True
+
     # Can the backend introspect an IPAddressField, instead of an CharField?
     can_introspect_ip_address_field = False
 
@@ -737,7 +738,7 @@ class BaseDatabaseFeatures(object):
     # Suffix for backends that don't support "SELECT xxx;" queries.
     bare_select_suffix = ''
 
-    lowercases_column_names = False
+    uppercases_column_names = True
 
     def __init__(self, connection):
         self.connection = connection

django/db/backends/mysql/base.py

@@ -172,13 +172,13 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     has_select_for_update_nowait = False
     supports_forward_references = False
     supports_long_model_names = False
-    supports_boolean_type = False
     # XXX MySQL DB-API drivers currently fail on binary data on Python 3.
     supports_binary_field = six.PY2
     supports_microsecond_precision = False
     supports_regex_backreferencing = False
     supports_date_lookup_using_string = False
     can_introspect_binary_field = False
+    can_introspect_boolean_field = False
     supports_timezones = False
     requires_explicit_null_ordering_when_grouping = True
     allows_auto_pk_0 = False

django/db/backends/oracle/base.py

@@ -120,7 +120,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     connection_persists_old_columns = True
     closed_cursor_error_class = InterfaceError
     bare_select_suffix = " FROM DUAL"
-    lowercases_column_names = True
+    uppercases_column_names = False
 
 
 class DatabaseOperations(BaseDatabaseOperations):

tests/inspectdb/tests.py

@@ -87,7 +87,7 @@ class InspectDBTestCase(TestCase):
         else:
             assertFieldType('big_int_field', "models.IntegerField()")
 
-        if connection.features.supports_boolean_type:
+        if connection.features.can_introspect_boolean_field:
             assertFieldType('bool_field', "models.BooleanField()")
             assertFieldType('null_bool_field', "models.NullBooleanField()")
         else:
@@ -176,7 +176,7 @@ class InspectDBTestCase(TestCase):
         out = StringIO()
         call_command('inspectdb', stdout=out)
         output = out.getvalue()
-        base_name = 'field' if connection.features.lowercases_column_names else 'Field'
+        base_name = 'field' if not connection.features.uppercases_column_names else 'Field'
         self.assertIn("field = models.IntegerField()", output)
         self.assertIn("field_field = models.IntegerField(db_column='%s_')" % base_name, output)
         self.assertIn("field_field_0 = models.IntegerField(db_column='%s__')" % base_name, output)

tests/introspection/tests.py

@@ -57,7 +57,8 @@ class IntrospectionTests(TestCase):
         self.assertEqual(
             [datatype(r[1], r) for r in desc],
             ['AutoField' if connection.features.can_introspect_autofield else 'IntegerField',
-             'CharField', 'CharField', 'CharField', 'BigIntegerField',
+             'CharField', 'CharField', 'CharField',
+             'BigIntegerField' if connection.features.can_introspect_big_integer_field else 'IntegerField',
              'BinaryField' if connection.features.can_introspect_binary_field else 'TextField']
         )
 

tests/serializers_regress/tests.py

@@ -449,6 +449,7 @@ class SerializerTests(TestCase):
         self.assertEqual(base_data, proxy_proxy_data.replace('proxy', ''))
 
 
+@skipUnlessDBFeature('supports_binary_field')
 def serializerTest(format, self):
 
     # Create all the objects defined in the test data
@@ -481,8 +482,6 @@ def serializerTest(format, self):
     for klass, count in instance_count.items():
         self.assertEqual(count, klass.objects.count())
 
-serializerTest = skipUnlessDBFeature('supports_binary_field')(serializerTest)
-
 
 def naturalKeySerializerTest(format, self):
     # Create all the objects defined in the test data