Pass connection to db_type()

Author: adamchainz

tests/testapp/test_size_fields.py

@@ -50,7 +50,7 @@ def test_binaryfield_default_length(self):
         # By default, SizedBinaryField should act like BinaryField
         field = SizedBinaryField()
         assert field.size_class == 4
-        assert field.db_type(None) == "longblob"
+        assert field.db_type(connection) == "longblob"
 
     @atomic
     def test_binary_1_max_length(self):
@@ -153,7 +153,7 @@ def test_textfield_default_length(self):
         # By default, SizedTextField should act like TextField
         field = SizedTextField()
         assert field.size_class == 4
-        assert field.db_type(None) == "longtext"
+        assert field.db_type(connection) == "longtext"
 
     def test_tinytext_max_length(self):
         # Okay