fixing linter errors

Author: dantownsend

piccolo/columns/column_types.py

@@ -4,7 +4,7 @@
 import typing as t
 import uuid
 
-from piccolo.columns.base import Column, OnDelete, OnUpdate
+from piccolo.columns.base import Column, OnDelete, OnUpdate, ForeignKeyMeta
 from piccolo.querystring import Unquoted
 
 if t.TYPE_CHECKING:
@@ -198,6 +198,12 @@ class ForeignKey(Integer):
 
     column_type = "INTEGER"
 
+    # This is here just for type inference - the actual value is set by the
+    # Table metaclass.
+    _foreign_key_meta = ForeignKeyMeta(
+        Table, OnDelete.cascade, OnUpdate.cascade
+    )
+
     def __init__(
         self,
         references: t.Union[t.Type[Table], str],

tests/columns/test_smallint.py

@@ -36,7 +36,7 @@ def test_length(self):
         row.value = min_value
         row.save().run_sync()
 
-        if not "TRAVIS" in os.environ:
+        if "TRAVIS" not in os.environ:
             # This stalls out on Travis - not sure why.
             with self.assertRaises(Exception):
                 row.value = max_value + 100