tox: Run flake8 on tests too

There's only one issue that needs fixing, thankfully.

Signed-off-by: Stephen Finucane <stephen@that.guru>

Author: stephenfin

tests/test_patch.py

@@ -392,7 +392,8 @@ def test_list_with_multiple_filters(self, mock_log, mock_echo, mock_index,
         assert mock_log.warning.called
 
     @mock.patch('git_pw.api.LOG')
-    def test_list_api_v1_1(self, mock_log, mock_echo, mock_index, mock_version):
+    def test_list_api_v1_1(self, mock_log, mock_echo, mock_index,
+                           mock_version):
         """Validate behavior with API v1.1."""
 
         mock_version.return_value = (1, 1)

tox.ini

@@ -11,10 +11,11 @@ commands =
   pytest -Wall {posargs}
 
 [testenv:pep8]
+skip_install = true
 deps =
   flake8
 commands =
-  flake8 {posargs} git_pw
+  flake8 {posargs:git_pw tests}
 
 [testenv:mypy]
 deps=