build: adding lint target to tox

Author: pthierry-ledger

tox.ini

@@ -2,8 +2,8 @@
 min_version = 4.0
 env_list =
   unittests
-  genproto
   build
+  lint
 isolated_build = true
 
 [tox:.package]
@@ -43,6 +43,13 @@ commands =
     coverage report -m
     coverage xml
 
+[testenv:lint]
+extras = tests
+commands =
+    flake8  --docstring-convention=numpy
+    black --line-length 90 --check --diff .
+
+
 [testenv:flake8]
 commands=flake8 {posargs}
 
@@ -61,6 +68,7 @@ application-import-names = etcd3
 max-complexity = 10
 # TODO add docstrings for public methods, modules, etc
 ignore = D1, W503
+max-line-length = 90
 
 [pytest]
 tmp_path_retention_policy = none