Add black to dev dependencies and tox lint

Author: Ben Dickinson

pyproject.toml

@@ -59,6 +59,7 @@ mkdocs-material = "^5.5.14"
 pymdown-extensions = "^8.0"
 mkdocs-git-revision-date-plugin = "^0.3.1"
 mkdocs-redirects = "^1.0.3"
+black = "^21.12b0"
 
 [tool.isort]
 known_first_party = "pattern_library"

tox.ini

@@ -23,6 +23,7 @@ commands =
     poetry install -q
     poetry run flake8
     poetry run isort --check-only --diff
+    poetry run black --check .
 
 [flake8]
 ignore = C901,W503