Add Black

script/bootstrap

@@ -7,4 +7,4 @@ set -e
 cd "$(dirname "$0")/.."
 
 echo "Installing test dependencies..."
-python3 -m pip install tox colorlog
+python3 -m pip install tox colorlog pre-commit

script/check_format

@@ -0,0 +1,10 @@
+#!/bin/sh
+# Format code with black.
+
+cd "$(dirname "$0")/.."
+
+black \
+  --check \
+  --fast \
+  --quiet \
+  homeassistant tests script

script/setup

@@ -7,4 +7,5 @@ set -e
 cd "$(dirname "$0")/.."
 script/bootstrap
 
+pre-commit install
 pip3 install -e .