From e7d7c1f4b76e112ed7e5d32cf4e053fb69cbc121 Mon Sep 17 00:00:00 2001
From: Chandan Singh <csingh43@bloomberg.net>
Date: Tue, 5 Nov 2019 12:59:51 +0000
Subject: Add configuration to run Black

Introduce two new tox environments - `format` and `format-check`. The
`format` environment will reformat the code using `black` whereas the
`format-check` envrionment will simply print the diff without modifying
any files.

Configure Black to use the same line lengths that we use
currently, i.e. 119.
---
 pyproject.toml | 18 ++++++++++++++++++
 tox.ini        | 20 ++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/pyproject.toml b/pyproject.toml
index 4dd02d1e5..29f5589b5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -7,3 +7,21 @@ requires = [
     "Cython"
 ]
 build-backend = "setuptools.build_meta"
+
+[tool.black]
+line-length = 119
+exclude = '''
+(
+  /(
+      \.eggs
+    | \.git
+    | \.mypy_cache
+    | \.tox
+    | _build
+    | build
+    | dist
+  )/
+  | src/buildstream/_fuse
+  | src/buildstream/_protos
+)
+'''
diff --git a/tox.ini b/tox.ini
index 4c18f2c14..d8fa3e984 100644
--- a/tox.ini
+++ b/tox.ini
@@ -102,6 +102,26 @@ deps =
 setenv =
     COVERAGE_FILE = {toxinidir}/.coverage-reports/.coverage
 
+#
+# Code formatters
+#
+[testenv:format]
+skip_install = True
+deps =
+    black==19.10b0
+commands =
+    black {posargs: src tests}
+
+#
+# Code format checkers
+#
+[testenv:format-check]
+skip_install = True
+deps =
+    black==19.10b0
+commands =
+    black --check --diff {posargs: src tests}
+
 #
 # Running linters
 #
-- 
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