Print git-diff when pre-commit fails

When pre-commit fails and automatically fixes issues for us in Jenkins
we are not able to see what pre-commit automatically fixed. Adding
--show-diff-on-failure makes pre-commit perform a git-diff immediately
after failing to ensure more useful output is printed to inform the
contributor what changes are needed to pass the check.

Signed-off-by: Thanh Ha <zxiiro@gmail.com>
Change-Id: Icd6484c8c4157d38885b1de460517d9b656a06d7

diff --git a/tox.ini b/tox.ini
index 6fc52f1..2a532c9 100644 (file)
--- a/tox.ini
+++ b/tox.ini
@@ -64,7 +64,7 @@ description = Precommit checks for black, gitlint, etc.
 basepython = python3
 deps = pre-commit
 commands =
-    pre-commit run --all-files
+    pre-commit run --all-files --show-diff-on-failure
 
 [testenv:reno]
 description = OpenStack Reno checks