Add black to CI

3 files changed, 25 insertions, 4 deletions

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 0bd0a44..03f9482 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,5 +1,18 @@
 image: registry.gitlab.com/reidrac/ubox-msx-lib-ci:latest
 
-build-and-test:
+stages:
+  - lint
+  - build
+  - test
+
+lint:
+  script:
+    - black --check --diff .
+
+build:
+  script:
+    - make game
+
+test:
   script:
     - make test
diff --git a/README.md b/README.md
index 903184b..15e9863 100644
--- a/README.md
+++ b/README.md
@@ -105,6 +105,15 @@ Some advice if you want to make a successful contribution:
  - Get early feedback, specially when working on a large contribution
  - Contributions always require a pull request and a review
 
+### Formatting
+
+This project uses [Black](https://github.com/psf/black) to format the Python
+code, and this is checked in CI.
+
+Before submitting any code to review, ensure you have installed Black 22.1.0 and run:
+
+    black .
+
 ## Authors
 
 This was mostly written by Juan J. Martinez during the development of
diff --git a/tests/test_rom.py b/tests/test_rom.py
index d980dad..30e8d33 100755
--- a/tests/test_rom.py
+++ b/tests/test_rom.py
@@ -31,9 +31,8 @@ class TestRom(unittest.TestCase):
         self.assertEqual(len(self.data), self.ROM_SIZE)
 
     def test_header_main_init_address(self):
-        self.assertEqual(struct.unpack(
-            "<H", self.data[2:4]), (self.main_init,))
+        self.assertEqual(struct.unpack("<H", self.data[2:4]), (self.main_init,))
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     unittest.main()