Better output on linter failure in CI (#478)

Co-authored-by: Brett Cannon <brett@python.org>

Author: henryiii

.github/workflows/lint.yml

@@ -31,7 +31,7 @@ jobs:
           cache: "pip"
 
       - name: Run `nox -s lint`
-        run: pipx run nox --error-on-missing-interpreters -s lint
+        run: pipx run nox --error-on-missing-interpreters -s lint -- --show-diff-on-failure
 
   build:
     name: Build sdist and wheel

noxfile.py

@@ -57,7 +57,7 @@ def coverage(*args):
 def lint(session):
     # Run the linters (via pre-commit)
     session.install("pre-commit")
-    session.run("pre-commit", "run", "--all-files")
+    session.run("pre-commit", "run", "--all-files", *session.posargs)
 
     # Check the distribution
     session.install("build", "twine")