CP-3580: add coverage gate to squawk-pre-commit

.github/workflows/ci.yml

@@ -76,8 +76,22 @@ jobs:
             fi
           fi
 
-      - name: Run tests
-        run: poetry run pytest tests/ -v
+      - name: Run tests with coverage
+        run: |
+          poetry run pytest tests/ -v \
+            --cov=squawk_alembic \
+            --cov-report=xml \
+            --cov-report=term-missing \
+            --cov-fail-under=95
+
+      - name: Enforce diff coverage on changed lines
+        if: github.event_name == 'pull_request'
+        run: |
+          # diff-cover needs main's history to compute the merge-base for the PR diff.
+          git fetch origin main
+          poetry run diff-cover coverage.xml \
+            --compare-branch=origin/main \
+            --fail-under=80
 
   auto-tag:
     needs: lint-and-test

.gitignore

@@ -18,6 +18,7 @@ dist/
 # Test / coverage
 .pytest_cache/
 .coverage
+coverage.xml
 htmlcov/
 
 # Editors / OS

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "poetry.core.masonry.api"
 
 [tool.poetry]
 name = "squawk-alembic"
-version = "0.3.4"
+version = "0.3.5"
 description = "Pre-commit hook to lint Alembic migration SQL with squawk"
 packages = [{include = "squawk_alembic"}]
 readme = "README.md"
@@ -35,6 +35,7 @@ pytest = "~=9.0.3"
 ruff = "~=0.13.3"
 pyrefly = "~=1.1.1"
 pytest-cov = "~=7.1.0"
+diff-cover = "~=10.2.1"
 
 [tool.poetry.scripts]
 squawk-alembic = "squawk_alembic.hook:main"

squawk_alembic/__init__.py

@@ -1 +1 @@
-__version__ = "0.3.4"
+__version__ = "0.3.5"