Switch code formatter from Black to Ruff (#547)

* Switch code formatter from Black to Ruff

Replace black and linecheck with ruff for code formatting:
- Remove black[jupyter] and linecheck dependencies, add ruff>=0.9.0
- Update Makefile format target to use ruff format
- Replace lgeiger/black-action in CI with ruff format --check
- Add [tool.ruff] config with line-length=88 to pyproject.toml
- Add towncrier changelog fragment
- Reformat all files with ruff

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Reformat .github/bump_version.py with ruff

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: MaxGhenis

.github/bump_version.py

@@ -19,9 +19,7 @@ def get_current_version(pyproject_path: Path) -> str:
 
 def infer_bump(changelog_dir: Path) -> str:
     fragments = [
-        f
-        for f in changelog_dir.iterdir()
-        if f.is_file() and f.name != ".gitkeep"
+        f for f in changelog_dir.iterdir() if f.is_file() and f.name != ".gitkeep"
     ]
     if not fragments:
         print("No changelog fragments found", file=sys.stderr)

.github/workflows/pr.yaml

@@ -7,10 +7,15 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: Check formatting
-        uses: "lgeiger/black-action@master"
+      - name: Set up Python
+        uses: actions/setup-python@v5
         with:
-          args: ". -l 79 --check"
+          python-version: "3.14"
+          allow-prereleases: true
+      - name: Install ruff
+        run: pip install "ruff>=0.9.0"
+      - name: Check formatting
+        run: ruff format --check .
   check-changelog:
     name: Check changelog fragment
     runs-on: ubuntu-latest

.github/workflows/push.yaml

@@ -10,10 +10,15 @@ jobs:
       && (github.event.head_commit.message == 'Update PolicyEngine Canada')
     steps:
       - uses: actions/checkout@v4
-      - name: Check formatting
-        uses: "lgeiger/black-action@master"
+      - name: Set up Python
+        uses: actions/setup-python@v5
         with:
-          args: ". -l 79 --check"
+          python-version: "3.14"
+          allow-prereleases: true
+      - name: Install ruff
+        run: pip install "ruff>=0.9.0"
+      - name: Check formatting
+        run: ruff format --check .
   versioning:
     name: Update versioning
     if: |

Makefile

@@ -5,8 +5,7 @@ documentation:
 	jupyter-book build docs
 
 format:
-	black . -l 79
-	linecheck . --fix
+	ruff format .
 
 install:
 	pip install -e .[dev]

changelog.d/switch-to-ruff.changed.md

@@ -0,0 +1 @@
+Switch code formatter from Black to Ruff.

policyengine_canada/data/datasets/country_template_dataset.py

@@ -10,11 +10,7 @@ class CountryTemplateDataset(Dataset):
     label = "Country template dataset"
     folder_path = COUNTRY_DIR / "data" / "storage"
     data_format = Dataset.TIME_PERIOD_ARRAYS
-    file_path = (
-        Path(__file__).parent.parent
-        / "storage"
-        / "country_template_dataset.h5"
-    )
+    file_path = Path(__file__).parent.parent / "storage" / "country_template_dataset.h5"
 
     # The generation function is the most important part: it defines
     # how the dataset is generated from the raw data for a given year.

policyengine_canada/variables/gov/cra/benefits/ccb/child_benefit_base_person.py

@@ -13,6 +13,4 @@ def formula(person, period, parameters):
         age = person("age", period)
         p = parameters(period).gov.cra.benefits.ccb
         full_custody = person("full_custody", period)
-        return where(
-            full_custody, p.base.calc(age), p.base.calc(age) / p.divisor
-        )
+        return where(full_custody, p.base.calc(age), p.base.calc(age) / p.divisor)

policyengine_canada/variables/gov/cra/benefits/cwb/disability_supplement/cwb_disability_category.py

@@ -20,9 +20,7 @@ def formula(household, period, parameters):
         person = household.members
         # Compute individual-level eligibility among heads/spouses.
         head_or_spouse = person("is_head_or_spouse", period)
-        disability_eligible = person(
-            "cwb_disability_supplement_eligible", period
-        )
+        disability_eligible = person("cwb_disability_supplement_eligible", period)
         cwb_family = household("is_cwb_family", period)
         eligible_spouses = household.sum(head_or_spouse * disability_eligible)
         return select(

policyengine_canada/variables/gov/cra/benefits/cwb/disability_supplement/cwb_disability_supplement_eligible.py

@@ -6,9 +6,7 @@ class cwb_disability_supplement_eligible(Variable):
     entity = Person
     label = "Eligible for canada workers benefit supplement"
     definition_period = YEAR
-    reference = (
-        "https://laws-lois.justice.gc.ca/eng/acts/I-3.3/page-89.html#docCont"
-    )
+    reference = "https://laws-lois.justice.gc.ca/eng/acts/I-3.3/page-89.html#docCont"
 
     def formula(person, period, parameters):
         # For now, apply a person-level logic based on age.

policyengine_canada/variables/gov/cra/benefits/cwb/disability_supplement/cwb_disability_supplement_max_amount.py

@@ -6,15 +6,11 @@ class cwb_disability_supplement_max_amount(Variable):
     entity = Household
     label = "Eligible for canada workers benefit supplement"
     definition_period = YEAR
-    reference = (
-        "https://laws-lois.justice.gc.ca/eng/acts/I-3.3/page-89.html#docCont"
-    )
+    reference = "https://laws-lois.justice.gc.ca/eng/acts/I-3.3/page-89.html#docCont"
     unit = CAD
 
     def formula(household, period, parameters):
         person = household.members
         eligible = person("cwb_disability_supplement_eligible", period)
-        amount = parameters(
-            period
-        ).gov.cra.benefits.cwb.amount.disability_supplement
+        amount = parameters(period).gov.cra.benefits.cwb.amount.disability_supplement
         return household.sum(eligible * amount)