Add Ruff and pre-commit checks

.github/workflows/ruff.yml

@@ -0,0 +1,57 @@
+name: Ruff
+
+permissions:
+  contents: read
+
+on:
+  push:
+    branches:
+      - '**'
+
+  pull_request:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  lint:
+    name: ruff check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+
+      - name: Determine changed Python files
+        id: changed
+        run: |
+          if [ "${{ github.event_name }}" = "pull_request" ]; then
+            base="origin/${{ github.event.pull_request.base.ref }}"
+          else
+            base="${{ github.event.before }}"
+            # New branch or force-push: 'before' may not exist locally (or be all-zeros).
+            if ! git cat-file -e "$base" 2>/dev/null; then
+              base="HEAD^"
+              git cat-file -e "$base" 2>/dev/null || base=""
+            fi
+          fi
+
+          if [ -z "$base" ]; then
+            files=$(git ls-files '*.py' | xargs)
+          else
+            files=$(git diff --name-only --diff-filter=ACMR "$base"...HEAD -- '*.py' | xargs)
+          fi
+
+          echo "files=$files" >> "$GITHUB_OUTPUT"
+
+      - name: Install uv
+        if: steps.changed.outputs.files != ''
+        uses: astral-sh/setup-uv@v7
+        with:
+          version: "latest"
+
+      - name: Run ruff
+        if: steps.changed.outputs.files != ''
+        run: |
+          uvx ruff@0.16.1 check --config lint.per-file-ignores={} --output-format=github ${{ steps.changed.outputs.files }}

.pre-commit-config.yaml

@@ -0,0 +1,19 @@
+default_install_hook_types: [pre-commit, pre-push]
+
+repos:
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.16.1
+    hooks:
+      - id: ruff
+        args: [--config, "lint.per-file-ignores={}"]
+        stages: [pre-push]
+
+  - repo: local
+    hooks:
+      - id: pytest
+        name: pytest
+        entry: uv run pytest
+        language: system
+        pass_filenames: false
+        always_run: true
+        stages: [pre-push]

chainladder/tails/tests/test_constant.py

@@ -1,7 +1,4 @@
 import chainladder as cl
-import numpy as np
-from chainladder.utils.cupy import cp
-
 
 def test_constant_balances(qtr):
     xp = qtr.get_array_module()

pyproject.toml

@@ -50,12 +50,14 @@ Repository = "https://github.com/casact/chainladder-python"
 dev = [
     "lxml",
     "pytest",
-    "pytest-cov", 
+    "pytest-cov",
     "pytest-xdist",
     "jinja2",
     "ipython",
     "ipykernel",
     "pyright",
+    "ruff",
+    "pre-commit",
 ]
 docs = [
     "sphinx",
@@ -95,6 +97,65 @@ all = [
 testpaths = ["chainladder", "docs/_ext"]
 pythonpath = ["docs/_ext"]
 
+[tool.ruff]
+target-version = "py310"
+
+[tool.ruff.lint]
+select = ["E4", "E7", "E9", "F"]
+
+# Grandfathered violations that predate enabling this rule set. New and
+# newly-touched code is still held to the full ruleset above; these files
+# are exempted only from the specific codes they already violated so the
+# check can be required without blocking unrelated PRs. Remove entries as
+# files are cleaned up.
+[tool.ruff.lint.per-file-ignores]
+"chainladder/adjustments/bootstrap.py" = ["E721", "E722", "F841"]
+"chainladder/adjustments/disposal.py" = ["F401"]
+"chainladder/adjustments/tests/test_berqsherm.py" = ["F841"]
+"chainladder/adjustments/tests/test_disposal.py" = ["F841"]
+"chainladder/adjustments/trend.py" = ["F401"]
+"chainladder/core/base.py" = ["E721"]
+"chainladder/core/common.py" = ["F401"]
+"chainladder/core/correlation.py" = ["E741"]
+"chainladder/core/dunders.py" = ["E721", "E722", "F841"]
+"chainladder/core/io.py" = ["E731"]
+"chainladder/core/pandas.py" = ["E721", "F841"]
+"chainladder/core/slice.py" = ["E712", "E721", "E741"]
+"chainladder/core/tests/rtest_correlation.py" = ["E722", "F821"]
+"chainladder/core/tests/test_arithmetic.py" = ["E711"]
+"chainladder/core/tests/test_display.py" = ["E722"]
+"chainladder/core/tests/test_grain.py" = ["F401", "F841"]
+"chainladder/core/tests/test_triangle.py" = ["E712", "E721", "F811", "F841"]
+"chainladder/core/triangle.py" = ["E712", "E721", "E731", "F401", "F841"]
+"chainladder/development/base.py" = ["E712", "F401", "F841"]
+"chainladder/development/clark.py" = ["E721", "E731"]
+"chainladder/development/constant.py" = ["E712"]
+"chainladder/development/glm.py" = ["F401"]
+"chainladder/development/incremental.py" = ["E721", "F401"]
+"chainladder/development/learning.py" = ["E711", "F401"]
+"chainladder/development/tests/rtest_clark.py" = ["E722"]
+"chainladder/development/tests/rtest_development.py" = ["E722", "F401"]
+"chainladder/development/tests/rtest_munich.py" = ["E722", "F401"]
+"chainladder/development/tests/test_constant.py" = ["F841"]
+"chainladder/development/tests/test_development.py" = ["E722"]
+"chainladder/development/tests/test_incremental.py" = ["F841"]
+"chainladder/development/tests/test_munich.py" = ["F841"]
+"chainladder/methods/base.py" = ["F401"]
+"chainladder/methods/capecod.py" = ["F401"]
+"chainladder/methods/mack.py" = ["F401"]
+"chainladder/methods/tests/rtest_mack.py" = ["E722", "F401"]
+"chainladder/tails/bondy.py" = ["F401"]
+"chainladder/tails/curve.py" = ["E721", "F401"]
+"chainladder/tails/tests/rtest_exponential.py" = ["E722", "F401"]
+"chainladder/tails/tests/test_constant.py" = ["F401"]
+"chainladder/utils/cupy.py" = ["E722", "F401"]
+"chainladder/utils/dask.py" = ["E722", "E741"]
+"chainladder/utils/sparse.py" = ["E721"]
+"chainladder/utils/tests/test_utilities.py" = ["E712", "E741", "F811", "F841"]
+"chainladder/utils/triangle_weight.py" = ["F401"]
+"chainladder/utils/utility_functions.py" = ["E721", "F401"]
+"chainladder/workflow/tests/test_voting.py" = ["E731"]
+
 [tool.setuptools]
 include-package-data = true