Add pre-commit, style linting with ruff

Again, mostly copied from the approach used in
flask-debugtoolbar.

.pre-commit-config.yaml

@@ -0,0 +1,21 @@
+ci:
+  autoupdate_schedule: monthly
+repos:
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.4.2
+    hooks:
+      - id: ruff
+      - id: ruff-format
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.6.0
+    hooks:
+      - id: check-merge-conflict
+        exclude: "(codemirror|jquery)"
+      - id: debug-statements
+        exclude: "(codemirror|jquery)"
+      - id: fix-byte-order-marker
+        exclude: "(codemirror|jquery)"
+      - id: trailing-whitespace
+        exclude: "(codemirror|jquery)"
+      - id: end-of-file-fixer
+        exclude: "(codemirror|jquery)"

pyproject.toml

@@ -0,0 +1,20 @@
+[tool.ruff]
+src = ["flask_mail.py"]
+fix = true
+show-fixes = true
+output-format = "full"
+
+[tool.ruff.lint]
+select = [
+    "B",  # flake8-bugbear
+    "E",  # pycodestyle error
+    "F",  # pyflakes
+    "I",  # isort
+    "UP", # pyupgrade
+    "W",  # pycodestyle warning
+]
+ignore-init-module-imports = true
+
+[tool.ruff.lint.isort]
+force-single-line = true
+order-by-type = false

requirements/dev.in

@@ -1,2 +1,3 @@
 -r tests.txt
 tox
+pre-commit

requirements/dev.txt

@@ -6,6 +6,8 @@
 #
 cachetools==5.3.3
     # via tox
+cfgv==3.4.0
+    # via pre-commit
 chardet==5.2.0
     # via tox
 colorama==0.4.6
@@ -20,12 +22,16 @@ filelock==3.14.0
     # via
     #   tox
     #   virtualenv
+identify==2.5.36
+    # via pre-commit
 iniconfig==2.0.0
     # via
     #   -r tests.txt
     #   pytest
 mock==5.1.0
     # via -r tests.txt
+nodeenv==1.8.0
+    # via pre-commit
 packaging==24.0
     # via
     #   -r tests.txt
@@ -41,10 +47,14 @@ pluggy==1.5.0
     #   -r tests.txt
     #   pytest
     #   tox
+pre-commit==3.5.0
+    # via -r dev.in
 pyproject-api==1.6.1
     # via tox
 pytest==8.2.1
     # via -r tests.txt
+pyyaml==6.0.1
+    # via pre-commit
 speaklater==1.3
     # via -r tests.txt
 tomli==2.0.1
@@ -56,4 +66,9 @@ tomli==2.0.1
 tox==4.15.0
     # via -r dev.in
 virtualenv==20.26.2
-    # via tox
+    # via
+    #   pre-commit
+    #   tox
+
+# The following packages are considered to be unsafe in a requirements file:
+# setuptools

requirements/tests.in

@@ -1,3 +1,3 @@
 mock
 pytest
-speaklater
+speaklater

tox.ini

@@ -2,6 +2,7 @@
 envlist =
     py3{12,11,10,9,8}
     minimal
+    style
 skip_missing_interpreters = true
 
 [testenv]
@@ -17,6 +18,17 @@ commands = pytest -v --tb=short --basetemp={envtmpdir} tests.py
 deps =
 commands = python -c "from flask_mail import Mail"
 
+[testenv:style]
+deps = pre-commit
+skip_install = true
+commands = pre-commit run --all-files
+
+[testenv:update-pre_commit]
+labels = update
+deps = pre-commit
+skip_install = true
+commands = pre-commit autoupdate -j4
+
 [testenv:update-requirements]
 base_python = 3.8
 labels = update