Add pre commit

.devcontainer/Dockerfile

@@ -1,7 +1,7 @@
 # See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.209.5/containers/python-3/.devcontainer/base.Dockerfile
 
 # [Choice] Python version (use -bullseye variants on local arm64/Apple Silicon): 3, 3.10, 3.9, 3.8, 3.7, 3.6, 3-bullseye, 3.10-bullseye, 3.9-bullseye, 3.8-bullseye, 3.7-bullseye, 3.6-bullseye, 3-buster, 3.10-buster, 3.9-buster, 3.8-buster, 3.7-buster, 3.6-buster
-ARG VARIANT="3.10-bullseye"
+ARG VARIANT="3.8-bullseye"
 FROM mcr.microsoft.com/vscode/devcontainers/python:0-${VARIANT}
 
 # [Choice] Node.js version: none, lts/*, 16, 14, 12, 10

.devcontainer/devcontainer.json

@@ -9,7 +9,7 @@
 			// Update 'VARIANT' to pick a Python version: 3, 3.10, 3.9, 3.8, 3.7, 3.6
 			// Append -bullseye or -buster to pin to an OS version.
 			// Use -bullseye variants on local on arm64/Apple Silicon.
-			"VARIANT": "3.9-bullseye",
+			"VARIANT": "3.8-bullseye",
 			// Options
 			"NODE_VERSION": "lts/*"
 		}

.github/workflows/ci.yml

@@ -10,6 +10,16 @@ on:
     branches: [ master ]
 
 jobs:
+  style:
+    name: Code linting checks
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: psf/black@stable
+        with:
+          options: "--check --verbose"
+          version: "22.1.0"
+
   build:
     name: build (${{ matrix.os }}, ${{ matrix.python-version }})
     runs-on: ${{ matrix.os }}

.pre-commit-config.yaml

@@ -0,0 +1,8 @@
+# See https://pre-commit.com for more information
+# See https://pre-commit.com/hooks.html for more hooks
+repos:
+  - repo: https://github.com/psf/black
+    rev: 22.1.0
+    hooks:
+      - id: black
+        language_version: python3.8

gsw_xarray/tests/test_units.py

@@ -29,6 +29,7 @@ def test_unit_pint(func_name):
         print(a["units"])
         ureg.Unit(a["units"])
 
+
 @pytest.mark.parametrize("func_name", gsw_base)
 def test_unit_cf_units(func_name):
     cf_units = pytest.importorskip("cf_units")

pyproject.toml

@@ -15,6 +15,7 @@ furo = {version = ">=2022.1.2", optional = true}
 [tool.poetry.dev-dependencies]
 pytest = ">=6.2.5"
 Pint = ">=0.18"
+pre-commit = "^2.17.0"
 
 [tool.poetry.extras]
 docs = ["Sphinx", "furo"]