Use pyupgrade, black, isort, and flake8 via pre-commit

6 files changed, 67 insertions, 30 deletions

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 35ea5eeb..e3cc7851 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,21 +7,6 @@ defaults:
     shell: bash
 
 jobs:
-  lint:
-    runs-on: ubuntu-latest
-
-    steps:
-      - name: Checkout Repository
-        uses: actions/checkout@v2
-      - name: Set up Python 3.8
-        uses: actions/setup-python@v2
-        with:
-          python-version: 3.8
-      - name: Install dependencies
-        run: python3.8 -m pip install nox
-      - name: Lint the code
-        run: nox -s lint
-
   package:
     runs-on: ubuntu-latest
 
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
new file mode 100644
index 00000000..055446cf
--- /dev/null
+++ b/.github/workflows/lint.yml
@@ -0,0 +1,21 @@
+name: lint
+
+on: [push, pull_request]
+
+jobs:
+  lint:
+    runs-on: ubuntu-20.04
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+      - name: Set up Python 3.8
+        uses: actions/setup-python@v2
+        with:
+          python-version: 3.8
+      - name: Lint the code
+        uses: pre-commit/action@v2.0.0
+      - name: Install dependencies
+        run: python3.8 -m pip install nox
+      - name: Run mypy
+        run: nox -s mypy
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 00000000..467b4831
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,23 @@
+repos:
+  - repo: https://github.com/asottile/pyupgrade
+    rev: v2.7.4
+    hooks:
+      - id: pyupgrade
+        args: ["--py36-plus"]
+
+  - repo: https://github.com/psf/black
+    rev: 20.8b1
+    hooks:
+      - id: black
+        args: ["--target-version", "py36"]
+
+  - repo: https://github.com/PyCQA/isort
+    rev: 5.6.4
+    hooks:
+      - id: isort
+
+  - repo: https://gitlab.com/pycqa/flake8
+    rev: 3.8.4
+    hooks:
+      - id: flake8
+        additional_dependencies: [flake8-2020]
diff --git a/noxfile.py b/noxfile.py
index ba0ec52c..4aa84a7d 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -86,23 +86,33 @@ def unsupported_python2(session):
 @nox.session()
 def format(session):
     """Run code formatters."""
-    session.install("black", "isort")
-    session.run("black", *SOURCE_FILES)
-    session.run("isort", *SOURCE_FILES)
+    session.install("pre-commit")
+    session.run("pre-commit", "--version")
 
-    lint(session)
+    process = subprocess.run(
+        ["pre-commit", "run", "--all-files"],
+        env=session.env,
+        text=True,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.STDOUT,
+    )
+    # Ensure that pre-commit itself ran successfully
+    assert process.returncode in (0, 1)
 
 
 @nox.session
 def lint(session):
-    session.install("flake8", "flake8-2020", "black", "isort", "mypy")
-    session.run("flake8", "--version")
-    session.run("black", "--version")
-    session.run("isort", "--version")
+    session.install("pre-commit")
+    session.run("pre-commit", "run", "--all-files")
+
+    mypy(session)
+
+
+@nox.session()
+def mypy(session):
+    """Run mypy."""
+    session.install("mypy")
     session.run("mypy", "--version")
-    session.run("black", "--check", *SOURCE_FILES)
-    session.run("isort", "--check", *SOURCE_FILES)
-    session.run("flake8", *SOURCE_FILES)
 
     session.log("mypy --strict src/urllib3")
     all_errors, errors = [], []
diff --git a/src/urllib3/request.py b/src/urllib3/request.py
index dc9e9e7d..9907d9ec 100644
--- a/src/urllib3/request.py
+++ b/src/urllib3/request.py
@@ -48,7 +48,7 @@ class RequestMethods:
         headers=None,
         encode_multipart=True,
         multipart_boundary=None,
-        **kw
+        **kw,
     ) -> BaseHTTPResponse:  # Abstract
         raise NotImplementedError(
             "Classes extending RequestMethods must implement "
@@ -107,7 +107,7 @@ class RequestMethods:
         headers=None,
         encode_multipart=True,
         multipart_boundary=None,
-        **urlopen_kw
+        **urlopen_kw,
     ) -> BaseHTTPResponse:
         """
         Make a request using :meth:`urlopen` with the ``fields`` encoded in
diff --git a/test/contrib/test_socks.py b/test/contrib/test_socks.py
index a068a621..693d8ec0 100644
--- a/test/contrib/test_socks.py
+++ b/test/contrib/test_socks.py
@@ -1,5 +1,3 @@
-from __future__ import absolute_import
-
 import socket
 import threading
 from socket import getaddrinfo as real_getaddrinfo