From 946502b6604564660562a7d0b6acaa54693a9c22 Mon Sep 17 00:00:00 2001
From: "Jason R. Coombs" <jaraco@jaraco.com>
Date: Sun, 30 Aug 2020 11:47:19 -0400
Subject: [PATCH 1/4] Add pre-commit hook definition for flake8.

---
 .pre-commit-config.yaml | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 .pre-commit-config.yaml

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 000000000..5a3900722
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,6 @@
+repos:
+-   repo: https://gitlab.com/pycqa/flake8
+    # TODO: update rev periodically to keep up with tox
+    rev: 3.8.3
+    hooks:
+    - id: flake8

From fd49047721fa61984cbe2e73bef042cdc3e672e8 Mon Sep 17 00:00:00 2001
From: "Jason R. Coombs" <jaraco@jaraco.com>
Date: Thu, 3 Sep 2020 18:48:16 -0400
Subject: [PATCH 2/4] Add news fragment.

---
 newsfragments/3398.minor | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 newsfragments/3398.minor

diff --git a/newsfragments/3398.minor b/newsfragments/3398.minor
new file mode 100644
index 000000000..477c141fd
--- /dev/null
+++ b/newsfragments/3398.minor
@@ -0,0 +1 @@
+Added pre-commit config to run flake8 checks on commit/push.

From ae1b0271df15b48e3c8923a05e296ca49e18217a Mon Sep 17 00:00:00 2001
From: "Jason R. Coombs" <jaraco@jaraco.com>
Date: Thu, 3 Sep 2020 18:59:46 -0400
Subject: [PATCH 3/4] Add new developer guide with instructions on using
 pre-commit.

---
 docs/developer-guide.rst | 44 ++++++++++++++++++++++++++++++++++++++++
 docs/index.rst           |  2 ++
 2 files changed, 46 insertions(+)
 create mode 100644 docs/developer-guide.rst

diff --git a/docs/developer-guide.rst b/docs/developer-guide.rst
new file mode 100644
index 000000000..15aa3cd8f
--- /dev/null
+++ b/docs/developer-guide.rst
@@ -0,0 +1,44 @@
+Developer Guide
+===============
+
+
+Pre-commit Checks
+-----------------
+
+This project is configured for use with `pre-commit <https://pre-commit.com>`_ to perform some static code analysis checks. By default, pre-commit behavior is disabled. To enable pre-commit in a local checkout, first install pre-commit (consider using `pipx <https://pipxproject.github.io/pipx/>`_), then install the hooks with ``pre-commit install``.
+
+For example::
+
+	tahoe-lafs $ pre-commit install
+	pre-commit installed at .git/hooks/pre-commit
+	tahoe-lafs $ echo "def foo():\n\t''" > src/allmydata/tabbed.py
+	tahoe-lafs $ git add src/allmydata/tabbed.py
+	tahoe-lafs $ git commit -a -m "Add a file that violates flake8"
+	flake8...................................................................Failed
+	- hook id: flake8
+	- exit code: 1
+
+	src/allmydata/tabbed.py:2:1: W191 indentation contains tabs
+
+To uninstall::
+
+	tahoe-lafs $ pre-commit uninstall
+	pre-commit uninstalled
+
+
+Some find running linters on every commit to be a nuisance. To avoid the checks triggering during commits, but to check before pushing to the CI, install the hook for pre-push instead::
+
+	tahoe-lafs $ pre-commit install -t pre-push
+	pre-commit installed at .git/hooks/pre-push
+	tahoe-lafs $ git commit -a -m "Add a file that violates flake8"
+	[3398.pre-commit 29f8f43d2] Add a file that violates flake8
+	 1 file changed, 2 insertions(+)
+	 create mode 100644 src/allmydata/tabbed.py
+	tahoe-lafs $ git push
+	flake8...................................................................Failed
+	- hook id: flake8
+	- exit code: 1
+
+	src/allmydata/tabbed.py:2:1: W191 indentation contains tabs
+
+	error: failed to push some refs to 'github.com:jaraco/tahoe-lafs.git'
diff --git a/docs/index.rst b/docs/index.rst
index 581e74bbb..3d0a41302 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -39,6 +39,8 @@ Contents:
    write_coordination
    backupdb
 
+   developer-guide
+
    anonymity-configuration
 
    nodekeys

From 1b412a6e9ff8fba1c338d2e513c1a296c14ba73d Mon Sep 17 00:00:00 2001
From: "Jason R. Coombs" <jaraco@jaraco.com>
Date: Fri, 11 Sep 2020 15:11:01 -0400
Subject: [PATCH 4/4] Use python rather than relying on shell-specific syntax.
 Tested on bash and xonsh on macOS.

---
 docs/developer-guide.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/developer-guide.rst b/docs/developer-guide.rst
index 15aa3cd8f..9b40bb283 100644
--- a/docs/developer-guide.rst
+++ b/docs/developer-guide.rst
@@ -11,7 +11,7 @@ For example::
 
 	tahoe-lafs $ pre-commit install
 	pre-commit installed at .git/hooks/pre-commit
-	tahoe-lafs $ echo "def foo():\n\t''" > src/allmydata/tabbed.py
+	tahoe-lafs $ python -c "import pathlib; pathlib.Path('src/allmydata/tabbed.py').write_text('def foo():\\n\\tpass\\n')"
 	tahoe-lafs $ git add src/allmydata/tabbed.py
 	tahoe-lafs $ git commit -a -m "Add a file that violates flake8"
 	flake8...................................................................Failed