From a51631c3064370545318800c2554dc8040a02364 Mon Sep 17 00:00:00 2001
From: Thibaud Colas <thibaudcolas@gmail.com>
Date: Tue, 23 Apr 2019 12:58:58 +0100
Subject: [PATCH] Add jinjalint linter for Django templates, allowing errors
 for now

---
 .circleci/config.yml                  |  1 +
 Makefile                              |  1 +
 docs/contributing/html_guidelines.rst | 16 ++++++++++++++++
 docs/contributing/index.rst           |  1 +
 setup.py                              |  3 +++
 5 files changed, 22 insertions(+)
 create mode 100644 docs/contributing/html_guidelines.rst

diff --git a/.circleci/config.yml b/.circleci/config.yml
index 3f2ed2b266..e4317cd5ec 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -17,6 +17,7 @@ jobs:
           key: pip-package-v1-{{ .Branch }}
       - run: pipenv run flake8 wagtail
       - run: pipenv run isort --check-only --diff --recursive wagtail
+      - run: pipenv run jinjalint --parse-only wagtail || true
       - run: DATABASE_NAME=wagtail.db pipenv run python -u runtests.py
 
   frontend:
diff --git a/Makefile b/Makefile
index 4ffa2dfb85..baf49884a2 100644
--- a/Makefile
+++ b/Makefile
@@ -18,6 +18,7 @@ develop: clean-pyc
 lint:
 	flake8 wagtail
 	isort --check-only --diff --recursive wagtail
+	jinjalint --parse-only wagtail || true
 	npm run lint:css --silent
 	npm run lint:js --silent
 
diff --git a/docs/contributing/html_guidelines.rst b/docs/contributing/html_guidelines.rst
new file mode 100644
index 0000000000..c6640b75f2
--- /dev/null
+++ b/docs/contributing/html_guidelines.rst
@@ -0,0 +1,16 @@
+HTML coding guidelines
+======================
+
+We use `Django templates <https://docs.djangoproject.com/en/stable/ref/templates/language/>`_ to author HTML.
+
+Linting HTML
+~~~~~~~~~~~~
+
+We use `jinjalint <https://github.com/motet-a/jinjalint>`_ to lint templates. If you have installed Wagtail's testing dependencies (``pip install -e .[testing]``), you can check your code by running ``make lint``.
+
+Principles
+~~~~~~~~~~
+
+* Write `valid HTML <https://validator.w3.org/nu/>`_. We target the HTML5 doctype.
+* Attach JavaScript behavior with ``data-`` attributes, rather than classes or IDs.
+* For comments, use Django templates syntax instead of HTML.
diff --git a/docs/contributing/index.rst b/docs/contributing/index.rst
index 26af9ac2f3..8ad4bf1fb6 100644
--- a/docs/contributing/index.rst
+++ b/docs/contributing/index.rst
@@ -60,6 +60,7 @@ More information
     styleguide
     general_guidelines
     python_guidelines
+    html_guidelines
     css_guidelines
     javascript_guidelines
     release_process
diff --git a/setup.py b/setup.py
index 843bca4294..3a4113c2c2 100755
--- a/setup.py
+++ b/setup.py
@@ -53,6 +53,9 @@ testing_extras = [
     'isort==4.2.5',
     'flake8-blind-except==0.1.1',
     'flake8-print==2.0.2',
+
+    # For templates linting
+    'jinjalint>=0.5',
 ]
 
 # Documentation dependencies