GOV.UK Frontend (Jinja)

This Python package includes classes and modules to make it easier to use the GOV.UK Frontend in your Jinja2-powered Python web app.

NOTE: This repository is maintained by GDS developers, but not the GOV.UK Design System team. If you have questions or need support raise an issue against this repo here.

Installing

pip install git+https://github.com/Crown-Commercial-Service//govuk-frontend-jinja.git

Using with Flask

Somewhere in your app.py (or wherever you do your app initialisation):

import jinja2
from govuk_frontend_jinja.flask_ext import init_govuk_frontend

app.jinja_loader = jinja2.FileSystemLoader((
    "templates",
    "node_modules/govuk-frontend",  # path to govuk-frontend package
))

init_govuk_frontend(app)

Developing

This repo uses tox for testing; if you are hacking on the code all you need to do to test things out is run tox at the command line.

If for some reason you need a virtualenv with govuk_frontend_jinja installed you can run tox --devenv venv which will create venv for you (requires a recent version of tox).

Adding Tests

govuk_frontend_jinja should match the output of using Nunjucks with GOV.UK Frontend as much as possible.

The GOV.UK Design System hosts a website with examples for all components that can be used to get tests fixtures at govuk-frontend-review.

Tests for individual components should go in a file named tests/components/<component_name>/test_<component_name>.py. For instance:

# tests for accordion component
tests/
└── components/
    └── accordion/
        └── test_accordion.py

To aid in copying tests from govuk-frontend the test suite has support for fixture files that follow a set naming scheme. Files containing a template should be named test_<component_name>_<test_name>.t.html. Files containing the expected output of the template engine should be named test_<component_name>_<test_name>.x.html.

For example, for a test of the accordion component with one section open, the test suite expects the following structure of files and folders:

# tests for accordion component with fixture files
tests/
└── components/
    └── accordion/
        ├── test_accordion.py
        ├── test_accordion_with_one_section_open.t.html
        └── test_accordion_with_one_section_open.x.html

To use the fixture files a test must be written that reads and processes them. There are two pytest fixtures in our test suite called template and expected that simplify this. To use these, the test function must have the same name as the fixture file; returning to our example:

# test_accordion.py
def test_accordion_with_one_section_open(env, template, expected, similar):
    template = env.from_string(template)
    assert similar(template.render(), expected)

Autogenerating the pytest test function based on the fixture files so you don't need to write it yourself is planned as a future feature.

Credits

The initial code for this tool was based on work by HMLR, particularly @andymantell 🏆

All of the HTML and templates that this tool works on were produced by the GOV.UK Design System 🏅

And of course, none of this would be possible without Nunjucks and Jinja 🥂

Licence

Unless stated otherwise, the codebase is released under the MIT License. This covers both the codebase and any sample code in the documentation.

The documentation is © Crown copyright and available under the terms of the Open Government 3.0 licence.