NdrDevSupport Maintainability Build Status Gem Version

This is the NHS Digital (NHS-D) National Disease Registration Service (NDRS) Developer Support ruby gem, providing:

  1. rake tasks to manage code auditing of ruby based projects
  2. rake tasks to limit Rubocop's output to changed (and related) code
  3. integration testing support, which can be required from a project's test_helper.rb
  4. Deployment support, through Capistrano.
  5. a rake task based Continuous Integration (CI) server.


Add this line to your application's Gemfile:

gem 'ndr_dev_support', group: [:development, :test]

And then execute:

$ bundle

Or install it yourself as:

$ gem install ndr_dev_support

To add development support tasks (see below) to your project, add this line to your application's Rakefile:

require 'ndr_dev_support/tasks' if Rails.env.development? || Rails.env.test?


Code Auditing Rake Tasks

ndr_dev_support provides a mechanism to manage the state of routine code quality and security peer reviews. It should be used as part of wider quality and security policies.

It provides rake tasks to help manage the process of persisting the state of security reviews.

Once files have been reviewed as secure, the revision number for that file is stored in code_safety.yml. If used within a Rails app, this file is stored in the config/ folder, otherwise it is kept in the project's root folder.

Note: This feature works with svn and git repositories and svn, git-svn and git working copies.

For more details of the audit tasks available, execute:

$ rake -T audit

RuboCop configuration

ndr_dev_support includes tweaks to the default Ruby and Ruby on Rails Style Guides, to better suit NDR. To use these updated style guides from within a project, add the following to top of the project's .rubocop.yml file:

require: ndr_dev_support

Or, if using other extensions too:

  - ndr_dev_support
  - some_other_extension

In order for these configurations to apply, you will need to invoke RuboCop using Bundler:

$ bundle exec rubocop .

...or use the bundled rake task (see next section).

RuboCop filtering

ndr_dev_support also provides rake tasks to enable more targeted use of RuboCop, to analyse only relevant code changes:

$ rake rubocop:diff HEAD
$ rake rubocop:diff HEAD~3..HEAD~2
$ rake rubocop:diff HEAD~3..HEAD~2
$ rake rubocop:diff aef12fd4
$ rake rubocop:diff master
$ rake rubocop:diff path/to/file
$ rake rubocop:diff dir/

As well as the primary rubocop:diff task, there are a number of convenience tasks provided:

$ rake rubocop:diff:head
$ rake rubocop:diff:staged
$ rake rubocop:diff:unstaged
$ find . -iregex .*\.rake$ | xargs rake rubocop:diff:file

Integration test environment

ndr_dev_support bundles a configured Rails integration testing environment.

By default, it uses capybara and selenium to drive a headless Chrome browser, and includes some sensible configuration.

To use, simply add the following to your application's test_helper.rb

require 'ndr_dev_support/integration_testing'

Other drivers

Other drivers are also supported; chrome / chrome_headless / chrome_headless_old / firefox are all powered by selenium, and can either be explicitly used with:

Capybara.default_driver    = :chrome_headless
Capybara.javascript_driver = :chrome_headless

...or, assuming no driver has been explicitly set, can be selected at runtime:

$ INTEGRATION_DRIVER=chrome_headless bin/rake test


If an integration test errors or fails, capybara-screenshot is used to automatically retrieve a full-height screenshot from the headless browser, which is then stored in tmp/.

DSL extensions

Beyond standard Capybara testing DSL, ndr_dev_support bundles some additional functionality:

  • clear_headless_session! - causes the headless browser to reset, simulating a browser restart.
  • delete_all_cookies! - causes the headless browser to delete all cookies. Helpful for testing AJAX logouts.
  • within_screenshot_compatible_window – similar to within_window, but allows failure screenshots to be taken of the failing child window, rather than the spawning parent.
  • within_modal - scope capybara to only interact within a modal, and (by default) expect the modal to disappear when done.

Database synchronisation

When using a headless browser for integration tests, the test database must be consistent between the test runner and the application being tested. With transactional tests in operation, this means that both must share a connection. It is up to the individual project to provide this facility; as of Rails 5.1, it is built in to the framework directly.

Flakey Tests

It is an unfortunate reality that sometimes tests are written that will fail sporadically. Whilst in such cases the test methodology should be addressed, investigations can be time-consuming. Therefore, ndr_dev_support grudgingly provides "flakey test" support, to minimise disruption to CI pipelines whilst root causes are investigated.

test 'thing that always passes' do
  # reliable test

flakey_test 'thing that occassionally needs a second or third attempt' do
  # less reliable test

flakey_test 'thing that often needs multiple attempts', attempts: 10 do
  # really unreliable test (gulp...)

If tests still fail, they'll fail as normal. If tests pass after flakey failure, they'll be flagged to the RakeCI server, and rendered in purple on Slack.

Repeating Flakey Tests

To aid with investigations into potentially-flakey tests, ndr_dev_support also provides the ability to run an integration test repeatedly (by default, 100 times):

test_repeatedly 'thing that we think might fail' do
  # something flakey

test_repeatedly 'thing that we think might fail very occassionally', times: 1000 do
  # something slightly flakey

This may be faster to work with than repeatedly executing the entire test runner in a bash loop, for example.

Deployment support

There are various capistrano plugins in the ndr_dev_support/capistrano directory - see each one for details. For new projects, you should likely add the following:

# in config/deploy.rb
require 'ndr_dev_support/capistrano/ndr_model'

This will pull in the majority of behaviour needed to deploy in our preferred style.

Rake CI server

ndr_dev_support provides a rake based continuous integration server that runs on a git or git svn working copy of your application. It polls for changes to the respository and, unlike some CI servers, it checks out and tests every commit; enabling full and comparative analysis of code quality and other statistical trends.

Out of the box it does nothing, but does provide a number of rake tasks that you can opt to use. Those rake tasks utilise the concepts of metrics and attachments (messages) and tasks tend to either generate them or publish them.

NOTE: As the way tests are run across applications differs, the :default rake task must be able to run your full suite of tests.

CI rake tasks have been written for:

  • ci:brakeman - brakeman vulnerability scanner metrics are generated for warning counts and "danger" messages for new warnings and "good" messages for fixed warnings.
  • ci:bundle_audit - generates "danger" messages for high criticality bundle audit advisories and "warning" messages for all others.
  • ci:commit_cop - Runs a number of commit "Cops" which create messages when common commit mistakes occur. Current cops look for a Rails migration added without a structure dump file, modified Rails migrations and renamed Rails migrations.
  • ci:dependencies:process - generates a line of pipe delimited markup showing system dependencies (that could be used in a wiki page on Redmine)
  • ci:housekeep - runs rake log:clear and rake tmp:clear if defined
  • ci:linguist - generates project programming language metrics for languages over 1% of codebase.
  • ci:minitest - sets up Minitest and SimpleCov to capture metrics and messages and runs the default rake task and ci:simplecov:process before running ci:redmine:update_tickets if all tests pass.
  • ci:notes - runs the Rails rake notes task (if using Rails) and converts annotation counts into metrics.
  • ci:prometheus:publish - sends all metrics to specified Prometheus push gateway.
  • ci:redmine:update_tickets - if all tests pass, this will parse the commit message and resolve associated Redmine tickets.
  • ci:rugged:commit_details - if there are messages, then it prepends message list with commit details.
  • ci:simplecov:process - generates metrics for SimpleCov measured test covered lines, test coverage percentage and total lines of code.
  • ci:slack:publish - sends all messages to specified Slack channel.
  • ci:stats - runs the Rails rake stats task (if using Rails) and converts counts into metrics

To start the server, cd to the working copy and execute:

$ rake ci:server

Configuration is managed within your application by implementing the ci:all rake task. When a new commit is detected, it checks it out and runs rake ci:all.

An example Rails application rake task might look like:

namespace :ci do
  desc 'Setup CI stack, integrations, etc up front'
  task setup: [

  desc 'all'
  task all: [
    # Setup
    # Test and Analyse
    # Report

NOTE: Defining the ci:setup rake tasks up front is not necessary, but will prompt for missing server credentials at the start of the first CI run.


After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.


Bug reports and pull requests are welcome on GitHub at https://github.com/NHSDigital/ndr_dev_support. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

  1. Fork it ( https://github.com/NHSDigital/ndr_dev_support/fork )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request


The gem is available as open source under the terms of the MIT License.