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Waterpig

A collection of helpers for Rails integration testing with Capybara, RSpec, RSpec-Steps, and DatabaseCleaner collected over several years by Logical Reality Design.

Selecting A Browser Driver

You can set JS and non-JS capybara drivers with either environment variables or your rspec config. The two currently supported drivers are poltergeist_debug (Poltergeist with remote debugging enabled) and selenium_chrome. If none is specified, waterpig will try to configure poltergeist_debug by default.

Mostly one cares about drivers when :js => true in capybara specs, in which case capybara_js_driver is the setting you care about.

At the command line:

CAPYBARA_JS_DRIVER=poltergeist_debug rspec spec/features/my_cool_spec.rb
CAPYBARA_JS_DRIVER=selenium_chrome rspec spec/features/my_cool_spec.rb

In your rspec config

RSpec.configure do |config|
  config.capybara_js_driver = :selenium_chrome
end

Browser Snapshotting

If you are also using the rspec-steps gem and poltergeist, Waterpig's Autosnap feature can generate screenshots of the browser at the beginning of each step, to give you intelligence on the test in the middle of a user story. To use it simply set the environment variable WATERPIG_AUTOSNAP, for example:

WATERPIG_AUTOSNAP=true rspec spec/features/my_cool_spec.rb

Or set config.waterpig_autosnap? to true in your RSpec config.

Screenshots will be emitted into tmp/, with a subdirectory named for each spec and a numbered file for each step.

Browser Console Logging

The Waterpig::BrowserConsoleLogger class can execute a remote call to console.history() in your browser to retrieve the contents of the browser console, and log it to file. This is extremely useful for debugging front-end issues during integration specs.

For browser console logging to work, the console.history() method must have already been defined in your browser. This must be handled separately, see the console history injector in Xing for an example.

To turn on browser console logging:

At the command line:

LOG_BROWSER_CONSOLE=true rspec spec/features/my_cool_spec.rb

In your rspec config

RSpec.configure do |config|
  config.waterpig_log_browser_console = true
end

Database Cleaning

Because database cleaning is sich a tricky problem, Waterpig tries to handle it in the best way possible. There are several configuration knobs to adjust if needed.

However, nota bene: you must set

RSpec.configure do |config|
  config.use_transaction_fixtures = false
end

or you'll have a bad time.

Transactions

Most test types, Waterpig leans on rspec-rails's transactional fixtures, so there's a BEGIN at the beginning of a test and ROLLBACK at the end. This is almost always what you want - it's fast and correct.

Resets

For feature specs (i.e. when you're pointing Capybara at a test server) and other kinds of tests, transactional fixtures doesn't do the job: the test server and the test itself run in different threads, so they have different connections to the database and therefore don't see "inside" each other's transactions. If you try to change the database using browser actions and then check the database in the tests, you're going to have a (mysteriously) bad time.

To cope with this case, as well as situations where you really do want to test whole-database changes, Waterpig provides tools to "reset" the database to a pristine state.

The first thing to know is how to turn on resets for a set of tests. The easiest is to hook into RSpec's existing metadata. Most spec groups are marked with a :type field (it used to be automatic, but there remain features of rspec-rails that depend on the type of the tests)

Simply add this to your RSpec.configuration block (in e.g. spec_helper.rb)

config.waterpig_reset_types = [:feature]

That's actually the default, so in most projects you won't even have to change anything.

Waterpig actually uses one of two methods to do DB resets, "truncation" or "refresh." They each have their tradeoffs, so it's worth discussing them.

Truncation

The simplest cleaning strategy is this: truncate all the tables in the database between tests. It's okay for speed, but the real hangup is when you've got a complex seeds.rb - if, for instance, you need to ingest a ZIP code database. Apart from being slow, truncation is really reliable

Refresh

If you're using PostgreSQL, Waterpig has an alternative method for doing resets that can bemuch faster called "refresh." You need to configure a new ActiveRecord database configuration, exactly like your existing :test config, called :test_template. It needs its own database name. Then add the name of the :test_template database to your :test config under a key called template. In the end, the things you've added to database.yml should look something like:

test:
  adapter: postgresql
  database: my_app_test
  template: my_app_test_template

test_template:
  adapter: postgresql
  database: my_app_test_template

Then, in spec_helper.rb add:

RSpec.configure do |config|
  config.waterpig_reset_method = :refresh
end

Here's how reset works: Waterpig will make sure that the test_template database exists, and if it needs to be migrated then it will be migrated and seeded. Then, before tests that need to be reset it'll drop the test database and recreate it, using test_template as the PostgreSQL template database - the schema and data from a migrated and seeded database. This happens very quickly.

One big warning here: Waterpig will create test_template if it's missing or recreate it if its migrations are behind, but not if it isn't up to date on db/seeds.rb. If you change seeds, you'll need to

> RAILS_ENV=test_template bundle exec rake db:drop

or your specs will fail mysteriously. It's this shortcoming that prevents us making :refresh the default reset method.

Or, you can add a this to lib/tasks/databases.rb (possibly a new file) in your Rails project:

namespace :db do
  task :seed do
    ActiveRecord::DatabaseTasks.drop_current(:test_template)
    ActiveRecord::DatabaseTasks.create_current(:test_template)
  end
end

If you need to change the database config names, you can:

RSpec.configure do |config|
  config.waterpig_test_database_config = :just_checking
  config.waterpig_test_template_database_config = :just_checking_like_this
end

Do What I Say

If you need to set up tests so that they don't get cleaned, you can put their type into config.waterpig_skip_cleaning_types which is an Array.

If you want to force a single example or group of examples not to be cleaned, you can do like:

RSpec.describe "these tests should not be cleaned", :manual_database_cleaning do
  #...
end

If you want to force a particular cleaning method:

RSpec.describe "these tests have weird requirements", :clean_with => :reset do
  #...
end

The metadata keys above are configurable at config.waterpig_exclude_cleaning_key and config.waterpig_explicit_cleaning_method_key

Config Reference

Config Name | Purpose | Values | Default Value ---: | :---- | :---- config.waterpig_exclude_cleaning_key | The name of the metadata key to mark test that should not be cleaned | Boolean | :manual_database_cleaning config.waterpig_explicit_cleaning_method_key | The name of the metadata key to force a particular cleaning method | :reset, :refresh, :truncate, :transaction, :dont_clean | :clean_with config.waterpig_database_reset_method | How "reset" cleaning is performed | :refresh, :truncate | :truncation config.waterpig_reset_types | RSpec test types that should be reset (truncated or refreshed) | Array | [:feature] config.waterpig_skip_cleaning_types | RSpec test types that shouldn't be cleaned | Array | [] config.waterpig_exclude_seeds_types | RSpec test types where db seeds shouldn't be loaded after truncating | Array | [] config.waterpig_truncation_types | RSpec test types that should be truncated (deprecated, prefer waterpig_reset_types) | Array | [:feature] config.waterpig_database_truncation_config | DatabaseCleaner configuration for truncating | Hash | {:except => %w[spatial_ref_sys]} config.waterpig_db_seeds | Path to the db_seeds file to use when truncating | String | 'db/seeds.rb' config.waterpig_test_database_config | The name of the test database config for refreshing | Symbol | :test config.waterpig_test_template_database_config | The name of the template test database config for refreshing | Symbol | :test_template

Experimental Features

These are features of Waterpig that are being used in real projects, but for which the interfaces in Waterpig haven't been designed yet.

Mobile browser emulation

Currently in bleeding edge beta are registered drivers for Capybara: mobile_chrome_ios and mobile_chrome_android. Try them against your codebase with

CAPYBARA_DRIVER=mobile_chrome_android CAPYBARA_JS_DRIVER=mobile_chrome_android rspec spec

Blocking Spec Cleanup For Browser Requests

Much suffering is caused when rspec and Capybara clean up after a spec while a request is still being processed. Typically, the database fixtures are reset by DatabaseCleaner because rspec thinks the example is complete, but then something fails in Rails when an expected database record is absent. This can cause mysterious intermittant, timing-related failures in specs.

To fix this, install RequestWaitMiddleware as a middleware and configure your end-to-end tests to block on Waterpig::RequestWaitMiddleware.wait_for_idle(), as follows:

In config/environments/test.rb

Rails.application.configure do
  config.middleware.unshift Waterpig::RequestWaitMiddleware
end

In your rspec config, wrap your (e.g.) database cleanup command in a call to wait_for_idle(). Assuming all your end-to-end tests have the metadata :type => :feature, you could:

RSpec.configure do |config|

  config.before(:all, :type => :feature) do
    Waterpig::RequestWaitMiddleware.wait_for_idle do
      DatabaseCleaner.clean(:truncation)
    end
  end
end