Acceptance test in elixir

Acceptance tests help ensure that applications we develop are deployed with minimal bugs. Manual acceptance testing is extremely valuable, but it can also be tedious and time-consuming. At DF, we've applied the automation End2End testing for our development process. In End2End test, we can open the web page, navigate on the web like a real user. In elixir project, we can do the same thing with Hound and a WebDriver.

The WebDriver is an interface to automate browsers. We can use WebDriver implementation to build an automated test suite against a real browser.

Hound is an Elixir library to write WebDriver. Writing End2End test with Hound is very similar to writing a normal ExUnit test. An advantage to writing automation tests is the same code base.

Common Web Drivers

https://github.com/HashNuke/hound/wiki/Starting-a-webdriver-server

Selenium

$ brew install selenium-server-standalone

ChromeDriver server

$ brew install --cask chromedriver

Run command:

$ chromedriver

PhantomJS web driver

$ brew cask install phantomjs

Run command:

$ phantomjs --wd

Configure Hound

Add dependency to mix.exs:

{:hound, "~> 1.0"}

Follow the setup step in https://hexdocs.pm/phoenix_ecto/Phoenix.Ecto.SQL.Sandbox.html:

• add the plug to Endpoint
• update the config/test.exs to run real server when execute test cases
• add the hound config in config/test.exs. We can update the config for other driver and browser config.

config :hound, driver: "chrome_driver", browser: "chrome_headless"

• Update test/test_helper.ex. We must start :hound application before run the unit test.

Application.ensure_all_started(:hound)

Make an unit test

As any unit test we need a module to store the test cases. We implement the setup func for Web driver initial Hound.Helpers provides the functions to control the browser easier. We can navigate, inspect html element, make the click action via this package. Use assert to validate the result

defmodule Acceptance.HomePageTest do
    use ExUnit.Case, async: false
    use Hound.Helpers

    setup do
        Hound.start_session()
        :ok
    end

    test "the page loads" do
        navigate_to("http://localhost:4002")
        assert page_title() == "Homepage"
    end
end

Note

Before run test we MUST start the web driver first https://hexdocs.pm/hound/Hound.Helpers.Navigation.html