Selenium Cucumber Docker

This repo provides a simple way to setup a Ruby/Cucumber/Capybara/Selenium-Chrome based BDD environment.

See support/env.rb for the magic.

Quick start (tl;dr)

Open a terminal in root directory and follow these steps:

# Use docker compose to start start the two services
# and open a bash session in the 'ruby' service:

docker-compose run ruby bash
# Note: This could take a few min the first time you run...

# To see the browser, connect to the second container via VNC 
# The password is 'secret'.
# From the Finder: Go > Connect to server (cmd+k)

# You can also open a NEW terminal session and run this command:
open vnc://:[email protected]:5900

# Back in the original terminal session, we're now inside our ruby service.
# Run the tests with cucumber
cucumber

# When you're done, you can exit the ruby container
exit

# Now (from the host machine) stop all the containers
docker-compose down

Background

The basic components of BDD are:

• A running application to test (usually a web app)
• A web browser (like Chrome) to render the app and give access to the UI elements
• A web driver (like Selenium) to drive the browser
• A testing framework (like Capybara) to examine (and interact with) elements on the page
• A BDD framework (like Cucumber) to describe our tests (using Gherkin syntax), run them for us, and report on the results.
• Some language to define the step definitions and tie everything together (in this case, Ruby)

Using Docker

Docker compose makes it easy to package all the components into a couple of simple services (containers) and mount your source code into the containers from the host, without installing anything locally.

• The first service (which we'll call 'ruby') will hold the ruby runtime and any gems we need (e.g. cucumber and capybara). We'll build this with our Dockerfile.
• The second service will be an instance of the stand-alone Selenium-Chrome container.

Seeing the browser

Because the standalone-chrome-debug Chrome container gives you a full Ubuntu environment, you can view (and interact with) the running browser via VNC. This is helpful for debugging and writing new tests.

TROUBLESHOOTING

Getting an error that port 5900 is already allocated.

You may have "Screen sharing" enabled on your mac. Go to "Settings" > "Sharing" and untick the "Screen Sharing box"

Advanced usage

Run tests in one step

docker-compose run ruby cucumber

Using the 'pry' debugger.

You can add a step And I debug to your features to open the pry interactive debugger which lets you write code to interact with the browser in real-time without restarting your tests.

Go headless

If you don't need to see the browser, you can use a smaller/faster headless Selenium container:

docker run -d -p 4444:4444 -p 5900:5900 selenium/standalone-chrome

Manually start a browser session

You can manually start a browser session in the Selenium container:

• Browse to http://0.0.0.0:4444/wd/hub
• Click "Create session"
• Select "Chrome"
• Connect via VNC (see above) open vnc://:[email protected]:5900

Use Scenario Outlines

You can use "scenario outlines" to quickly run through the same scenario with different variables.