BDD Workshop

workshop.md

BDD Workshop

Steps

• install ruby 1.9.3-p551
• update rubygems with gem update --system
• install gems bundle install --without staging:production

Activities

• convert rspec feature tests to cucumber features

Converting to cucumber

• Write feature

• Write scenario

• Run feature

• Steps will be skipped

• Read the output, giving hints on how to write steps

• Write steps

• Repeat

Notes

BDD comes from TDD, which comes from XP. The idea of acceptance test (from XP) is that the developers and the stakeholders collaborate to write tests that describe the outcome that the stakeholder wants.

Acceptance tests help you build the right thing, unit tests to build the thing right

BDD formalizes TDD best practices, like:

• Outside-in testing: starting from the customer's perspective
• Focus on user stories, using concrete examples
• Focus on ubiquitous language (Gherkin)

Advantages of BDD

• The Cucumber features become a "living documentation" (they don't go out of date after having been written), and the source of truth.

• The code you write will be the minimum necessary to satisfy the required features.

• You will have a clear overview of what you want to do, before you start doing it.

How to write a step

• Learn regular expressions:
  • groups, non-capturing groups
  • character classes: [0-9], [a-z], [A-Z]
  • shorthand classes: \d, \w, \s, \b
  • modifiers: *, +, ?
  • anchors: ^, $
• Groups create block variables
• Use pending when you're still working on the step

Best practices

• Re-use steps. Cucumber will require all ruby files under the features directory, which means you can use steps defined in any file from any feature.
• Use plain ruby modules and methods to group together invocations to Capybara's helpers. This is much better than nesting steps.

        module LoginSteps
          def login(name, password)
            visit('/login')
            fill_in('User name', with: name)
            fill_in('Password',  with: password)
            click_button('Log in')
          end
        end

    World(LoginSteps)

• Keep your steps discursive, declarative and high-level. Avoid implementation details.

  Bad:

    Scenario: Successful login
      Given a user "Aslak" with password "xyz"
      And I am on the login page
      And I fill in "User name" with "Aslak"
      And I fill in "Password" with "xyz"
      When I press "Log in"
      Then I should see "Welcome, Aslak"
  

  Good:

    Scenario: Successful login
      Given the user "Aslak" has an account
      When he logs in
      Then he should see "Welcome, Aslak"
  

• Split your features and step definitions in subdirectories.

• Use @tags

Links

Cucumber

• https://github.com/cucumber/cucumber/wiki/Cucumber-Backgrounder

JavaScript

• https://github.com/modeset/teaspoon/wiki/Quick-Start-Walkthrough