Introduction to Cucumber

In behavior driven development, both developer and stakeholder can write automated test cases. Based on the documented test cases, stakeholder confirms the behavior that he is expecting from the application. Since these test cases are considered as acceptance criteria to release a product/application, these are termed as acceptance tests.

How acceptance tests are different from unit tests?

Unit tests are completely driven by the developer to make sure everything is working fine. Whereas acceptance tests are documented by developer and stakeholders to make sure that you are building the right thing.

a.   Domain experts may not be technical and technical experts may not have complete domain knowledge. So, we need a way to establish proper communication between domain expert and technical user.

b.   The requirements provided by the domain expert can be in abstract form. It is difficult to the technical user to understand.

Why Cucumber?

Cucumber fills the gap between developers and stake holders. By using cucumber, all the stakeholders can be involved in writing test cases. Test cases are written in general (like English, French etc.,) language, that is understandable by stakeholders. These test cases are mapped to the actual test code developed by technical users.

Better communication should be established between stake holders and developers to get rid of misunderstandings.

Stakeholders/developers write the acceptance test cases in .feature file. A feature file is a collection of scenarios, where each scenario targets an independent use case.

Login.feature

Feature: Login

 Login should be quick and friendly.
 
 Scenario: Successful Login
  Users should be logged in successfully by providing correct username and password.
  
  Given I have chosen to Login
  When I log in with correct user name and password
  Then I should be logged in successfully
  And I should see a personalized greeting message
  
  
 Scenario: Login failed with wrong user name and correct password
 
  User log in should fail on wrong user name
 
 
  Given I have chosen to Login
  When I log in with wrong user name and correct password
  Then I should not be logged in
  And I should see an error message
  
 Scenario: Login failed with correct user name and wrong password
 
  User log in should fail on wrong password
 
 
  Given I have chosen to Login
  When I log in with correct user name and wrong password
  Then I should not be logged in
  And I should see an error message

As you see, Login.feature contains the test scenarios to be tested against login module of the application. The statements in the ‘.feature’ file are written using Gherkin rules. For example, Feature, Scenario, Given, When, Then, And are the terms in Gherkin language. Cucumber process these terms separately.

How cucumber works?

a.   Stakeholders write the scenarios in a feature file.

b.   When you ran cucumber, it reads the feature file and parse the scenarios to test.

c.   After parsing the scenarios, it runs each scenario against the application.

Note

Scenario is a collection of steps

Feature is a collection of scenarios

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