Month: December 2015

Ashutosh Tiwari

BDD with Cucumber-JVM

Express the behavior of system

Cucumber-jvm is an open source BDD tool that lets user express the behavior of system under test in plain language like English, French, German etc. It is a great way to have an executable documentation of your system.

Required Maven Dependencies

Picture1


info.cukes
cucumber-picocontainer
${cucumber.version}


info.cukes
cucumber-junit
${cucumber.version}

Gherkin Keywords

Gherkin is the language that Cucumber understands.Gherkin is primarily used to write structured tests which can later be used as project documentation. The property of being structured gives us the ability to automate them.

Scenarios – Given When Then

We can define scenarios in given, when and then format.

Example-

Given a customer added one Item in shopping cart.
When the customer adds same Item in shopping cart.
Then the customer should be warned that same item is already in yours shopping cart.

Writing Scenario’s in Cucumber

• Scenarios are organized together into features.
• Each feature is represented as a plain text file.
• Feature files must have the “.feature” extension.
• Each feature can contain many scenarios.

Step Definitions

• A single Method representing a Step from a Feature file.
• The Method is annotated with information about the step it represents.
• Cucumber generates “Code Snippet’s” for Step Definition it can’t find.

Step Annotations

import cucumber.annotation.en.*;

Each Gherkin step keyword has a Annotation.


@When("^we want to stop traffic$")
public void methodName() { 
   ..........
}

Passing and Failing

Each step has it own result state.
– Passed
– Pending
– Skipped
– Failed
Individual step result state combined determine the Scenarios success or failure.
Steps can be failed on exceptions  or JUnit Assertion failures.

Regex Lesson

Cucumber uses Regular Expressions to match steps to definitions.

@When("^we want to stop traffic$")

^   Matches the starting position

$   Matches the ending position

Capturing Arguments

The pair of brackets is a capture group
Everything captured is passed to method parameter
Cucumber will automatically convert to the method parameter type
Equal number of method parameters and capture groups

@Given("^an owner with a pet called \"Browny\"$")

public void an_owner_with_a_pet_called() {
......
}
@Given("^an owner with a pet called \"([^\"]*)\"$")

public void an_owner_with_a_pet_called(String name) {
......
}

Type Conversion

If the captured string is not in the correct format for type conversion an error will be thrown.
Use regular expressions to capture the correct format string for the type.
Note: Escape regular expression characters with backslash.

Typical Capture Groups

  • (.+) Good for capturing strings and dates
  • \”([^\”]*)\” Captures a string within Double quotes
  • (\\d) Capture decimal numbers only
  • (\\d+\\.\\d+) Capture floating point numbers
  • (true|false) Captures a Boolean value

Date Formats

@Given ("^today is (.+)$")

public void today_is(Date date) {
......
}

Dates are recognized if it’s a format from the DateFormat class.

  • SHORT is completely numeric, such as 12.13.52 or 3:30pm.
  • MEDIUM is longer, such as Jan 12, 1952.
  • LONG is longer, such as January 12, 1952 or 3:30:32pm.
  • FULL is pretty completely specified, such as Tuesday, April 12, 1952 AD or 3:30:42pm PST.

Example-


import cucumber.DateFormat;

@Given ("^today is (.+)$")

public void today_is(@DateFormat ("yyyy-MM-dd") Date date) {
......
}

Tags

The tags can be used when specifying what tests to run through any of the running mechanism.
So tag is uses for grouping Scenarios together

  • Identify slow running test that shouldn’t be run frequently.
  • Identify tests that require a particular library or server.

So we can add tags in our feature file-

@feature
Feature: TestSample

 @one @three
 Scenario: Example
 Given .....
 When ......
 Then ......

 @one
 Scenario: Example Two
 Given .....
 When ......
 Then ......

 @three
 Scenario: Example Three
 Given .....
 When ......
 Then ......

 @ignore
 Scenario: Example Four
 Given .....
 When ......
 Then ......

For the better understanding of tags and there execution please view @CucumberOptions.

Some Useful Liks –
Official website: cukes.info
https://github.com/cucumber/cucumber/wiki
http://behaviour-driven.org/
github.com/cucumber/cucumber-jvm
http://www.engineyard.com/blog/
http://groups.google.com/group/cukes