Introduction to LangChain: Make AI Smarter and Easier to use

Cucumber is a tool that can execute plain-text functional descriptions. And also it’s BDD(Behaviour Driven Development) automated tests. It is written by Ruby, and now it supports more than 40 languages, such as Java, C# and Scala etc.

Install

Firstly, we need to install Ruby and RubyGems, to check whether the installation of Ruby and RubyGems is successful. You can inputx the commands to terminal, just like as below:

~  ruby --version
ruby 2.0.0p481 (2014-05-08 revision 45883) [universal.x86_64-darwin14]
~  gem --version
2.0.14  

And then we can run the command below to install Cucumber:

~  gem install cucumber

After this, put below command to see how to use it.

~  cucumber --help

Gherkin

Gherkin is a language that can be understand by Cucumber. It’s a Business Readable, Domain Specific Language. Very easy to understand what the functional want to do.

The Gherkin has two purpose, documention and automated test. The structure is Treetop grammer than is part of Cucumber codebase and use indentation to format it.

The Gherkin has two conventions:

• Single Gherkin source file contains a description of single feature.
• The source file is feature extention file(*.feature).

Like YAML(Yet Another Markup Language), Gherkin is a line-oriented language that uses indentation to define structure. Most lines start with keyword. And you can start with a hash sign(#) to comment the text.

A Gherkin source file usually looks like this

 1: Feature: Some terse yet descriptive text of what is desired
 2:   Textual description of the business value of this feature
 3:   Business rules that govern the scope of the feature
 4:   Any additional information that will make the feature easier to understand
 5: 
 6:   Scenario: Some determinable business situation
 7:     Given some precondition
 8:       And some other precondition
 9:      When some action by the actor
10:       And some other action
11:       And yet another action
12:      Then some testable outcome is achieved
13:       And something else we can check happens too
14: 
15:   Scenario: A different situation

Above the codes, It’s very similar with Given-When-Then the Feature, Scenario, Given, And, When, Then all are keywords of Gherkin.