What is Behavior Driven Development?
Behavior Driven Development (BDD) is a branch of Test Driven Development (TDD).
BDD uses human-readable descriptions of software user requirements as the basis for software tests.
Introduction of BDD from Konstantin Kudryashov, the creator of Behat
What is gherkin language?
Gherkin is a Business Readable, Domain Specific Language created specifically for behavior descriptions. Gherkin is a whitespace-oriented language that uses indentation to define structure.
Here is an example of gherkin:
Feature: Some terse yet descriptive text of what is desired
In order to realize a named business value
As an explicit system actor
I want to gain some beneficial outcome which furthers the goal
Additional text...
Scenario: Some determinable business situation
Given some precondition
And some other precondition
When some action by the actor
And some other action
And yet another action
Then some testable outcome is achieved
And something else we can check happens too
The Feature are not parsed by Behat and don’t have a required structure.
Given-When-Then combo, source
Example 1
Scenario: Multiple Givens
Given one thing
Given another thing
Given yet another thing
When I open my eyes
Then I see something
Then I don't see something else
Example 2
Scenario: Multiple Givens
Given one thing
And another thing
And yet another thing
When I open my eyes
Then I see something
But I don't see something else
Scenario Outline can reduce tedious and repetitive scenario setting by using a template with placeholders
Scenario Outline: Eating
Given there are <start> cucumbers
When I eat <eat> cucumbers
Then I should have <left> cucumbers
Examples:
| start | eat | left |
| 12 | 5 | 7 |
| 20 | 5 | 15 |
Don’t confuse tables with scenario outlines
Scenario:
Given the following people exist:
| name | email | phone |
| Aslak | aslak@email.com | 123 |
| Joe | joe@email.com | 234 |
| Bryan | bryan@email.org | 456 |
Outlines declare multiple different values for the same scenario, while tables are used to expect a set of data.