Behavior Driven Testing: Elevating Software Quality

Behavior Driven Development (BDD) is a methodology that emphasizes meeting the business needs of the software. It evolved from test-driven development or TDD, and BDD uses a domain-specific language and a fixed syntax for developing tests.

What is BDD Testing?

Behavior-Driven Development, or BDD, grew out of Test-Driven Development (TDD). TDD aims to create clean, simple code that satisfies the requirements with no or minimal code bloat. In TDD, the aim is to generate code that passes your tests rather than to try to meet your needs directly.

BDD takes this further, using a domain-specific language and a fixed syntax for tests. This provides a framework to specify your features regarding unit and acceptance tests. You must be precise with your language, ensuring you create unambiguous tests. This approach lets you create tests that are closely aligned with the needs of the business. Cucumber was one of the first frameworks for BDD, and it was initially released 10 years ago as a tool for Ruby developers. Their domain-specific language for BDD is called Gherkin.

It’s built around three key statements: Given, When, and Then.

• Given sets up the initial context and defines the starting point of the system. This is where you outline the initial conditions.
• When describes the action that triggers a change or behavior in the system. This is the action that you take to cause an event.
• Then outlines the expected outcome that should occur following the action described in the When statement. This is the result you expect to see.

Importance of BDD in Software Development

Behavior Driven Development Testing serves as a vital link between technical and non-technical stakeholders. It helps you ensure that development projects stay aligned with your business needs. BDD achieves this by clearly defining and testing the system’s behavior before it is built. 

This approach enhances the quality of your code. It provides a clear understanding of what the system should do and ensures it meets those expectations. BDD Testing eliminates ambiguity in requirements. It ensures your software is developed to meet specific business goals. By fostering better communication and alignment, BDD Testing keeps everyone involved on the same page and working towards common objectives.

3 Popular Behavior Driven Testing Frameworks

Here are three widely used frameworks for behavior driven development testing:

Cucumber

Cucumber is one of the most popular platforms for BDD that supports various programming languages, including Java and JavaScript. It uses a Gherkin syntax, which is a human-readable language. This allows writing executable specifications in plain text. Cucumber remains popular within the Ruby developer community due to its familiarity.

SpecFlow

SpecFlow is an open-source testing framework for .NET applications. It enables Behavior Driven Development (BDD) by allowing team members and business stakeholders to collaborate. Teams can define the behavior of their software using natural language specifications written in Gherkin syntax.

Behave

Behave is specifically designed for Python, making it a suitable choice for Python developers. This tool is used for Behavior Driven Development (BDD) and allows writing tests in a simple, natural language format.

How Do I Implement BDD?: 5 Steps 

Here are the essential steps for doing BDD:

1. Plan Tests: Use Cucumber to plan your tests and write them in Gherkin.
2. Define Features: Each line in Gherkin starts with a keyword and defines one aspect of a feature.
3. Write Test Scenarios: Define tests that check if the feature is correctly implemented. 
4. Implement Tests: Use Cucumber to create methods that implement the tests for each feature. Cucumber supports generating methods in languages like Java, JavaScript, or Python.
5. Use Hooks: Define pre- and post-conditions related to tests, such as setting up database states, using Cucumber hooks.

True BDD is a very formulaic approach to automated testing and software development. You plan your tests using Cucumber and write them in Gherkin. Gherkin is a language that allows product teams to define requirements for new features. In Gherkin, every feature is defined in a .feature file and follows a precise syntax. It would be best if you used a Gherkin keyword at the start of each line, and each line defines one aspect. The aim is to create unambiguous definitions for each feature which can then be tested precisely.

You can then define your tests that check the feature is correctly implemented. The most important thing is that every test follows a fixed format: Given some condition, when something happens, then you see a result. Gherkin is intended to be human-readable, but, as with formats such as XML, it isn’t always easy to read!

Having defined your features, you use Cucumber to create methods to implement the tests for each feature. Cucumber was designed for Ruby, but you can also use it to generate Java, JavaScript, or Python methods. Hooks allow you to define pre- and post-conditions relating to the test (e.g., database state).

Why is behavior-driven development so helpful? BDD Benefits

BDD focuses on the end user’s needs and how the software behaves. Importantly, you define your tests simultaneously as you plan your features. Therefore, if your software passes the tests, it implements the correct features, which is a very different approach from usual.

In a 2006 blog, Dan North explained the origins of BDD.

“Behaviour-driven development started life as an NLP exercise to stem the abuse of the word “test” in “test-driven development.”

If a team is already using Test-Driven Development (TDD) or Acceptance Test-Driven Development (ATDD), here are the benefits they can leverage from Behavior-Driven Development:

• BDD provides more precise guidance on organizing conversations between developers, testers, and domain experts, leading to more effective communication and collaboration.
• The notations used in BDD, such as the given-when-then canvas, are designed to resemble everyday language, making it easier for technical and non-technical team members to understand and use.
• BDD tools often offer automatic generation of technical and end-user documentation from BDD specifications, which can save time and improve documentation quality.

Nowadays, everyone assumes NLP means natural language processing, however, in 2006, the acronym stood for neuro-linguistic programming. So, what Dan North meant was behavior-driven development attempts to shift the emphasis from passing tests to testing correct behavior.

A simple example of a BDD feature

The following is a straightforward example of how to write a BDD feature for a login button.

‍Feature: Login button
A user should be able to login by entering their credentials and clicking on a button.
Provided the user enters a valid username and password, the button should take them to
their homepage.

Scenario: User enters valid credentials
Given the user is on a page with the login form
And the user has entered the username “test1”
And the user has entered the password “Pass123”
When he clicks login
Then the user is taken to his homepage

Scenario: User forgets their password
Given the user is on a page with the login fields
And the user has entered the username “test1”
When he clicks the “Forgot password” link
Then the user is taken to the reset password page

Scenario: User enters invalid credentials
Given the user is on a page with the login fields
And the user has entered the username “test1”
And the user has entered the password “Pass321”
When he clicks the login button
Then the login form is displayed again with the username still populated and an error message

As you can see, there are several keywords here: Feature, Scenario, Given, When, Then, And. The tests are clearly defined and easy to understand.

Challenges and Limitations of BDD Testing

The main challenge with BDD is the formulaic nature of Gherkin. This makes it quite challenging for your product team, who are more used to writing user stories. They will have to shift to a different way of thinking. Rather than focus on the user outcomes, they must consider the specific features that should be developed.

Also, it is challenging to combine BDD with Agile development. BDD is ideal in a waterfall model project where your requirements are fixed. But in Agile, you constantly adapt your product to the changing needs of the end-user. This means you will need to rewrite features and tests as you go, which could double the work you would otherwise have done.

How Can I Avoid Common Mistakes?

The most common mistake you can make is to miss out on a critical test scenario. BDD is only as good as the scenarios you define. The key is to encourage your development and product teams to work together. The product owners are the people that can ensure you are describing every scenario.

Another major mistake is believing BDD is the only testing you need. BDD is great for testing features but can’t test usability, UI defects, performance, etc. Moreover, any user interface tests must still be converted into test scripts. In other words, BDD is more about how to write the software rather than how to test it.

Future Trends in Behavior Driven Testing

Behavior Driven Testing (BDT) integrates more closely with DevOps practices. The future of BDT tools is heading towards advanced automation, leveraging AI and Machine Learning. These technologies will enable tools to autonomously manage complex test scenarios, generating, executing, and maintaining test cases based on user stories and requirements. 

As cloud computing continues to expand rapidly, BDD tools and frameworks are poised to evolve in tandem, introducing a new generation of cloud-based testing solutions. You'll find yourself utilizing these solutions for scalability, flexibility, and cost-effectiveness in managing your BDT environments.

You can look forward to the development of more sophisticated tools and frameworks that support BDT implementation. These tools will make it easier for you to automate tests, manage complex scenarios, and integrate BDT into your development workflow.

FAQs on Behavior Driven Development Testing

What is the difference between Behavior-Driven Testing and Test-Driven Development?

The key difference is the scope; Test-Driven Development (TDD) is primarily a development practice where developers write tests before writing the code itself. On the other hand, Behavior-Driven Testing (BDD) is a team methodology that involves creating automated specifications. These specifications are typically written collaboratively by users, testers, and developers to ensure the code under test meets desired behaviors and requirements.

Can BDD be Used for API Testing?

Yes, BDD (Behavior Driven Development) can be effectively used for API testing. It offers a structured approach that simplifies understanding and maintaining test frameworks. BDD's feature files provide clear, user-friendly descriptions of API behaviors. It is accessible to both technical and non-technical team members.

Is Behavior Driven Testing suitable for all types of software projects?

Behavior Driven Testing (BDT) is suitable for most software projects. It enhances communication between technical and non-technical teams to verify software behavior effectively.

Conclusion

• Behavior-driven development enhances software quality by focusing on feature delivery.
• It shifts the emphasis from passing tests to delivering functional features.
• BDD fosters collaboration between teams, improving communication and alignment.
• However, BDD is not suitable for every project and requires team buy-in and understanding.
• Successful BDD implementation depends on clear, well-defined feature specifications.