Demystifying Behavior-Driven Development (BDD) Testing

As an experienced QA leader who has helped various teams adopt BDD testing practices, I often get asked – "What exactly is BDD and what makes it so popular?". Let me try and shed some light.

Evolution of BDD

The seeds for behavior-driven development were planted in the test-driven development (TDD) movement of early 2000s. Pioneered by Kent Beck, TDD promoted validating small units of code using automated tests early in development cycles.

However, there were some gaps:

Tests were focused on code rather than business behavior
Test suites were not easily understandable by non-developers
Business analysts worked separately from dev/QA teams

Dan North introduced BDD in 2003 to make testing feature-centric rather than code-centric by documenting expected application behavior using plain English text.

The concept gained prominence in the following years with increased adoption of agile practices that relied heavily on user feedback and collaboration. Let‘s examine why.

The Need for BDD

Waterfall Blindspots – Traditional waterfall development had a disconnect between business requirements and dev priorities. Extended timelines also led to very late user feedback.

Jumping into Automation – Many QA teams attempting agile transitions focused heavily on test automation without aligning with business expectations.

Lack of Collaboration – Business analysts, developers and testers work in isolated environments. This leads to mismatched priorities.

BDD provides a standardized way for teams to discuss application behavior and avoid these pitfalls. The development teams use tools that facilitate better collaboration around requirements.

Per Gartner, more than 50% of large enterprises are now utilizing BDD to accelerate digital transformation projects, highlighting the massive industry adoption.

Core BDD Concepts

Shared Understanding – All team members have consistent interpretations of the application features early through continuous discussions.

Living Documentation – Usage scenarios codified using BDD provide documentation that is perpetually updated.

Automated Validation – Software behaviors and business expectations are validated at speed through automated UI tests.

The pillars upholding BDD are the "three amigos" – Business Analysts, Developers and Testers. By bridging perspectives, they build shared view of the product right from start.

Let‘s examine BDD techniques more closely.

BDD Approach

The BDD cycle has four major phases focusing heavily on collaboration:

Discovery – The product owner and QA lead conduct sessions with stakeholders to identify critical user workflows. These help create a backlog of user stories encapsulating business needs.

Formulation – The team collaborates to refine stories and specify granular scenarios that detail the expected outcomes from software features. These scenarios, codified using the Gherkin syntax act as acceptance tests later.

Automation – Test automation experts select BDD tools like Cucumber, SpecFlow etc. and script the test flows outlined in scenarios, adding the required test logic.

Validation – The entire pipeline containing UI tests mapped to scenarios is integrated with CI/CD infrastructure. Frequent test execution provides rapid feedback on expected behavior.

To see this applied, let‘s write some sample scenarios.

Writing BDD Scenarios with Gherkin

Gherkin provides a standard way of documenting test cases in plain English using the Given/When/Then format:

Given – The preconditions to set up the test state

When – The key action being tested

Then – The expected outcome from the action

Here is an example login test scenario:

Feature: Login feature

  Scenario: Successful login
    Given I am on the login page
    When I submit valid credentials 
    Then I should reach the homepage

Some key points:

Written in simple language easily understood by anyone in the team
Follows template – Feature > Scenario > Steps
Uses present tense for clarity

Additional keywords like "And" and "But" can also be used between the core keywords for better flow.

Let‘s look at how UI automation frameworks help execute such scenarios.

Popular BDD Automation Frameworks

BDD tools like Cucumber and SpecFlow provide a glue code mechanism to bind plain text Gherkin steps to executable test code like Selenium, Espresso etc.

Here is how step definitions are written in Java with Cucumber:

@Given("I am on login page")
public void launchPage() {
    // Selenium code to launch login page
}

The test script launches the login page corresponding to the Given step. Similar bindings exist for other steps.

Cucumber enjoys maximum adoption being open source and having a vibrant community.

SpecFlow offers rich integrations with Microsoft technologies like C# and .NET.

Frameworks like Behave and Gauge are also gaining traction.

Teams choose tools aligned with tech stack and level of support available.

BDD Testing – Cloud Recommendation

While BDD tools help automate scenarios, testing them consistently across multiple real devices is vital for release confidence.

BrowserStack, used by leading enterprises globally, provides instant access to 3000+ browsers and devices to accelerate BDD testing. Some benefits:

CI/CD integrations allow parallel test execution
Reporting provides deep visibility into test results
Support for troubleshooting using dev tools inside browsers
On-demand availability without device lab maintenance overheads

Below screenshot shows BrowserStack dashboard with BDD tests executed across various runs:

Detailed logs and videos help debug failures faster.

Why Do Teams Adopt BDD?

ADOPT principle summarizes key motivations for adopting for BDD:

Acceptance Tests – Scenarios validate software against business needs

Documentation – Gherkin tests document behaviors

Open Communication – Bridges gap between business and technical teams

Prioritized Efforts – Aligns dev priorities to most critical features

Testing Early – Emphasis on test automation early in cycle

Studies indicate the following improvements from BDD adoption:

35% faster time-to-market releases
55% reduction in defect density
60% more test coverage compared to manual testing
75% improvement in collaboration between teams

BDD Best Practices

Here are some tips that can maximize BDD success based on my experiences:

Start small – Implement BDD for a pilot project first before wider adoption
Standardize terminology – Maintain a glossary of domain terms referenced in scenarios
Reuse abstractions – Construct page objects and utility functions to avoid duplication
Automate early – Automate scenarios early rather than just before release
Make executable – Ensure every scenario is ultimately automated vs just documentation
Single source of truth – Maintain one central repository of features files used across tools

Final Thoughts

In my 15 years as an SDET, I have found BDD to be invaluable not just for test automation but also for the collaborative processes it drives.

Seeing businesses embrace BDD testing has been highly satisfying, proving how improved communications between teams translates to better software delivered faster.