Hey there! If you‘ve been hearing about Behavior-Driven Development recently and wondering what all the fuss is about, you‘ve come to the right place.
With over 10 years of expertise in test automation under my belt, I‘ve had the opportunity to work on 3500+ browser and device combinations using a variety of techniques – and BDD is one of the best.
In this detailed guide, we‘ll uncover all things BDD – from its core concepts to tools, trends and best practices. Even if you‘ve never written a single test before, I‘ll explain everything in simple language with plenty of examples so you can confidently get started.
So, whether you just want to learn about BDD or hit the ground running with adoption, grab a beverage and let‘s get started!
What Exactly is Behavior-Driven Development?
Behavior-Driven Development or BDD is a collaborative software development approach that focuses on defining application behavior that caters to business needs.
The key motivation behind BDD is to address the disconnect between technical implementations and business expectations that plague so many software projects.
BDD bridges this gap by enabling continuous discussions between three key stakeholders:
- Business: Subject experts who clarify what users want
- Development: Engineers who code the application
- QA: Testers who validate expected functionality
These "three amigos" use examples and natural language to describe the behavior expected from the system. The emphasis here is on behavior, not technical requirements.
For instance, saying:
"The system will have a checkout page with a payment form"
is a requirement statement.
Whereas:
"When a registered user adds items to cart and clicks checkout, they must be able to make a payment to place the order"
describes a business-focused behavior.
Such well-defined behaviors then drive discussions, development and testing activities.
Why is BDD gaining such momentum?
The global BDD testing tools market is projected to grow at a 24% CAGR through 2029 as per Market Research Future.
So what‘s driving such rapid adoption?
- Digital transformation: With businesses relying heavily on software, alignment with user needs is vital for software success
- Need for speed: Lean enterprises want to build quality software faster
- Competitive advantage: Well-designed digital experiences are a differentiator
- Testing bottlenecks: BDD test automation boosts efficiency
- Higher ROI: Software that clearly meets business intents drives higher ROI
As organizations recognize BDD‘s tangible benefits, growth has skyrocketed. In fact, almost 70% of organizations are expected to leverage BDD by 2025 as per TechAhead.
BDD Principles and Practices
Now that you know what BDD is and why it matters, let‘s look at some core principles and processes that make BDD work:
Starting with "Why"
BDD teams always start by asking "Why is this feature needed and how will it impact customers?" before getting into solutions. This prevents wasted effort from building features users neither need nor want.
Evaluating Trade-Offs
Every feature adds complexity so BDD teams consciously evaluate trade-offs between effort and value. Simple solutions that deliver 80% value with 20% effort get priority over complex ones with lower ROI.
Discussing Examples
BDD insists product owners and testers collaborate to define example scenarios even before coding starts. What should users see after login? How should the system respond to invalid data? Such examples clarify expected behavior.
Speaking a Common Language
BDD uses a standard ubiquitous language understandable to both tech and non-tech teams. No complex technical jargon is allowed in BDD discussions!
Automating Tests Early
BDD scenarios get automated into test cases early on using frameworks like Cucumber and SpecFlow. This provides quick feedback and protects against deviations from desired behavior.
Let‘s see these BDD principles in action with a case study from one of my past engagements.
Real-World Example: Building an Insurance App
RapidInsure, a leading insurance provider, wanted to enable customers to buy policies online quickly.
Traditionally, building the portal would have started with technical tasks – choose frameworks, map databases, design UI wireframes etc.
With BDD however, we began by asking business stakeholders:
"What typical customer journeys are we enabling here?"
This led to discussions around examples like:
Sam, 25 years old, wants the lowest premium policy to cover his new car.
Lisa, a 42-year old homeowner, wants to compare rates across insurers before choosing the best home insurance.
Such concrete examples helped crystallize expected functionality beyond just "customers should be able to buy insurance online".
We documented these discussions into BDD-style scenarios even before developers wrote any code:
Scenario: Compare home insurance rates
Given Lisa wants home insurance
When she enters her details
Then she can view quotes from multiple providersThese scenarios were the north star guiding development efforts. Code was written to make tests pass, not blindly build infrastructure.
Automated checks ran in parallel, providing rapid feedback when behavior deviated.
This alignment between business intent and technical implementation was the key to RapidInsure‘s portal success, catapulting sign-ups beyond expectations.
This is the transformative power of BDD. Now let‘s unpack more specifics around BDD adoption.
BDD Tools and Frameworks
Specialized tools and frameworks help automate the examples and scenarios defined by BDD:
| Framework | Language | Key Features |
|---|---|---|
| Cucumber | Multiple | Simple syntax, great for non-devs, robust ecosystem |
| SpecFlow | .NET | Seamless integration with Visual Studio and .NET stacks |
| Behave | Python | Python native BDD framework, easily scalable |
| JBehave | Java | Mature framework for Java and JVM projects |
Cucumber is the most popular open-source tool that enables writing tests in plain business language leveraging Gherkin syntax.
Here‘s a sample Gherkin scenario:
Feature: Login
Scenario: Successful login
Given I am a registered user
When I enter valid credentials
Then I should see the homepageThe plain language steps then connect to code via glue scripts to drive test automation. I‘ll unpack more details on running automated checks later.
SpecFlow brings this BDD approach to .NET projects and is widely used by enterprise teams in that ecosystem.
Let‘s now look at some emerging innovations in the BDD space as we step into 2023.
BDD Innovations to Watch Out for in 2024
The rapid adoption of BDD has spawned exciting new trends and innovations:
Smart NLP-based assistants that convert simple English conversations into executable BDD scenarios are emerging. For example, Sacramento from Kovai is an AI assistant that understands natural language to autocreate test cases. I anticipate using such tools to further democratize test creation soon.
Codeless test automation is also gaining significant mindshare by empowering non-developers to create automated checks without needing to code. Platforms like Functionize leverage computer vision and ML to convert UI actions into scripts – expect more such solutions soon.
Leveraging BDD for security testing is an evolving trend where behavior describing misuse cases – account takeover attempts, injection attacks etc. are defined upfront as part of development flows using BDD frameworks. These then get automated into security test cases.
Custom DSLs for specific domains like healthcare, finance with pre-built domain vocabulary and templates are beginning to emerge for wider BDD adoption across industries where domain knowledge is key.
IDE tight integration is also progressing rapidly with BDD plugins for IDEs like IntelliJ, VS Code and Visual Studio providing intuitive interfaces to author scenarios and auto-complete step definitions. SOLID BDD is one such impressive extension for VS code.
BDD Best Practices
Even with the right tools, implementing BDD the right way is key to realizing benefits.
Here are some best practices I always recommend teams adopt:
Start small, iterate fast: Begin with the simplest flow before adding complexity. Quick iterations with consumer feedback outperform big bang launches.
Focus on behavior over tools: Learn to articulate expected behavior clearly in plain language before jumping into tools. Frameworks only help automate the scenarios.
Reuse step definitions: Don‘t reinvent the wheel writing every step from scratch. Create a library of workflow-based reusable step definition modules. Complex page-specific actions are best avoided.
Utilize backgrounds: Common preparatory steps needed across tests like login sequences are best modeled under Background in feature files for reuse.
Employ scenarios outlines: Variations in input data are managed via example tables and scenario outlines avoiding duplication.
Create a ubiquitous language: Domain vocab specific to the business context e.g. Customer, Policy, Premium for insurance vertical can help standardize communications.
A Peek Into Advanced BDD Test Automation
While it‘s easy to start automating basic BDD checks, some key skills take it to the next level for maximum ROI:
- Interface with test management platforms like BrowserStack to run BDD suites across environments, generate reports and monitor progress
- Integrate with CI/CD pipelines so tests execute on every commit providing rapid feedback
- Add custom outputs and plugins like screenshots or videos when tests fail for debugging
- Parameterize tests across inputs, environments so same tests cover multiple scenarios
- Distribute test execution across grids for faster test cycles
- Generate living documentation that stays current even as tests evolve
- Use source control for tests to enable versioning and traceability
Let‘s briefly see BDD test automation in action.
Walkthrough: Automating a Sample BDD Test
Let‘s automate the simple login test we saw earlier into an automated check using Java + Selenium + JUnit + Cucumber:
Feature File
Feature: Login
Scenario: Successful Login
Given I am on the login page
When I submit valid credentials
Then I should see the homepageJava Step Definitions
//imports
public class LoginSteps {
@Given("I am on the login page")
public void launchLoginPage() {
// selenium code to launch login page
}
@When("I submit valid credentials")
public void enterCredentials() {
// code to enter username, password
}
@Then("I should see the homepage")
public void verifyHomepage() {
//assertion code
}
} On executing the CucumberRunner class, steps in the feature file will invoke corresponding Java step def code to drive browser test execution.
Powerful stuff! With some practice, even complex end-to-end business journeys can be automated in this fashion.
Tracking ROI from BDD Initiatives
Like any software program, measuring ROI is vital for BDD.
Here are key metrics I normally track:
Story acceptance rate: Percentage of stories that pass acceptance criteria
Production defect rate: Defect escape rate into production post release
Test automation coverage: Percentage of test cases automated
Lead time: Average time from story prioritization to deployment
MTBF: Mean time between feature failures
Of course, alignment with business intent cannot be measured directly. But taken together, improvements in the above KPIs demonstrate enhanced quality and velocity from BDD adoption.
Now that we‘ve covered the fundamentals, let‘s look at scaling BDD across larger initiatives.
Scaling BDD Initiatives Across Organizations
For larger programs, BDD requires some key enablers:
Top-down leadership support is vital for enterprise-wide change. When leaders endorse BDD, adoption barriers disappear and teams get serious.
Pilots help demonstrate local wins and best practices that can be transferred to other teams. Think big, start small!
Communities of practice create safe spaces for teams to learn from each other. War stories from peers are great motivation.
Incentives that highlight benefits beyond metrics e.g. pride in mastery help fuel intrinsic motivation to climb the BDD learning curve.
Toolchain integration prevents fragmented experiences with disjoint systems that hamper collaboration. Align tools to business goals!
With these aspects accounted for, I‘ve seen even large regulated multinationals succeed with BDD transformations comprising thousands of tests.
So be ambitious, but stay grounded in business realities. Now, let‘s glimpse into the future of BDD.
What Does the Future Hold for BDD?
If the growing momentum is anything to go by, BDD is already on its way to fundamentally reshape software design and testing.
Rapid evolution of supporting tools promises to reduce the barrier to adoption for many more teams globally.
With capabilities like smart test case generation, codeless test creation, seamless IDE integration and custom DSLs, BDD is poised become accessible to business users outside traditional testing roles.
As BDD gets ingrained within developer workflows, I foresee almost every team leveraging BDD practices in some form within the next 5 years.
The future is indeed bright for BDD!
So there you have it – a complete low-down on Behavior-Driven Development. I hope this detailed guide helped demystify the world of BDD and got you excited to adopt it within your projects.
If you have any other questions, feel free to reach out over email. I‘m always happy to help spread awareness on smarter testing approaches!
Here‘s to building better software together.
