TDD as a Discovery Tool: Revealing Hidden Business Needs

Bridging the Gap Between Development and Business with TDD

Test-Driven Development (TDD) is often seen as just a technical practice for writing better code. Yet, its true power lies in fostering collaboration and surfacing critical business needs that often go unnoticed. At its core, TDD encourages constant questioning and validation, which naturally leads to conversations about what the software needs to do and why it matters. These conversations, when paired with structured approaches like Collaborative Modeling, Event Storming, and Domain Storytelling, can transform how teams bridge the gap between technical and business perspectives.

Revealing Hidden Business Needs Through Questions

One of the most powerful aspects of TDD is its ability to reveal hidden or unclear requirements through the act of writing tests. Imagine a developer writing a test for a new feature in an e-commerce application: the ability to apply a discount code.

As they define the test, they encounter questions:

• What happens if the code expires?
• Can multiple codes be applied?
• Should discounts stack with other promotions?

Each of these questions is an invitation to engage the business team. Through structured dialogue, the developer and the business representative explore the scenarios, rules, and constraints. These discussions go beyond simple Q&A. They allow developers to understand the motivations behind decisions and challenge unclear or incomplete requirements.

The developer might say:

• "If this rule applies only to first-time users, how do we handle users with duplicate accounts?"
• In turn, the business team might respond:
• "Good point—let's define the rules for account validation more clearly."

This iterative exchange refines the design, ensuring that both sides align on a shared understanding of the feature. Most importantly, it exposes scenarios or edge cases that may not have been considered initially, ensuring the final solution is robust and aligned with real business needs.

The Role of TDD in Collaboration

TDD starts with writing tests based on business requirements. This process naturally encourages developers to engage with business stakeholders to understand what the system should do. However, TDD alone isn’t always enough to ensure a deep understanding of the business domain. This is where collaborative approaches come into play.

Collaborative Modeling: Visualizing Complex Requirements

Collaborative Modeling is a technique where developers and business stakeholders work together to create visual models of the system. These models can include flowcharts, diagrams, or even sketches that represent business processes, user interactions, or system behavior.

How It Helps: By visualizing the system together, both teams can identify gaps, clarify misunderstandings, and ensure that everyone has a shared understanding of the requirements.

Example: A business stakeholder might draw a flowchart of the order fulfillment process, and developers can ask questions to clarify details like how discounts are applied or what happens if an item is out of stock. This process often uncovers missing steps or ambiguous rules that would otherwise remain hidden until later stages of development.

The Role of BDD: Bridging the Gap Further

Behavior-Driven Development (BDD) takes collaboration a step further by using a common language (often called Gherkin) to describe system behavior in a way that both developers and business stakeholders can understand.?

How It Helps: BDD scenarios, written in a "Given-When-Then" format, act as executable specifications that guide development and testing. These scenarios are often created collaboratively, ensuring that everyone agrees on how the system should behave.

Example: A BDD scenario might describe how a customer applies a discount:?

• Given the customer has a promo code with a 10% discount
• And the promo code is still valid and not expired
• And the items in the cart are eligible for discounts
• When the customer applies the promo code at checkout
• Then the total price should be reduced by 10%
• And the discount amount should be shown as a separate line item
• And the final total price should be updated to reflect the discount

Connection to TDD:

BDD scenarios can serve as high-level tests that guide the development of lower-level unit tests in TDD. Together, they create a comprehensive testing and validation strategy that combines technical precision with business insight.

Through iterative refinement of these scenarios, teams often discover edge cases or exceptions that were not initially apparent, ensuring a more thorough coverage of business requirements.

Transitioning from TDD to BDD: Practical Steps

To improve the connection and collaboration between TDD and BDD, teams can adopt the following process:

Start with Small Tests (Unit Tests): Begin by writing technical tests for individual functionalities, such as validating a discount code’s format.

Expand to High-Level Scenarios: Once basic functionalities are tested, move to broader scenarios using BDD. This involves collaborative sessions where developers and business stakeholders draft Gherkin-style scenarios.

Facilitate Role Clarity: Clearly define the roles of team members in creating and refining BDD scenarios. Developers focus on implementation details, while business teams ensure the scenarios reflect real-world needs.

Detailed Example:

Imagine a feature for applying a promo code:

TDD Step: Write a unit test to ensure that the system validates the promo code format (e.g., alphanumeric with a specific length).

Collaborative Modeling: During a workshop, the team visualizes the flow of promo code application—from input to checkout.

BDD Scenario: Define a high-level scenario:

• Given the customer has a valid promo code
• When they enter it during checkout
• Then the discount is applied, and the final price is updated.

By combining these steps, the development process becomes iterative, transparent, and aligned with business goals. At each step, hidden requirements are surfaced and addressed, preventing costly rework later.

Conclusion

By embracing TDD, Collaborative Modeling, and BDD, teams can uncover hidden business needs and create software that not only works technically but also delivers real value to the business. TDD starts the process by surfacing important questions, Collaborative Modeling clarifies requirements visually, and BDD ensures alignment through shared language and testable scenarios.

?

By using these techniques together, teams can create software that goes beyond meeting technical specs—it solves real-world problems. How could combining TDD, Collaborative Modeling, and BDD redefine your approach to development?