A retrospective on developing the W CARE service frontend with TDD

This introduces a case where a highly complex menstrual event detection algorithm was implemented using the TDD (Test-Driven Development) methodology during frontend development of W CARE, Oliveyoung's women's care service.

A woman's menstrual cycle is variable depending on physical and mental factors, which leads to complex cases where various events such as menstruation, fertile window, and PMS overlap with one another. To solve these complex requirements, the developer split the algorithm into small functions according to concerns and adopted a unit-test-centered strategy that verifies fixed outputs for fixed inputs.

The main development strategies are as follows:

• Incremental development: Repeating the cycle of 'write a failing test → write working code → get feedback → improve code' to refine the algorithm.
• Boundary Value Analysis: Creating test cases with data at the boundary points where events start or end, to prevent edge-case issues.
• Modularization: Designing the complex logic to be easily testable by breaking it down into small-unit functions.

As a result, instead of relying on human memory, static code and tests made it possible to reliably verify 23 different menstrual event cases.