## The Problem

A SaaS company providing digital marketing and data privacy compliance solutions for European clients had a legacy backend with:

- Low test coverage, leading to frequent production bugs
- Monolithic architecture without layer separation, making it hard to maintain and extend
- Manual deployment process that was error-prone

## The Solution

Complete backend refactoring to a **service–repository pattern** using Go and PostgreSQL.

### Key Changes

- **Service–repository architecture**: separating business logic from data access, improving testability and maintainability
- **RESTful API development**: new endpoints to support digital marketing and data privacy workflows
- **Automated testing**: gradually increasing test coverage from baseline to 75%
- **CI/CD integration**: cross-functional team collaboration using Jira, Bitbucket, and Slack

## Results

- **Test coverage up to 75%**: from a very low baseline
- **Production bugs down 40%** between Q3–Q4 2024
- **More reliable deployments**: new features and bug fixes delivered on schedule
- More readable code with significantly reduced onboarding time for new developers

## Lessons Learned

1. **Test coverage isn't a number, it's a safety net**: the investment in automated testing pays off when every deployment can be done with confidence, not hope
2. **Service–repository pattern is an investment**: despite higher upfront cost, layer separation makes debugging, testing, and feature addition far easier once the foundation is in place
3. **Cross-functional collaboration**: regular communication via Jira and Slack with non-technical teams ensures what's built matches what's needed