Adopting Test-Driven Development (TDD) is critical for a tech company. TDD serves as a strong safety net against bugs caused by code changes. TDD becomes especially important for large code bases that are changed frequently. At the time of this writing, the Trustious code base is around 20,000 commits large, with over 80,000 lines of code, code that changes rapidly. The frequent changes are a natural consequence of the Lean methodology. As a company we firmly believe in Lean and are continuously running Build-Measure-Learn cycles. This requires us to make frequent experimental changes to the user experience which map to frequent changes to the code base (mostly to the front end). With such a rapidly evolving product, writing and maintaining tests that will truly keep us safe, could easily get out of hand.