Why we use Test-Driven Development when developing our middleware

In modern integration landscapes — particularly where SharePoint, Power Automate, Custom Connectors and CMIS-based archiving systems work together — reliable behavior is not a “nice to have,” but business-critical. That is why we consistently use Test-Driven Development (TDD) in our projects.

The key advantage: TDD minimizes integration risks before they become real problems. Our middleware communicates with several external APIs, which can change in structure, semantics, or timing. By formulating tests before implementation, we clearly define what behavior we expect — and immediately recognize when an external service delivers something that doesn't meet our assumptions. TDD acts like a security system for distributed software architectures.

In addition, the tests serve as an executable specification. Instead of extensive descriptions, we record the desired behavior precisely in test cases. This results in more robust software, clearer design, and development that remains transparent and reproducible — regardless of how complex the data flows are. TDD ensures that requirements are not only documented but can also be precisely verified.

But the most important point — especially in the archiving domain: TDD significantly increases the fault tolerance of our systems. Archiving processes must have no uncertainty. That is why we use TDD not only to model the desired normal behavior, but also those errors that hopefully never occur: incomplete documents, unexpected metadata from SharePoint, network errors towards CMIS, or inconsistent API responses from Power Automate. By testing critical scenarios in advance, we ensure that our systems respond reliably — even when the reality is messer than the ideal.

In short, TDD helps us keep integrations stable, clearly define behavior, and proactively rule out errors in the archiving process. That is exactly why Test-Driven Development is not just a method for us — but an essential part of our quality strategy.