Technology Radar
Tests as data over tests as code means expressing test cases as structured data, typically YAML or JSON, rather than as test code. A project-specific test harness reads that data and executes the underlying code: the harness provides the building blocks, while the test cases define how they’re assembled. The technique isn't new; BDD with Gherkin is a prime example. What makes it relevant again is that AI coding agents now write more code, including tests. We’ve found that a defined schema better constrains what they produce, making tests easier to generate and review, with less AI-generated test code.
A few of our teams have also seen a compelling use case in legacy modernization, where the same test cases expressed as data can run against both legacy and modern code by swapping the harness adapter. This helps teams verify that the modernized system behaves like the original, at least for the cases covered by the tests. Using the technique with AI is still relatively new to us, and we haven't applied it broadly. However, the results so far are promising, and we think it's worth assessing.
