In TAE, "design for testability" includes attributes that make it easier to create, execute, and maintain automated tests across levels (component, integration, system, UI). The need to define precisely which interfaces are available at different test levels-e.g., public APIs, service endpoints, message queues, UI automation hooks, test seams, logs, and internal test interfaces-maps most directly toarchitecture transparency. Architecture transparency concerns how clearly the system's structure, layers, and accessible interfaces are documented and exposed so test automation can reliably connect to the right interaction points.
This includes understanding which interfaces are stable, supported, and appropriate for each level of testing, and avoiding "guesswork" that increases brittleness. Controllability is about the ability to set inputs, states, and preconditions (e.g., reset data, seed databases, drive system state). Observability is about the ability to see outputs, internal states, and logs to assess outcomes. Autonomy concerns whether tests can run independently without external dependencies or manual intervention (e.g., isolated environments, stable test data). While controllability/observability/autonomy are critical for automation, the specific emphasis on "precisely defining which interfaces are available" is fundamentally an architectural transparency issue: clear interface availability and documentation enable correct, maintainable automation connections across test levels.