A well-designed Test Automation Architecture (TAA) promotes the reuse of assets across the entire solution. Reusable components, such as a keyword-driven function for a common business process (e.g., user login), inherently span multiple layers of the TAA. The keyword itself resides in the Test Definition Layer, the logic for executing the steps is in the Test Execution Layer, and the code that interacts with the System Under Test (SUT) interfaces is in the Test Adaptation Layer. Therefore, reusable Test Automation Solution (TAS) artefacts are composed of parts from these different architectural layers.

B. A good design is necessary but not sufficient for reuse. Ongoing processes for versioning, maintenance, documentation, and communication are required throughout the TAS lifecycle to support and encourage reuse.

C. While the foundation for reuse is laid during design, the actual communication, maintenance, and improvement of reusable assets are continuous activities that occur throughout the entire TAS lifecycle.

D. Adaptors, which provide the interface to the SUT, are a key component of the Test Adaptation Layer, not the Test Definition Layer. The Definition Layer is concerned with the specification of test cases.

1. ISTQB® Certified Tester Advanced Level, Test Automation Engineer Syllabus, Version 2016.

For Answer A: Section 4.4.1, "Reusability," page 28, states: "Reusable TAS artifacts can include components (or parts of components) associated with different layers of the TAA."

For Answer B & C: Section 4.4.1, "Reusability," page 28, clarifies: "In order to enable reuse of TAS artifacts, a good design for reuse is built into the TAA. However, this is not sufficient. In addition, there must be processes in place to support the reuse of TAS artifacts throughout the TAS lifecycle." This contradicts the idea that no further action is needed or that it's mostly a design activity.

For Answer D: Section 4.2.1, "The generic Test Automation Architecture," Figure 4.1 and the description on page 24, explicitly place "SUT-Interface Adapters" within the "Test Adaptation Layer."