In regard to OPC Testing for Compliance and Certification the following concepts apply. The actual requirements for certification are defined on a project basis, but the standard third party certification provided by the OPC Foundation provides the following:
Compliance - Assurance that the OPC UA Server or Client fulfils all functionality that it claims to support in terms of Profiles and that of all exposed interfaces function as defined in the specifications.
Interoperability - Testing of products against other products, this includes all functionality, data types and access rights.
Robustness - The testing of failure cases including handling of lost communication, communication recovery. All problems must not affect other connections, quality information must be correctly reported, and audit entries are generated as needed. In short, end users are aware of any problem and problems are resolved automatically where possible.
Efficiency - The testing of products under load, forcing of noisy / bad communications and ensuring that products continue to work. Measuring CPU, RAM, threads, handles etc. and ensuring that even under the poor communications, heavily loaded Servers and Clients continue to function and not leak resources.
Usability - Verify that products are delivered with some level of documentation and that the documentation that is provided is accurate and understandable. Verify that the product functions as advertised and an end user would understand what is being provided.
Certification - Validation of Server or Client products. Certification includes compliance, interoperability, robustness, efficiency and usability testing and results in a seal of approval from an OPC Foundation test lab upon meeting or exceeding defined acceptance criteria.