Conformance testing is the process of verifying that an implementation performs in accordance with a particular standard, specification, or environment. Conformance testing is exclusively concerned with the external behavior of an implementation. Service and functional behavior is tested in order to find logical errors and prerequisites for interoperability.

Conformance testing is not intended to be exhaustive, and a successfully passed test suite does not imply a 100-percent guarantee. But it does ensure, with a reasonable degree of confidence, that the implementation is consistent with its specification, and it does increase the probability that implementations will interwork.

ISO 9646 and TTCN
ISO 9646 is a framework for conformance testing. ISO 9646 incorporates the TTCN language as ISO 9646-3, but it includes other information as well. TTCN in itself in an unspecified environment would not provide means for testing. The specification of that environment is what ISO 9646 is about.

Test Configuration
One part of the standard is the test specification. How the test is set up, the responsibilities of different entities involved, and the handling of the connections between these are all regulated in the standard.

Figure 1 shows the basic conceptual test configuration. The upper and the lower tester are running the implementation under test (IUT), checking the behavior accordingly.

Figure 1. The Conceptual Test Method