Centre for Testing & Interoperability * ETSI Approach * Testing Languages * TTCN-3


Writing Test Cases (or TCs) is one of the final steps in the development of a complete test specification. Each TC is an executable test script or program that can be compiled and run on a suitable test system.

The TCs are based on the Test Purposes (or TPs) identified in the relevant standard (or standards) from which the test specification is derived. The entire set of TCs is called a Test Suite (TS).

Nearly all ETSI Test Suites are written in the Testing and Test Control Notation (TTCN). TTCN-3 is developed and maintained by ETSI TC MTS as the ES 201 873 series and by the ITU-T as ITU Recommendation Z.16x series.

Although primarily used in telecommunications, TTCN is well accepted by industry and its use has spread into new domains including automotive, railway and financial applications. Typical areas of application for TTCN-3 are protocols, services, APIs (Application Programming Interfaces), and software modules. However it is not restricted to conformance testing and can be used in areas such as: 

  • Automated Interoperability testing
  • Robustness testing 
  • Performance testing 
  • Regression testing 
  • Load testing 
  • System testing 
  • Integration testing 

Benefits of using TTCN-3

  • It is easy to learn as it has the look and feel of a regular programming language and tutorials, courses, and other publications are available
  • It is different from conventional programming or scripting languages in that it has been specifically designed for testing 
  • It is internationally standardized and off-the-shelf tools and test systems are readily available 
  • It is a flexible testing technology as the language is completely independent of the implementation technology or operating system of the System Under Test 
  • It is scalable, test components can be used both to test or emulate interfaces, it is extensible and has multiple presentation formats

For more information see www.ttcn-3.org.