1. Copyright © Siemens AG 2011. All rights reserved. Corporate Technology A Test Scenario Description Language Bridging the gap between model-based testing and test execution languages such as TTCN-3 Dr. Andreas Ulrich Siemens AG, Corporate Technology andreas.ulrich@siemens.com

2. Page 2 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich Overview  Introduction and motivation  Modeling test scenarios  Conclusions

3. Copyright © Siemens AG 2011. All rights reserved. Corporate Technology Introduction and motivation

4. Page 4 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich MBT in practice Baris Güldali, Univ. Paderborn on http://model-based-testing.info/,http://model-based-testing.info/ 2011-08-12: “In the last weeks I have attended many industrial conferences where we conducted many talks on MBT. My impression is that MBT still didn’t reach into people’s hearts. At iqnite conference in Düsseldorf last week, visitors feedback has shown that only 2 % of attending companies are familiar with or have tried MBT.”

5. Page 5 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich Motivation (functional testing of discrete I/O event systems) Limits of current MBT approaches and tools  Rely on models that are expensive to create  Focus on structural coverage of model, but not fault detection  Insufficient support for concurrent interactions Ways out from the “MBT crisis”  Simplify models to carry only essential parts  Support concurrency directly in the model  Provide sound test implementations of known coverage Scenario-based Testing

6. Page 6 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich What is scenario-based testing? Cam Kaner on Scenario Testing, STQE Magazine, Sep./Oct. 2003  The scenario is a story about someone trying to accomplish something with the product under test.  Scenarios are useful to connect to documented software requirements, especially requirements modeled with use cases.  A scenario test provides an end-to-end check on a benefit that the program is supposed to deliver.  Here we use scenarios to systematically test for the fulfillment of requirements on the software system.

7. Copyright © Siemens AG 2011. All rights reserved. Corporate Technology Modeling test scenarios

8. Page 8 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich The ScenTest meta-model – Basic components Static view on the SUT with its external ports and events / messages. Optional graph that links scenarios together. Useful when describing choices over SUT inputs. Used for generating tests across scenarios. Set of scenarios that describe interactions at the SUT’s ports (black- box approach). Each scenario represents a test.

9. Page 9 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich The ScenTest meta-model – Test architecture Class diagram: Type definitions for SUT, ports, messages. Allows for syntactical checks of the model. Component diagram: Instantiation of SUT with its ports. Used as objects in test scenario diagrams.

10. Page 10 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich The ScenTest meta-model – Test architecture (cnt.)  SUT is modeled as a single instance, even if comprised of several distributed components  All ports (i.e. interfaces) of the SUT that are exposed in testing must be defined together with its events / messages  Points of control and observation – SUT inputs and outputs  Points of observation – SUT outputs only  Multi-port system  Black-box testing approach  Assigning event / message types to port types enables validation of test scenario models  e.g. misuse of messages at a given port

11. Page 11 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich The ScenTest meta-model – Test scenarios Sequence diagram: Test scenarios are described as sequence diagrams with object lifelines as defined in the test architecture. Packages: Scenarios can be group using packages. A package contains at most one scenario.

12. Page 12 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich The ScenTest meta-model – Test scenarios (cnt.)  A scenario describes the behavior of a (possibly distributed) SUT as it is observable at its (multiple) ports by an assumed ideal global tester  A scenario describes the expected behavior of the SUT  Derived from system requirements and use cases  System model, no test-specific model  Hence, in testing any observed deviation is a failure  A test scenario starts with an input to the SUT (received message)  Guarantees control over the SUT by a tester  Rules out testing of any oscillating systems that do not stabilize  One scenario relates to one executable test in test generation

13. Page 13 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich ScenTest test scenario modeling – Overview  Basic concepts for behavioral modeling taken from CSP – Communicating Sequential Processes (Hoare 1978)  (MSC) Sequence  (CSP) Prefixing, sequence  (MSC) Loop  (CSP) Recursion  (MSC) Alternative  (CSP) Non-deterministic choice  (MSC) Parallel  (CSP) Concurrency (interleaving)  (MSC) Unless  (CSP) Interruption  Not all concepts are expressible in UML2/MSC!  Some extensions to cope with testing  Requirement tracing  Ignore messages  ignore superfluous SUT outputs  Unless  Exceptional behavior within a defined scope  Optional messages  variant of alternative

14. Page 14 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich ScenTest test scenario modeling – Sequence

15. Page 15 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich ScenTest test scenario modeling – Alternative

16. Page 16 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich ScenTest test scenario modeling – Optional

17. Page 17 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich ScenTest test scenario modeling – Unless

18. Page 18 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich ScenTest test scenario modeling – Parallel

19. Page 19 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich ScenTest test scenario modeling – Loop

20. Page 20 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich ScenTest test scenario modeling – Ignore

21. Page 21 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich ScenTest test scenario modeling – Reference

22. Page 22 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich ScenTest test scenario modeling – Nesting

23. Page 23 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich ScenTest test scenario modeling – Requirements

24. Copyright © Siemens AG 2011. All rights reserved. Corporate Technology Conclusions

25. Page 25 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich The whole picture – How test scenarios fit into the test process with MBT Test Scenarios State-based Models Test Scenario Graph (Activity Diagr., HL-MSC) JUnitTTCN-3... System Descriptions Test Scenario Descriptions Test Execution Languages directly manual Generation of test scenarios Generation of test implementations

26. Page 26 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich Test scenario descriptions – Summary Test scenario descriptions…  Focus on conformance testing for multi-port concurrent/distributed systems  Are more abstract then TTCN-3 descriptions  Test scenarios could be considered as a generalization of Graphical TTCN-3, but are descriptive rather than operational  Allow for correctness checks at pre-compilation time  Could serve as an intermediate description to link and unify different MBT tools Next steps  Complete missing language features for test scenarios  Message templates, local actions, procedure calls  Expand towards describing real-time constraints  Offer a complementary textual representation

27. Copyright © Siemens AG 2011. All rights reserved. Corporate Technology Backup (Test scenario graph)

28. Page 28 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich The ScenTest meta-model – Test scenario graph (Optional) Interaction overview diagram: Dependencies between test scenarios are described here. In particular the diagram captures choices over test scenarios.

29. Page 29 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich The ScenTest meta-model – Test scenario graph (cnt.)  Optional graph to capture dependencies between test scenarios  Supported in UML2 by an interaction overview diagram (variant of an activity diagram; similar to High-Level MSC)  Offers choices over paths over scenarios  Resulting in a fine-granular system specification  Since a test scenario starts with an input  We actually specify choices over test inputs  May contain loops  Paths can be determined using various test generation criteria  Opens up various new modeling facilities  Not all have been elaborated yet, e.g. parallel scenarios (fork/join), nesting of activities, mixed activities / scenario references

30. Page 30 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich ScenTest test scenario graph modeling – Example

31. Page 31 2-Oct-16 © Siemens AG, Corporate TechnologyDr. A. Ulrich Modeling scenario graph and alternative approach vs. Test generator generates tests according to chosen coverage criterion. User models tests explicitly and keeps control over them.