Helmut Neukirchen

Timed TTCN-3 - A Real-time Extension for TTCN-3

The Testing and Test Control Notation (TTCN-3) was originally developed as successor of the second edition of the Tree and Tabular Combined Notation TTCN-3 is a standardized test specification and implementation language to test functional behaviour of distributed systems. TimedTTCN-3 is a real-time extension for TTCN-3 that supports the test and measurement of real-time requirements. TimedTTCN-3 introduces absolute time, allows the definition of synchronization requirements for test components and provides possibilities to specify online and offline evaluation procedures for real-time requirements.

Utilising code smells to detect quality problems in TTCN-3 test suites

Today, test suites of several ten thousand lines of code are specified using the Testing and Test Control Notation (TTCN-3). Experience shows that the resulting test suites suffer from quality problems with respect to internal quality aspects like usability, maintainability, or reusability. Therefore, a quality assessment of TTCN-3 test suites is desirable. A powerful approach to detect quality problems in source code is the identification of code smells. Code smells are patterns of inappropriate language usage that is error-prone or may lead to quality problems. This paper presents a quality assessment approach for TTCN-3 test suites which is based on TTCN-3 code smells: To this aim, various TTCN-3 code smells have been identified and collected in a catalogue; the detection of instances of TTCN-3 code smells in test suites has been automated by a tool. The applicability of this approach is demonstrated by providing results from the quality assessment of several standardised TTCN-3 test suites.

Refactoring and metrics for TTCN-3 test suites

Experience with the development and maintenance of test suites has shown that the Testing and Test Control Notation (TTCN-3) provides very good concepts for adequate test specification. However, experience has also demonstrated that during either the migration of legacy test suites to TTCN-3, or the development of large TTCN-3 test specifications, users have found it is difficult to construct TTCN-3 tests that are concise with respect to readability, usability, and maintainability. To address these issues, this paper investigates refactoring and metrics for TTCN-3. Refactoring restructures a test suite systematically without changing its behaviour. Complementary metrics are used to assess the quality of TTCN-3 test suites. For automation, a tool called TRex has been developed that supports refactoring and metrics for TTCN-3.

TRex - The Refactoring and Metrics Tool for TTCN-3 Test Specifications

Comprehensive testing of modern communication systems often requires large and complex test suites which then have to be maintained throughout the system life-cycle. Industrial experience, with those written in the standardised testing and test control notation (TTCN-3), has shown that this maintenance is a non-trivial task and its burden could be reduced if appropriate tool support existed. To this aim, Motorola has collaborated with the University of Gottingen to develop TRex, a TTCN-3 development environment published under the Eclipse Public License, which notably provides suitable metrics and refactorings to enable the assessment and automatic restructuring of test suites. In this paper we present the TRex tool, which will make it far easier to construct and maintain TTCN-3 tests that are concise and optimally balanced with respect to readability, usability, and maintainability

Controversy Corner: An empirical study of software architectures' effect on product quality

Abstract: Software architecture is concerned with the structure of software systems and is generally agreed to influence software quality. Even so, little empirical research has been performed on the relationship between software architecture and software quality. Based on 1141 open source Java projects, we calculate three software architecture metrics (measuring classes per package, normalized distance, and a new metric introduced by us concerning the excess of coupling degree) and analyze to which extent these metrics are related to product metrics (defect ratio, download rate, methods per class, and method complexity). We conclude that there are a number of significant relationships between product metrics and architecture metrics. In particular, the number of open defects depends significantly on all our architecture measures.

An approach to quality engineering of TTCN-3 test specifications

Experience with the development and maintenance of large test suites specified using the Testing and Test Control Notation (TTCN-3) has shown that it is difficult to construct tests that are concise with respect to quality aspects such as maintainability or usability. The ISO/IEC standard 9126 defines a general software quality model that substantiates the term “quality” with characteristics and subcharacteristics. The domain of test specifications, however, requires an adaption of this general model. To apply it to specific languages such as TTCN-3, it needs to be instantiated. In this paper, we present an instantiation of this model as well as an approach to assess and improve test specifications. The assessment is based on metrics and the identification of code smells. The quality improvement is based on refactoring. Example measurements using our TTCN-3 tool TRex demonstrate how this procedure is applied in practise.

Some Implications of MSC, SDL and TTCN Time Extensions for Computer-Aided Test Generation

The purpose of this paper is to describe how computer-aided test generation methods can benefit from the time features and extensions to MSC, SDL and TTCN which are either already available or currently under study in the EC Interval project. The implications for currently available test generation tools are shown and proposals for their improvement are made. The transformation of MSC-2000 time concepts into TTCN-3 code is described in detail.

An approach and tool for synchronous refactoring of UML diagrams and models using model-to-model transformations

When refactorings are applied to software models that are specified using the Unified Modeling Language (UML), the actual model and the graphical presentation of the model using a diagram need to be distinguished. While UML refactoring tools exist, they typically perform transformations only on the model level and are not able to transform the corresponding diagram as well. Thus, the UML model and the diagram representation of the model may get out of sync. This paper presents an approach that can be used in UML tools to refactor UML models together with their diagrams. To this aim model-to-model transformations are applied to the underlying model as well as to the related diagram. To prove the applicability of this approach, a prototype plug-in for the Eclipse-based Papyrus UML editor has been implemented. The model transformation language Query/View/-Transformation (QVT) is used to specify the transformation of the UML model and the diagrams.

Towards an integrated quality assessment and improvement approach for UML models

Models defined using the Unified Modeling Language (UML) are nowadays common parts of software documentations, specifications and sometimes even implementations. However, there is a broad variety of how UML is used. Reasons can be found, for example, in the lack of generally accepted modeling norms and guidelines, the semi-formal semantics of UML, or the complexity of the language. In practice, these factors inevitably lead to quality problems in UML models that need to be addressed. We investigate and discuss existing work in the field of quality assessment and improvement of UML models and present how we envision an integrated approach to quality assessment and improvement of UML models. We assess a model with a Factor-Criteria-Metrics (FCM) based quality model, detect issues by finding smells and violated metric thresholds in UML models, and improve UML models by applying refactorings using model-to-model transformations.

Communication Patterns for Expressing Real-Time Requirements Using MSC and Their Application to Testing

This paper introduces real-time communication patterns (RTC-patterns) for capturing real-time requirements of communication systems. RTC-patterns for some of the most common real-time requirements are presented. They are formalized by using Message Sequence Charts (MSCs). The application of RTC-patterns to testing is explained by an example. The example shows how real-time requirements which are expressed using RTC-patterns can be related to TimedTTCN-3 evaluation functions.