© 2017 Lukman Ab. Rahim, Ziyaulhaq Aliyu and Emy E. Mustapha. This open access article is distributed under a Creative Commons Attribution (CC-BY) 3.0 license. Journal of Computer Sciences Original Research Paper Evaluating the Usability of Model Transformations Testing Approach (MTTA) Lukman Ab. Rahim, Ziyaulhaq Aliyu and Emy E. Mustapha Department of Computer and Information Sciences, Universiti Teknologi PETRONAS, 31750, Tronoh, Perak, Malaysia Article history Received: 30-12-2015 Revised: 01-03-2016 Accepted: 25-01-2017 Corresponding Author: Lukman Ab. Rahim Department of Computer and Information Sciences, Universiti Teknologi PETRONAS, 31750, Tronoh, Perak, Malaysia Email: lukmanrahim@petronas.com.my Abstract: Model Transformation (MT) is a key component in Model Driven Development (MDD). Model transformation is used to transform source model into a target model, improve the model quality and also introduce the design pattern and refactoring. Model transformation are not free from bugs similar to other software development artifacts and it needs to be verified. Code Generators (CG) are a type of model transformation that automatically generate code from software models. To verify a CG using Model Transformation Testing Approach (MTTA) effectively, MTTA requires the users to manually generate test model and develop assertions. Since both tasks are performed manually, a usability study is conducted to gauge the effects of the manual tasks towards the usability of MTTA from three perspective: Learnability, effectiveness and efficiency. The aim of this paper is to identify the usability problems of MTTA related to its learnability, efficiency and effectiveness. Usability test technique is used in this study and questionnaire was used to collect a quantitative data from the participants. A pilot test was conducted with two participants and later eight participants were recruited for the real test. The result shows that MTTA is learnable and effective but inefficient. We conclude with a discussion on the reason why MTTA is inefficient. Keywords: Model-Driven Engineering, Model Transformation Testing, Verification, Usability Introduction It is familiar that the integral complex nature of software systems increases the challenges of software development (Lin, 2007). Abstraction and automation are among the prominent techniques for addressing software development complexity (Lin, 2007; Narayanan, 2008). The aim of model Driven Engineering (MDE) is to increase the level of abstraction in program specifications by the use of models at different levels of software development and improve automation in program development using executable model transformations. High level models are transformed into lower level until these models become executable by the use of either model interpretation (model-to-model transformation) or code generation (model-to code transformation) techniques (Frankel, 2003; Kleppe et al., 2003; Selic, 2003). Model Transformations (MTs) are used to synthesize various types of artifacts from models or refine models to capture more system details. This shows that model transformations play a key role in MDE for converting models to other software artifacts. The main objective of MTs are to provide automation in MDE, to reduce the human effort that is associated with modeling and also to reduce the potential errors complexity (Lin, 2007; Narayanan, 2008). The description of how source language constructs may be transformed into target language constructs are referred to as transformation rules. Various methods may be used for defining the transformation rules, such as Query View Transformation (QVT) and Atlas Transformation Language (Bézivin et al., 2003) (refer to (Czarnecki and Helsen, 2006) for more detail). Majority of these languages concentrate on the transformation implementations but usually not their verification (Guerra et al., 2013). However, as like other software artifact, models transformations are not free from bugs, therefore they need to be verified (Ab Rahim and Whittle, 2010). The main important principal of verification is to discover the defects in