Context Tangled commits are changes to software that address multiple concerns at once. For researchers interested in bugs, tangled commits mean that they actually study not only bugs, but also other concerns irrelevant for the study of bugs. Objective We want to improve our understanding of the prevalence of tangling and the types of changes that are tangled within bug fixing commits. Methods We use a crowd sourcing approach for manual labeling to validate which changes contribute to bug fixes for each line in bug fixing commits. Each line is labeled by four participants. If at least three participants agree on the same label, we have consensus. Results We estimate that between 17% and 32% of all changes in bug fixing commits modify the source code to fix the underlying problem. However, when we only consider changes to the production code files this ratio increases to 66% to 87%. We find that about 11% of lines are hard to label leading to active disagreements between participants. Due to confirmed tangling and the uncertainty in our data, we estimate that 3% to 47% of data is noisy without manual untangling, depending on the use case. Conclusion Tangled commits have a high prevalence in bug fixes and can lead to a large amount of noise in the data. Prior research indicates that this noise may alter results. As researchers, we should be skeptics and assume that unvalidated data is likely very noisy, until proven otherwise.

Experience has shown that the Testing and Test Control Notation version 3 (TTCN-3) language provides very good concepts for adequate test specification, but it was not presented yet how large test systems written in TTCN-3 are structured. This paper presents my efforts to analyze the structure of TTCN-3 projects, to see if such problems manifest, and if possible to provide methods that can detect these problems.

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This paper examines how ISO/IEC 9126-1 and ISO/IEC 25010 quality models can be applied to software testing products in industrial environment. We present a set of code smells for test systems written in TTCN-3 and their categorization according to quality model standards. We demonstrate our measurements on industrial and ETSI projects, and provide a method for estimating their effects on product risks in current projects.

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