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Software testing is a critical skill for computing students, but learning and practicing testing can be challenging, particularly for beginners. A recent study suggests that a lightweight testing checklist that contains testing strategies and tutorial information could assist students in writing quality tests. However, students expressed a desire for more support in knowing how to test the code/scenario. Moreover, the potential costs and benefits of the testing checklist are not yet examined in a classroom setting. To that end, we improved the checklist by integrating explicit testing strategies to it (ETS Checklist), which provide step-by-step guidance on how to transfer semantic information from instructions to the possible testing scenarios. In this paper, we report our experiences in designing explicit strategies in unit testing, as well as adapting the ETS Checklist as optional tool support in a CS1.5 course. With the quantitative and qualitative analysis of the survey responses and lab assignment submissions generated by students, we discuss students' engagement with the ETS Checklists. Our results suggest that students who used the checklist intervention had significantly higher quality in their student-authored test code, in terms of code coverage, compared to those who did not, especially for assignments earlier in the course. We also observed students' unawareness of their need for help in writing high-quality tests. 

Software testing is an essential skill for computer science students. Prior work reports that students desire support in determining what code to test and which scenarios should be tested. In response to this, we present a lightweight testing checklist that contains both tutorial information and testing strategies to guide students in what and how to test. To assess the impact of the testing checklist, we conducted an experimental, controlled A/B study with 32 undergraduate and graduate students. The study task was writing a test suite for an existing program. Students were given either the testing checklist (the experimental group) or a tutorial on a standard coverage tool with which they were already familiar (the control group). By analyzing the combination of student-written tests and survey responses, we found students with the checklist performed as well as or better than the coverage tool group, suggesting a potential positive impact of the checklist (or at minimum, a non-negative impact). This is particularly noteworthy given the control condition of the coverage tool is the state of the practice. These findings suggest that the testing tool support does not need to be sophisticated to be effective. 

Developers and computing students are usually expected to master multiple programming languages. To learn a new language, developers often turn to online search to find information and code examples. However, insights on how learners perform code search when working with an unfamiliar language are lacking. Understanding how learners search and the challenges they encounter when using an unfamiliar language can motivate future tools and techniques to better support subsequent language learners. Research on code search behavior typically involves monitoring developers during search activities through logs or in situ surveys. We conducted a study on how computing students search for code in an unfamiliar programming language with 18 graduate students working on VBA tasks in a lab environment. Our surveys explicitly asked about search success and query reformulation to gather reliable data on those metrics. By analyzing the combination of search logs and survey responses, we found that students typically search to explore APIs or find example code. Approximately 50% of queries that precede clicks on documentation or tutorials successfully solved the problem. Students frequently borrowed terms from languages with which they are familiar when searching for examples in an unfamiliar language, but term borrowing did not impede search success. Edit distances between reformulated queries and non-reformulated queries were nearly the same. These results have implications for code search research, especially on reformulation, and for research on supporting programmers when learning a new language. 

Although there are tools to help developers understand the matching behaviors between a regular expression and a string, regular-expression related faults are still common. Learning developers’ behavior through the change history of regular expressions can identify common edit patterns, which can inform the creation of mutation and repair operators to assist with testing and fixing regular expressions. In this work, we explore how regular expressions evolve over time, focusing on the characteristics of regular expression edits, the syntactic and semantic difference of the edits, and the feature changes of edits. Our exploration uses two datasets. First, we look at GitHub projects that have a regular expression in their current version and look back through the commit logs to collect the regular expressions’ edit history. Second, we collect regular expressions composed by study participants during problem- solving tasks. Our results show that 1) 95% of the regular expressions from GitHub are not edited, 2) most edited regular expressions have a syntactic distance of 4-6 characters from their predecessors, 3) over 50% of the edits in GitHub tend to expand the scope of regular expression, and 4) the number of features used indicates the regular expression language usage increases over time. This work has implications for supporting regular expression repair and mutation to ensure test suite quality. 

Regular expressions are frequently found in programming projects. Studies have found that developers can accurately determine whether a string matches a regular expression. However, we still do not know the challenges associated with composing regular expressions. We conduct an exploratory case study to reveal the tools and strategies developers use during regular expression composition. In this study, 29 students are tasked with composing regular expressions that pass unit tests illustrating the intended behavior. The tasks are in Java and the Eclipse IDE was set up with JUnit tests. Participants had one hour to work and could use any Eclipse tools, web search, or web-based tools they desired. Screen- capture software recorded all interactions with browsers and the IDE. We analyzed the videos quantitatively by transcribing logs and extracting personas. Our results show that participants were 30% successful (28 of 94 attempts) at achieving a 100% pass rate on the unit tests. When participants used tools frequently, as in the case of the novice tester and the knowledgeable tester personas, or when they guess at a solution prior to searching, they are more likely to pass all the unit tests. We also found that compile errors often arise when participants searched for a result and copy/pasted the regular expression from another language into their Java files. These results point to future research into making regular expression composition easier for programmers, such as integrating visualization into the IDE to reduce context switching or providing language migration support when reusing regular expressions written in another language to reduce compile errors.