Automated test generation techniques improve the efficiency of software testing. However, the opacity of the test generation process and concerns about the readability of generated tests make it difficult for software developers to accept them. Developer-centric test amplification creates easy-to-understand test cases by amplifying existing test cases that developers are familiar with and assists developers in integrating them into their test suite. We propose user-guided test amplification to allow developers to guide the test amplification to generate new test cases based on their branch coverage expectations. We create a user-guided test amplification prototype that starts with the method developers want to test, aids developers in communicating which branch should be covered, and assists developers in inspecting and selecting the amplified test cases. We conduct a technical case study with two Java projects and show that our approach cannot always produce a test case to cover a given branch because objects are not initialized with the right parameter values to fulfill the target branch condition. We also perform a user study with 12 software developers to investigate developers' opinions on our approach. The evaluation result shows that the user-guided test amplification generates amplified test cases that developers are satisfied with and is especially useful when developers want to generate tests to cover a specific branch. Connecting the developers' coverage goal and the amplified test cases enables developers to understand and select the test cases more easily.

The most common reason for Continuous Integration (CI) build failures is failing tests. When a build fails, a developer often has to scroll through hundreds to thousands of log lines to find which test is failing and why. Finding the issue is a tedious process that relies on a developer's experience and increases the cost of software testing. Providing CI build test results with additional context in the developer's local development environment could help solve failing tests more quickly. We propose TestAxis, a test result inspection tool that brings CI test results to the Integrated Development Environment (IDE) offering an experience similar to running a test locally. Moreover, it surfaces additional information that is too expensive to collect in local development, for example, a unique view of the code under test that was changed leading up to the build failure. We implement TestAxis as a plugin for IntelliJ and conduct a user study to evaluate its usefulness and performance benefits. The participants solve programming assignments evaluating the three main features: the test results overview, the test code editor, and the changed code under test display. We show that TestAxis helps developers fix failing tests 13.4% to 30.4% faster. The participants found the features of TestAxis useful and would incorporate it in their development workflow to save time. With TestAxis we set an important step towards removing the need to manually inspect build logs and bringing CI build results to the IDE, ultimately saving developers time.