Abstract
Dafny is a verification-ready programming language that is executed via compilation to C# and other mainstream languages. We introduce a toolkit for automated testing of Dafny programs, consisting of DUnit (unit testing framework), DMock (mocking framework), and DTest (automated test generation). The main component of the toolkit, DTest, repurposes the Dafny verifier to automatically generate DUnit test cases that achieve desired coverage. It supports verification-specific language features, such as pre- and postconditions, and leverages them for mocking with DMock. We evaluate the new toolkit in two ways. First, we use two open-source Dafny projects to demonstrate that DTest can generate unit tests with branch coverage that is comparable to the expectations developers set for manually written tests. Second, we show that a greedy approach to test generation often produces a number of tests close to the theoretical minimum for the given coverage criterion.
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Notes
- 1.
Dafny’s int is compiled to C#’s BigInteger because in Dafny integers are unbounded.
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Acknowledgments
The authors would like to thank Aleks Chakarov, Cody Roux, William Schultz, and Serdar Tasiran for their invaluable feedback on the usability of the toolkit, Ryan Emery and Tony Knapp for facilitating the use of the ESDK as a benchmark dataset, Rustan Leino, Mikael Mayer, Aaron Tomb, and Remy Williams for their feedback on the source code, and the anonymous reviewers for helping improve this text. This work is partly supported by an Amazon post-internship graduate research fellowship.
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Fedchin, A. et al. (2023). A Toolkit for Automated Testing of Dafny. In: Rozier, K.Y., Chaudhuri, S. (eds) NASA Formal Methods. NFM 2023. Lecture Notes in Computer Science, vol 13903. Springer, Cham. https://doi.org/10.1007/978-3-031-33170-1_24
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