The rise of graph processing has led to an increase in the usage of graph databases and the availability of various frameworks. Graph databases have become more accessible and, in specific instances, can compete with relational databases. Testing an application with a relational database backend has shown limited test coverage, and current test generators cannot cover every branch condition in graph processing applications. There is a lack of test methods specifically designed for applications that utilize graph structures.
This paper presents PGFuzz, a coverage-guided, schema-aware fuzzer for graph processing applications. PGFuzz utilizes existing graph generators to generate inputs and applies graph-specific mutations to alter the graph state. These mutations are schema-aware, designed to cover the graph model search space and satisfy logical conditions from real-world applications. The mutations involve adding new graph elements, removing graph elements, modifying existing elements, altering property values, and violating graph constraints. When compared against existing graph generators and a random byte mutation approach on the nine real-world examples in our benchmark suite, PGFuzz demonstrates an increase in coverage over time and detects more logic errors than the other methods. PGFuzz can cover all previously uncovered branching.