Automated Synthesis of Metamorphic Relations from Existing Test Cases

Core Concepts

Existing developer-written test cases can embed domain knowledge that encodes metamorphic relations (MRs). MR-Scout automatically discovers and synthesizes these encoded MRs from test cases in open-source software projects to enable automated test case generation.

Abstract

The paper proposes MR-Scout, an automatic approach to discover and synthesize MRs from existing test cases. MTC Discovery Phase: MR-Scout derives two principal properties that characterize an MR-encoded test case (MTC): (1) containing at least two method invocations of the same class, and (2) containing at least one assertion that validates the relation between the inputs and outputs of the method invocations. MR-Scout checks these properties in test cases from open-source projects to discover MTCs. MR Synthesis Phase: For discovered MTCs, MR-Scout deduces the constituents of the encoded MRs, including the source input, follow-up input, input transformation, source output, follow-up output, and output relation assertion. MR-Scout then codifies these constituents into parameterized methods called "codified MRs" to facilitate automated test case generation. MR Filtering Phase: MR-Scout filters out codified MRs that demonstrate poor quality in applying to new test inputs, as codified MRs not applicable to new inputs are ineffective for new test generation. The evaluation shows that MR-Scout can discover over 11,000 MTCs from 701 open-source projects, with over 97% precision. Over 97% of the synthesized codified MRs are of high quality for automated test case generation. The codified-MR-based tests also effectively enhance the test adequacy of programs with developer-written tests.

Stats

The length of the shortest path should be the same in either direction (a to b or b to a): |f(a,b,G)| = |f(b,a,G)|

Quotes

"Metamorphic Testing (MT) alleviates the oracle problem by defining oracles based on metamorphic relations (MRs), that govern multiple related inputs and their outputs." "We observe that developer-written test cases can embed domain knowledge that encodes MRs. Such encoded MRs could be synthesized for testing not only their original programs but also other programs that share similar functionalities."

Key Insights Distilled From

MR-Scout

by Congying Xu,... at arxiv.org 04-03-2024

https://arxiv.org/pdf/2304.07548.pdf

Deeper Inquiries

How can MR-Scout be extended to handle more complex MRs that involve logical operators or multiple output relations?

To handle more complex MRs involving logical operators or multiple output relations, MR-Scout can be extended by incorporating advanced pattern recognition techniques. This extension would involve enhancing the analysis of assertion statements to identify and differentiate between simple boolean expressions and more complex logical relationships. One approach could be to develop additional assertion patterns that can capture the presence of logical operators such as AND, OR, XOR, and EXOR. By expanding the set of patterns used to recognize relation assertions, MR-Scout can better distinguish between simple assertions and those that involve more intricate logical operations. Furthermore, the extension could involve implementing more sophisticated algorithms for parsing and interpreting assertion statements. This could include leveraging natural language processing techniques to extract and analyze the semantics of the assertions, enabling MR-Scout to identify and handle complex logical relationships more effectively.

What are the potential limitations of MR-Scout in handling test cases with advanced programming constructs like inheritance, polymorphism, or concurrency?

While MR-Scout is a valuable tool for automatically synthesizing MRs from existing test cases, it may face limitations when handling test cases with advanced programming constructs like inheritance, polymorphism, or concurrency. Some potential limitations include: Inheritance: Test cases involving inheritance can introduce complexities in identifying the relationships between classes and their methods. MR-Scout may struggle to accurately trace method invocations across different classes in an inheritance hierarchy, leading to challenges in deducing the constituents of MRs. Polymorphism: Test cases that utilize polymorphism can present challenges in determining the specific method implementations being invoked at runtime. MR-Scout may encounter difficulties in differentiating between different implementations of polymorphic methods, impacting the accuracy of synthesized MRs. Concurrency: Test cases involving concurrency introduce non-deterministic behavior, making it challenging to predict the order of method invocations and their outcomes. MR-Scout may struggle to handle scenarios where multiple threads interact with shared resources, leading to potential inaccuracies in deducing MRs related to concurrent execution. Complex Interactions: Advanced programming constructs often result in complex interactions between classes and methods, making it harder for MR-Scout to accurately identify and synthesize MRs that capture the intricate relationships between inputs and outputs in such scenarios.

How can the comprehensibility and practical adoption of the synthesized MRs by developers be further improved?

To enhance the comprehensibility and practical adoption of the synthesized MRs by developers, the following strategies can be implemented: Documentation and Explanation: Provide detailed documentation and explanations for each synthesized MR, including the rationale behind its formulation, the input-output relationships it captures, and examples of its application in testing scenarios. This will help developers understand the purpose and utility of the MRs. Visualization: Use visual aids such as diagrams, flowcharts, or examples to illustrate how the MRs relate to the test cases and the expected outcomes. Visual representations can make complex concepts more accessible and easier to grasp. Training and Workshops: Conduct training sessions or workshops to educate developers on the concept of MRs, their significance in testing, and how to effectively utilize synthesized MRs in test case generation. Hands-on exercises and real-world examples can enhance understanding and practical application. Integration with Testing Tools: Integrate the synthesized MRs directly into popular testing frameworks or tools used by developers. This seamless integration will make it easier for developers to incorporate MR-based testing into their existing workflows. Feedback Mechanism: Establish a feedback mechanism where developers can provide input on the usefulness and clarity of the synthesized MRs. Incorporating developer feedback will help refine the MR synthesis process and tailor it to the specific needs and preferences of the users.