Test Case Generation for Ethereum Smart Contract based on Data Dependency Analysis of State Variable

An Ethereum smart contract is an agreement reached by multiple parties, which is guaranteed by blockchain technology to be executed in accordance with the terms expressed in the form of code. Its security needs are particularly prominent due to a large number of digital assets under management. Testing is an effective way to find flaws that threaten the security of smart contracts. However, current smart contract test case generation methods do not regard the impact of other functions in the smart contract on state variables, resulting in the inaccessibility of the control statements related to state variables and low branch coverage of the function under test. To alleviate this problem, this paper proposes SV-Gen. SV-Gen generates test cases for smart contracts through two steps: static analysis and dynamic search. In the first step, SV-Gen considers the read-write relationship between functions and state variables in the smart contract to generate a function invocation sequence for the function to be tested through a backtracking algorithm on state variables. Then the arguments of transactions to invoke each function in the sequence are generated through regex matching to form the primitive test case. In the second step, the primitive test cases constitute an initial population, and a genetic algorithm undertakes the task of evolving them to high branch coverage. The experimental results on one of the VeriSmart datasets show that SV-Gen can effectively enter the control constraints related to state variables and improve the branch coverage of smart contracts.