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eth-mutants

eth-mutants is a mutation testing tool for Solidity contracts.

What is mutation testing?

It about performing changes to your code (like replacing a < for a <=) and running your tests. If they pass we say that the mutation lived/survived, which means that you werent checking the condition and you should ensure there is a test case covering it.

It's a great companion to existing test coverage tools, ensuring that you are not only running every line, but actually asserting logic about the control flow around them.

For more information, check out the Wikipedia page on mutation testing.

Installation

npm install eth-mutants

Usage

The `preflight` command will show the number of possible mutations found
and print some compact diffs for each mutation. Use this to understand
how long it may take to visit all mutations and please report any invalid 
ones.

The test command will start applying mutations and running your tests to check if they pass. It will report the result of each mutation.

eth-mutants test

This tools makes some important assumptions about your workspace, which should hold true for most Truffle-based projects, but I plan on adding options to override them soon:

• Your contract files are in the contracts/ directory
• You run your tests with npm test which returns a non-zero error code in case of failure.

Mutators

The only mutation implemented at the moment is called boundary-condition and replaces < and > for <= and >= and vice-versa. Contributions for mutators are especially welcomed.

Prior Art

• PIT is a mutation testing tool for Java with a long track record.
• mutmut is a mutation testing tool for Python.

Author

Federico Bond

License

MIT