Fettle is an experimental mutation testing tool for C#.

Right now Fettle can mutation-test your project if you use:

• .NET Framework 4.x
• NUnit framework 3.x (version 3.10 or higher recommended)

To start using Fettle, see the getting started guide.
To build from source, see the developer guide.

Fettle comes with some optimisations to make mutation testing faster:

• It will perform test impact analysis on your project to try and find the subset of tests to run for a given piece of source-code.
• It can be configured to only mutate your local changes rather than your entire code-base.

If you're having problems running Fettle see the troubleshooting guide.
If you're still having issues feel free to get in touch on the gitter page or create an issue.

There's also a list of supported mutations.

Fettle relies on some awesome .NET projects which include:

• Roslyn
• NUnit
• Paket
• FAKE

This is an experimental project run within comparethemarket / BGL Group. If you are stuck, or keen to help, then please get in touch on the gitter page or open an issue.

Note that we have a code of conduct.

Oli Wennell did the initial work and is the project's maintainer.
Here's a list of the lovely people that have helped the project by contributing.

This project is licensed under the MIT License - see the LICENSE file for details

Thanks to:

• The authors of the other mutation testing tools out there for inspiration.
• PurpleBooth for their README template.
• Contributor covenant for their code of conduct.