Announcing Stryker 100% mode

Nico Jansen

Nico Jansen

Stryker Team

Over the years, we've been privileged to explain the concept of Mutation Testing to great developers, testers and others. The concept of inserting bugs into your production code in order to test your tests sparks the imagination.

But when people start using mutation testing in practice, they quickly realize that things are not as easy as they seem. One of the most common questions is: "what 'mutation score' is good enough"? Our general advice is not to strive for 100%. But should you use 80%? Or some other percentage? Some users just want to see that everything is great with their tests.

That's why we're introducing a new '100%' mode! With this mode, Stryker itself will strive to improve your mutation score to be 100%. You can activate it with the --100 command line flag, but we're thinking of making this the default mode.

๐Ÿ™‰ An example

A picture says more than a thousand words. First without the new --100 mode:

![]9/images/blogs/stryker-without-100-mode.png)

And now with the new --100 mode:

As you can see, this new mode makes for a far better-looking report!

And things just keep getting better. Since all mutants will be killed - no matter what, you'll not have to wait long, because Stryker can internally optimize the process to not do actual testing whatsoever. A huge performance gain!

๐Ÿ”ฎ What's next?

Seeing as this is such an obvious improvement, it will not take long for other mutation testing frameworks to follow suit. That's why it's only a matter of time before the legendary Mull, InfectionPHP and Pitest will have this new and very important feature.

Don't hesitate to open an issue if this important mode is missing.