⚠️ Code now lives in https://gitlab.com/prytoegrian/check-break

Check-break

check-break helps you to discover compatibility breaks in your code, and to improve decisions-making to determine if a new major version is required. In few words, if you follow semver (or try to stick to it), you must use check-break ;-)

check-break itself follows semver and monitors its own changes. For now, it's under heavy development, use it at your own risks, compatibility breaks could happen at every moment.

What is a compatibility break ?

Basically, following the semver definition :

A change is incompatible if it removes a possibility for the consumer in the public API.

All starts with a clear definition of public API in your context. Once done, a compatibility break occurs on all public API functions each time :

• a function is removed
• an argument is removed
• an argument is added (without a default value)
• a default argument is removed
• a default value is changed
• a return type is removed
• a return type is added
• type of any input / output / exception / assertion is changed and is incompatible with the former one (1)

1. In other words, if you're comfortable with Liskov principle, you might have heard :

Be contravariant in your preconditions, be covariant with your postconditions.

Thus, a compatibility break happens when you're covariant in your preconditions or contravariant in your postconditions.

Since check-break can't guess your public API (yet), it shows you all changes on public functions. It's up to you to determine if :

• this change really is a break,
• this change is in the public API scope.

First launch

(Assuming there's a golang env on your system)

make install

That's it.

Usage

This tool is based upon git, and particularly on diff between two points. Thus, the syntax is as follows :

$ check-break -s starting_point -e ending_point [-p path_to_git_repository] [-c path_to_config_file]

Note: All unsupported files are also reported as such, in order not to give a feeling of false negative.

Langages supported

Obviously, I started with langages I use in a daily-basis :

• Go
• Java
• Javascript
• PHP
• sh

Feel free to participate to add yours, correct bugs, improve design, etc. check-break is under GPL3.

Please remember that this tool may be incomplete, it doesn't replace the human judgment.