[Appraisals](https://github.com/thoughtbot/appraisal) is a tool to generate different `Gemfiles` so you can do matrix testing (e.g. different versions of ruby).
## How to add `appraisal` to your project
1. Add the `appraisal` to the group `development` from the Gemfile
```shell
bundle add appraisal --skip-install --group development
```
2. Run `bundle install` to install the dependencies.
```shell
bundle install
```
3. Create a `Appraisals` file on root of the project.
{…