Ruby inherit tests from gem

Context

I have a framework that I'm building where I'm separating out different parts into their own gems. I'm doing this for two reasons:

1. Make it easier for me to know what's going on in each one, and focus on just what's going on in the component
2. Make it so you can include only individual components and the minimum code required is loaded

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Question

I want to make sure my new components don't break old ones. How can I run tests from other gems? Is there a better way to solve this that I'm not thinking of?

Example:

Two components, one that deals with the file system, the other one with ftp via the file system. When I introduce ftp I don't want to break file system, and therefore want to run tests for both.