Hi @ztatman1 ,
Thanks for your post and welcome to the Cesium community.
There is a more detailed discussion on using Jest to test Cesium in this thread Testing Cesium in Jest - #10 by naftali123 with some additional information
on making use of getWebGLStub.js if you are testing in an environment without access to webGL, such as the command line.
Please let us know if that thread is not helpful and if you do so please include more details and sample code showing your use case.
Thanks,
Luke