When testing a model that calls other models, you can use mock models to generate predictable output. Mock models are simply configured static model outputs for a specified model slug (and optionally some partial input properties to match.)
For example, if you’re developing a model that queries some data (by calling a ledger model for example) and then does some processing on it, you can mock the ledger model to return a set of test data.
Please follow the in-depth description to set up the mocks here.