How to test my microservices before deploy to kubernetes?

I am creating a very small microservices environment for testing purpose. It looks as follows:

As you can see on the image, Istio is installed in the k8s cluster to use service mesh.

I wrote the BOO service, but do not know how to test the service, because it calls FOO and ZOO services.

I could mock FOO and ZOO services but when in the future the BOO services calls 10 further services, then it does make any sense then to mock all services.

What the best way to test my microservices before deploy to kubernetes?