White box testing

If you are unit testing your application you should stub all external services.

If you are using sttp client to send HTTP requests, and if the externals apis, which yours application consumes, are described using tapir, you can create a stub of the service by converting endpoints to SttpBackendStub (see the sttp documentation for details on how the stub works).

Add the dependency:

"com.softwaremill.sttp.tapir" %% "tapir-sttp-stub-server" % "0.15.4"

And the following import:

import sttp.tapir.server.stub._

Then, convert any endpoint to SttpBackendStub:

val endpoint = sttp.tapir.endpoint
  .in("api" / "sometest4")

implicit val backend = SttpBackendStub

Black box testing

When testing application as a whole component, running for example in docker, you might want to stub external services with which you application interacts, to steer their behaviors.

To do that you might want to use well-known solutions like e.g. wiremock or mock-server, but if their api is described using tapir you might want to use livestub, which combines nicely with the rest of the sttp ecosystem.