Mocking the `HttpApiClient` in the Effect Typescript library can be done by creating a mock imple...

class TestApiGroup extends HttpApiGroup.make('test').add(
  HttpApiEndpoint.get('hi', '/hello').addSuccess(S.String),
) {}

class TestApi extends HttpApi.make('test').add(TestApiGroup) {}

class ClientLive extends Effect.Service<ClientLive>()('ClientLive', {
  effect: HttpApiClient.make(TestApi),
}) {}

const mockClient = ClientLive.make({
  test: {
    hi: () => Effect.succeed('hello'),
  },
});