Mock Adapter User - https://medium.com/@covalentxHQ/convector-unit-test-identities-54903c5bfde4

controller.ts

// Create the mock controller adapter
const adapter = new MockControllerAdapter();
// Create the participant client
const participantCtrl = ClientFactory(ParticipantController, adapter);

// Initialize the adapter with all the controllers
await adapter.init([...]);

// Register an user
adapter.addUser('MyUser1');

// Create the participant model
const participantModel = new Participant({
  id: uuid(),
  name: 'Diego'
});

// Invoke a function using the corresponding username
await participantCtrl.$withUser('MyUser1').register(participantModel);

// Retrieve the participant from network
const savedModel = await Participant.getOne(participantModel.id);

// Compare the identity assigned in the controller using `this.sender`...
expect(savedModel.identity)
  // ... with the fingerprint of the mocked user
  .to.eq(adapter.getUserFingerprint('MyUser1'))