We use counterfeiter to generate mocks.
For example, token/driver/mock contains mock auto-generated files for the Driver API..
The generation directives can be found close to the interface that needs to be mocked, for example at token/driver/transfer.go:
//go:generate counterfeiter -o mock/ts.go -fake-name TransferService . TransferService
To regenerate all mock files, go to token/driver and run go generate.
The same applies to other packages containing the //go:generate directive.