Fake

Fake is a Go type-safe mocking generator. It automatically creates type-safe mocks for any public interface.

Features

Type-safe mock generation
Support for generics
Granular mock generation
Mock cache for ultra-fast mock regeneration
Function call configuration, with Repeatability and Optional calls
Automatic call assertion
Caching, only regenerate updated interfaces
Automatic cleanup of generated mocks from removed code

Installation

Go install

Make sure $GO_PATH/bin is in your $PATH

go install github.com/sonalys/fake/entrypoint/fake@latest

Release download

Visit the Release Page and download the correct binary for your architecture/os.

Docker

You can safely run fake from a docker container using

docker run --rm -u $(id -u):$(id -g) -v .:/code ghcr.io/sonalys/fake:latest /fake -input /code -output /code/mocks

Usage


Usage:

  fake -input PATH -output mocks -ignore tests

The flags are:

  FLAG          TYPE      DEFAULT   DESCRIPTION
  -input        []STRING  .         Folder to scan for interfaces, can be invoked multiple times
  -output       STRING    mocks     Output folder, it will follow a tree structure repeating the package path
  -ignore       []STRING            Folder to ignore, can be invoked multiple times
  -interface    []STRING            Usually used with go:generate for granular mock generation for specific interfaces
  -mockPackage  STRING    mocks     Used with -interface. Specify the package name of the generated mock

Examples

A very simple example would be:

type UserDB interface {
	Login(userID string) error
}

Will generate the following mock:

type UserDB interface {
	Login(userID string) error
}
type StubInterface struct {
	setupLogin      mockSetup.Mock[func(userID string) error]
}

func (s *StubInterface[T]) OnLogin(funcs ...func(userID string) error) Config
func (s *StubInterface[T]) Login(userID string) error
...

Granular generation with go generate:

//go:generate fake -interface Reader
type Reader interface {
	io.Reader
}
// or
//go:generate go run github.com/sonalys/fake/entrypoint/fake -interface Reader
type Reader interface {
	io.Reader
}

Example usage for tests

func Test_Stub(t *testing.T) {
  mock := mocks.NewUserDB(t) // Setup call expectations
  config := mock.OnLogin(func(userID string) error {
    require.NotEmpty(t, userID)
    return nil
  })
  // Here you can configure it with:
  config.Repeat(1) // Repeat 1 is default behavior.
  // or with .Maybe(), which won't fail tests it not called.
  config.Maybe()

  var userDB UserDB = mock
  userDB.Login("userID") // Will call the previous function.
}

Contributors

Any issues or improvements discussions are welcome! Feel free to contribute. Thank you for your collaboration!