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
}

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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.
}

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Contributors

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

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