mockery provides the ability to easily generate mocks for golang interfaces. It removes the boilerplate coding required to use mocks.

go get github.com/vektra/mockery, then $GOPATH/bin/mockery

Given this is in string.go

package test

type Stringer interface {
  String() string
}

Run: mockery -name=Stringer and the following will be output to mocks/Stringer.go:

package mocks

import "github.com/stretchr/testify/mock"

type Stringer struct {
 mock.Mock
}

func (m *Stringer) String() string {
 ret := m.Called()

 r0 := ret.Get(0).(string)

 return r0
}

mockery pulls in all the same imports used in the file that contains the interface so that package types will work correctly. It then runs the output through the imports package to remove any unnecessary imports (as they'd result in compile errors).

mockery should handle all types. If you find it does not, please report the issue.

It's common for a big package to have a lot of interfaces, so mockery provides -all. This option will tell mockery to scan all files under the directory named by -dir ("." by default) and generates mocks for any interfaces it finds.

-all was designed to be able to be used automatically in the background if required.

mockery always generates files with the package mocks to keep things clean and simple. You can control which mocks directory is used by using -output, which defaults to ./mocks.

Use mockery -print to have the resulting code printed out instead of written to disk.

When your interfaces are in the main package you should supply the -inpkg flag. This will generate mocks in the same package as the target code avoiding import issues.