example | ||
generate | ||
package/moq | ||
.gitignore | ||
LICENSE | ||
main.go | ||
moq-logo-small.png | ||
moq-logo.png | ||
README.md |
Interface mocking tool for go generate.
By Mat Ryer and David Hernandez, with ideas lovingly stolen from Ernesto Jimenez.
What is moq?
Moq is a tool that generates a struct from any interface. The struct can be used in test code as a mock of the interface.
Usage
In a command line:
moq InterfaceName -out mocks_test.go
In code (for go generate):
package my
//go:generate moq MyInterface -out myinterface_moq_test.go
type MyInterface interface {
Method1() error
Method2(i int)
}
Then run go generate
for your package.
Install
go install github.com/matryer/moq
How to use it
Mocking interfaces is a nice way to write unit tests where you can easily control the behaviour of the mocked object.
Moq creates a struct that has a function field for each method, which you can declare in your test code.
This this example, Moq generated the EmailSenderMock
type:
func TestCompleteSignup(t *testing.T) {
called := false
var sentTo string
mockedEmailSender = &EmailSenderMock{
SendFunc: func(to, subject, body string) error {
called = true
sentTo = to
return nil
},
}
CompleteSignUp("me@email.com", mockedEmailSender)
if called == false {
t.Error("Sender.Send expected")
}
if sentTo != "me@email.com" {
t.Errorf("unexpected recipient: %s", sentTo)
}
}
func CompleteSignUp(to string, sender EmailSender) {
// TODO: this
}
The mocked structure implements the interface, where each method calls the associated function field.
Using go generate
At the top of the file containing the interface you wish to mock, you can use
go generate
to specify the interface to mock:
package test
//go:generate moq -out myface_test.go . MyFace
type MyFace interface {
Method() string
}
Then navigate to the directory in a shell, and run go generate
.
Tips
- Keep mocked logic inside the test that is using it
- Only mock the fields you need - it will panic if a nil function gets called
- Use closured variables inside your test function to capture details about the calls to the methods
- Use
go:generate
to invoke themoq
command
License
The moq command (and all code) is licensed under the MIT License.
The moq logo was created by Chris Ryer and is licensed under the Creative Commons Attribution 3.0 License.