moq/README.md
2016-09-22 09:29:05 +01:00

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![moq logo](moq-logo-small.png)
Interface mocking tool for go generate.
By [Mat Ryer](https://twitter.com/matryer) and [David Hernandez](https://github.com/dahernan), with ideas lovingly stolen from [Ernesto Jimenez](https://github.com/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.
### Installing
To start using Moq, just run go get:
```
$ go get github.com/matryer/moq
```
### Usage
```
moq [flags] destination interface [interface2 [interface3 [...]]]
-out string
output file (default stdout)
-pkg string
package name (default will infer)
```
In a command line:
```
$ moq -out mocks_test.go . MyInterface
```
In code (for go generate):
```go
package my
//go:generate moq -out myinterface_moq_test.go . MyInterface
type MyInterface interface {
Method1() error
Method2(i int)
}
```
Then run `go generate` for your package.
### 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:
```go
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.
## 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 the `moq` command
## License
The Moq project (and all code) is licensed under the [MIT License](LICENSE).
The Moq logo was created by [Chris Ryer](http://chrisryer.co.uk) and is licensed under the [Creative Commons Attribution 3.0 License](https://creativecommons.org/licenses/by/3.0/).