102 lines
2.4 KiB
Markdown
102 lines
2.4 KiB
Markdown
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Interface mocking tool for go generate.
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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).
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### What is Moq?
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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.
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### Installing
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To start using Moq, just run go get:
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```
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$ go get github.com/matryer/moq
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```
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### Usage
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```
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moq [flags] destination interface [interface2 [interface3 [...]]]
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-out string
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output file (default stdout)
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-pkg string
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package name (default will infer)
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```
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In a command line:
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```
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$ moq -out mocks_test.go . MyInterface
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```
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In code (for go generate):
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```go
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package my
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//go:generate moq -out myinterface_moq_test.go . MyInterface
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type MyInterface interface {
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Method1() error
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Method2(i int)
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}
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```
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Then run `go generate` for your package.
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### How to use it
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Mocking interfaces is a nice way to write unit tests where you can easily control the behaviour of the mocked object.
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Moq creates a struct that has a function field for each method, which you can declare in your test code.
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This this example, Moq generated the `EmailSenderMock` type:
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```go
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func TestCompleteSignup(t *testing.T) {
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called := false
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var sentTo string
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mockedEmailSender = &EmailSenderMock{
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SendFunc: func(to, subject, body string) error {
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called = true
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sentTo = to
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return nil
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},
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}
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CompleteSignUp("me@email.com", mockedEmailSender)
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if called == false {
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t.Error("Sender.Send expected")
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}
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if sentTo != "me@email.com" {
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t.Errorf("unexpected recipient: %s", sentTo)
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}
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}
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func CompleteSignUp(to string, sender EmailSender) {
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// TODO: this
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}
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```
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The mocked structure implements the interface, where each method calls the associated function field.
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## Tips
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* Keep mocked logic inside the test that is using it
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* Only mock the fields you need - it will panic if a nil function gets called
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* Use closured variables inside your test function to capture details about the calls to the methods
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* Use `go:generate` to invoke the `moq` command
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## License
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The Moq project (and all code) is licensed under the [MIT License](LICENSE).
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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/).
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