CODEWITHSUNDEEP
go
Pierre
Pierre

Reputation: 630

go vet warns that example refers to unknown identifier, but why?

I have an Extractor interface that has a Playlist method:

// extractor.go
package extractor
type Extractor interface {
    Playlist(timestampFrom int64) (playlist.Tracklist, error)
}

I'm using this interface in another package:

// fip.go
package fip
type Extractor struct {
}

func (extractor Extractor) Playlist(timestampFrom int64) ([]playlist.Track, error) {
    // ...
}

And in my tests, I'd like to show an example on how to use the Playlist method for the fip package:

// fip_test.go
package fip
func ExamplePlaylist() { 
    // ...
}

But go vet shows this error: fip/extractor_test.go:82:1: ExamplePlaylist refers to unknown identifier: Playlist

I don't understand why... Playlist does exist as a method in the fip package. What am I missing?

If more context is needed, see these files with the full source:

https://github.com/coaxial/tizinger/blob/8016d52a1278cf44dde13d518c6a15a18cb29774/extractor/extractor.go

https://github.com/coaxial/tizinger/blob/8016d52a1278cf44dde13d518c6a15a18cb29774/fip/fip.go

https://github.com/coaxial/tizinger/blob/8016d52a1278cf44dde13d518c6a15a18cb29774/fip/fip_test.go

Upvotes: 4

Views: 1699

Answers (1)

Marc
Marc

Reputation: 21095

The correct name for the example function is ExampleExtractor_Playlist as described in the examples section of the testing docs.

Quoting:

The naming convention to declare examples for the package, a function F, a type T and method M on type T are:

func Example() { ... }
func ExampleF() { ... }
func ExampleT() { ... }
func ExampleT_M() { ... }

Your example is the last case where T is Extractor and M is Playlist.

Upvotes: 8

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