How to test a unexported (private) function in go (golang)?

create a test file within the package

library_test.go

package mypkg

func TestPrivateStruct(t *testing.T){
  pf := private{ "Private Field" }
  ....
}

library.go

package mypkg

type private struct {
  privateField string
}

go test mypkg -v will run your Tests with your private struct