Golang monkey patching
When I have run into this situation my approach is to use my own interface as a wrapper which allows mocking in tests. For example.
type MyInterface interface {
DoSomething(i int) error
DoSomethingElse() ([]int, error)
}
type Concrete struct {
client *somepackage.Client
}
func (c *Concrete) DoSomething(i int) error {
return c.client.DoSomething(i)
}
func (c *Concrete) DoSomethingElse() ([]int, error) {
return c.client.DoSomethingElse()
}
Now you can mock the Concrete in the same way you would mock somepackage.Client
if it too were an interface.
As pointed out in the comments below by @elithrar, you can embed the type you want to mock so you are only forced to add methods which need mocking. For example:
type Concrete struct {
*somepackage.Client
}
When done like that, additional methods like DoSomethingNotNeedingMocking
could be called directly on Concrete
without having to add it to the interface / mock it out.
There is an available monkey patching library for Go. It only works for Intel/AMD systems (targeting OSX and Ubuntu in particular).