We have several single method interfaces in expect.go:

• RequestFactory
• Client
• WebsocketDialer
• Reporter
• Logger

It would be convenient to provide an implementation for each of them similar to http.HandlerFunc, so that the user does not need to create a struct in sample cases.

For example, for Reporter we can provide ReporterFunc that is a wrapper for func (message string, args ...interface{}).

We can place each implementation right after corresponding interface in expect.go. Each one should have a documentation comment with code example that demonstrates how to use it with WithConfig. Each one also should be covered by unit test.