glogrus does not implement http.Flusher even if the underlying http.ResponseWriter does

[bsdlp]

consider the following test code (mostly copied from this repo's README)

package main

import (
    "fmt"
    "log"
    "net/http"

    "goji.io/pat"

    goji "goji.io"

    "golang.org/x/net/context"

    "github.com/Sirupsen/logrus"
    glogrus "github.com/goji/glogrus2"
)

func a(ctx context.Context, w http.ResponseWriter, r *http.Request) {
    _, ok := w.(http.Flusher)
    fmt.Fprintln(w, ok)
}

func main() {
    broken := goji.NewMux()
    logr := logrus.New()
    logr.Formatter = new(logrus.JSONFormatter)
    broken.UseC(glogrus.NewGlogrus(logr, "my-app-name"))

    broken.HandleFuncC(pat.Get("/"), a)

    working := goji.NewMux()
    working.HandleFuncC(pat.Get("/"), a)

    go func() {
        http.ListenAndServe(":8081", working)
    }()
    log.Fatal(http.ListenAndServe(":8080", broken))
}

the results:

jchen@locke-(master|✔)> curl http://localhost:8081/
true
jchen@locke-(master|✔)> curl http://localhost:8080/
false

Also check out this example which seemingly proves that a struct that embeds an interface cannot be type asserted to another interface that the struct itself doesn't implement even if the embedded struct implements the second interface.

Proposal:

type assert the http.ResponseWriter in wrapWriter and use a new struct that implements http.Flusher, http.CloseNotifierand http.Hijacker if the ResponseWriter does. Similar to this perhaps?