grafana/pkg/web/webtest/middleware.go
sh0rez 534ece064b
pkg/web: closure-style middlewares (#51238)
* pkg/web: closure-style middlewares

Switches the middleware execution model from web.Handlers in a slice to
web.Middleware.
Middlewares are temporarily kept in a slice to preserve ordering, but
prior to execution they are applied, forming a giant call-stack, giving
granular control over the execution flow.

* pkg/middleware: adapt to web.Middleware

* pkg/middleware/recovery: use c.Req over req

c.Req gets updated by future handlers, while req stays static.

The current recovery implementation needs this newer information

* pkg/web: correct middleware ordering

* pkg/webtest: adapt middleware

* pkg/web/hack: set w and r onto web.Context

By adopting std middlewares, it may happen they invoke next(w,r) without
putting their modified w,r into the web.Context, leading old-style
handlers to operate on outdated fields.

pkg/web now takes care of this

* pkg/middleware: selectively use future context

* pkg/web: accept closure-style on Use()

* webtest: Middleware testing

adds a utility function to web/webtest to obtain a http.ResponseWriter,
http.Request and http.Handler the same as a middleware that runs would receive

* *: cleanup

* pkg/web: don't wrap Middleware from Router

* pkg/web: require chain to write response

* *: remove temp files

* webtest: don't require chain write

* *: cleanup
2022-08-09 14:58:50 +02:00

74 lines
1.9 KiB
Go

package webtest
import (
"net/http"
"net/http/httptest"
"github.com/grafana/grafana/pkg/web"
)
type Context struct {
Req *http.Request
Rw http.ResponseWriter
Next http.Handler
}
// Middleware is a utility for testing middlewares
type Middleware struct {
// Before are run ahead of the returned context
Before []web.Handler
// After are part of the http.Handler chain
After []web.Handler
// The actual handler at the end of the chain
Handler web.Handler
}
// MiddlewareContext returns a *http.Request, http.ResponseWriter and http.Handler
// exactly as if it was passed to a middleware
func MiddlewareContext(test Middleware, req *http.Request) *Context {
m := web.New()
// pkg/web requires the chain to write an HTTP response.
// While this ensures a basic amount of correctness for real handler chains,
// it is naturally incompatible with this package, as we terminate the chain early to pass its
// state to the surrounding test.
// By replacing the http.ResponseWriter and writing to the old one we make pkg/web happy.
m.Use(func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusOK)
rw := web.Rw(httptest.NewRecorder(), r)
next.ServeHTTP(rw, r)
})
})
for _, mw := range test.Before {
m.Use(mw)
}
ch := make(chan *Context)
m.Use(func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
ch <- &Context{
Req: r,
Rw: w,
Next: next,
}
})
})
for _, mw := range test.After {
m.Use(mw)
}
// set the provided (or noop) handler to exactly the queried path
handler := test.Handler
if handler == nil {
handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {})
}
m.Handle(req.Method, req.URL.RequestURI(), []web.Handler{handler})
go m.ServeHTTP(httptest.NewRecorder(), req)
return <-ch
}