Make HTTP middleware easier to use

common/testing/prpctest/server.go

Index: common/testing/prpctest/server.go
diff --git a/common/testing/prpctest/server.go b/common/testing/prpctest/server.go
index 670482440596f82ba99e157f6af35790aee079a5..63cc4358505c6d251b47d630fec0e281f98a219d 100644
--- a/common/testing/prpctest/server.go
+++ b/common/testing/prpctest/server.go
@@ -12,11 +12,10 @@ import (
 	"net/http/httptest"
 	"net/url"
 
-	"github.com/julienschmidt/httprouter"
 	prpcCommon "github.com/luci/luci-go/common/prpc"
 	"github.com/luci/luci-go/server/auth"
-	"github.com/luci/luci-go/server/middleware"
 	"github.com/luci/luci-go/server/prpc"
+	"github.com/luci/luci-go/server/router"
 	"golang.org/x/net/context"
 )
 
@@ -25,8 +24,8 @@ type Server struct {
 	prpc.Server
 
 	// Base is the base middleware generator factory. It is handed the Context
-	// passed to Start. If nil, middleware.TestingBase will be used.
-	Base func(context.Context) middleware.Base
+	// passed to Start. If Base is nil, middleware.TestingBase will be used.
+	Base func(c context.Context) router.Base
 
 	// HTTP is the active HTTP test server. It will be valid when the Server is
 	// running.
@@ -42,11 +41,11 @@ func (s *Server) Start(c context.Context) {
 	s.Authenticator = auth.Authenticator{}
 	mwb := s.Base
 	if mwb == nil {
-		mwb = middleware.TestingBase
+		mwb = router.TestingBase
 	}
 
-	r := httprouter.New()
-	s.InstallHandlers(r, mwb(c))
+	r := router.New()
+	s.InstallHandlers(r, mwb(c)())
 	s.HTTP = httptest.NewServer(r)
 }