Added support for third party packages on httptest package with tests & example. (#1992)

* Added support for third party packages on httptest package with tests.

* Update httptest.go

Co-authored-by: Gerasimos (Makis) Maropoulos <kataras2006@hotmail.com>

_examples/testing/ginkgotest/main.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"github.com/kataras/iris/v12"
+	"github.com/kataras/iris/v12/middleware/basicauth"
+)
+
+func newApp() *iris.Application {
+	app := iris.New()
+
+	opts := basicauth.Options{
+		Allow: basicauth.AllowUsers(map[string]string{"myusername": "mypassword"}),
+	}
+
+	authentication := basicauth.New(opts) // or just: basicauth.Default(map...)
+
+	app.Get("/", func(ctx iris.Context) { ctx.Redirect("/admin") })
+
+	// to party
+
+	needAuth := app.Party("/admin", authentication)
+	{
+		//http://localhost:8080/admin
+		needAuth.Get("/", h)
+		// http://localhost:8080/admin/profile
+		needAuth.Get("/profile", h)
+
+		// http://localhost:8080/admin/settings
+		needAuth.Get("/settings", h)
+	}
+
+	return app
+}
+
+func h(ctx iris.Context) {
+	username, password, _ := ctx.Request().BasicAuth()
+	// third parameter it will be always true because the middleware
+	// makes sure for that, otherwise this handler will not be executed.
+	// OR:
+	//
+	// user := ctx.User().(*myUserType)
+	// ctx.Writef("%s %s:%s", ctx.Path(), user.Username, user.Password)
+	// OR if you don't have registered custom User structs:
+	//
+	// ctx.User().GetUsername()
+	// ctx.User().GetPassword()
+	ctx.Writef("%s %s:%s", ctx.Path(), username, password)
+}
+
+func main() {
+	app := newApp()
+	app.Listen(":8080")
+}