fix #1446

Former-commit-id: 6ac95ef58bf3dd0dac8bed2100495fa9908f41d4

_examples/routing/conditional-chain/main.go

@@ -4,7 +4,7 @@ import (
 	"github.com/kataras/iris/v12"
 )
 
-func main() {
+func newApp() *iris.Application {
 	app := iris.New()
 	v1 := app.Party("/api/v1")
 
@@ -15,7 +15,8 @@ func main() {
 	}
 
 	onlyWhenFilter1 := func(ctx iris.Context) {
-		ctx.Application().Logger().Infof("admin: %s", ctx.Params())
+		ctx.Application().Logger().Infof("admin: %#+v", ctx.URLParams())
+		ctx.Writef("<title>Admin</title>\n")
 		ctx.Next()
 	}
 
@@ -43,6 +44,12 @@ func main() {
 		ctx.HTML("requested: <b>/api/v1/users</b>")
 	})
 
+	return app
+}
+
+func main() {
+	app := newApp()
+
 	// http://localhost:8080/api/v1/users
 	// http://localhost:8080/api/v1/users?admin=true
 	app.Run(iris.Addr(":8080"))

_examples/routing/conditional-chain/main_test.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/kataras/iris/v12/httptest"
+)
+
+func TestNewConditionalHandler(t *testing.T) {
+	app := newApp()
+	e := httptest.New(t, app)
+
+	e.GET("/api/v1/users").Expect().Status(httptest.StatusOK).
+		Body().Equal("requested: <b>/api/v1/users</b>")
+	e.GET("/api/v1/users").WithQuery("admin", "true").Expect().Status(httptest.StatusOK).
+		Body().Equal("<title>Admin</title>\n<h1>Hello Admin</h1><br>requested: <b>/api/v1/users</b>")
+}

context/handler.go

@@ -90,6 +90,7 @@ func NewConditionalHandler(filter Filter, handlers ...Handler) Handler {
 			// to check and modify the per-request handlers chain at runtime.
 			currIdx := ctx.HandlerIndex(-1)
 			currHandlers := ctx.Handlers()
+
 			if currIdx == len(currHandlers)-1 {
 				// if this is the last handler of the chain
 				// just add to the last the new handlers and call Next to fire those.
@@ -98,7 +99,7 @@ func NewConditionalHandler(filter Filter, handlers ...Handler) Handler {
 				return
 			}
 			// otherwise insert the new handlers in the middle of the current executed chain and the next chain.
-			newHandlers := append(currHandlers[:currIdx], append(handlers, currHandlers[currIdx+1:]...)...)
+			newHandlers := append(currHandlers[:currIdx+1], append(handlers, currHandlers[currIdx+1:]...)...)
 			ctx.SetHandlers(newHandlers)
 			ctx.Next()
 			return