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Change the order how middlewares are prepared for the request #28

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24 changes: 17 additions & 7 deletions controller_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -12,26 +12,32 @@ func Test_BaseController(t *testing.T) {
type testCase struct {
title string
method string
mws []Middleware
mws []func(w http.ResponseWriter) func (http.Handler) http.Handler
out string
}

cases := []testCase{
{
title: "register middleware for HTTP method",
method: http.MethodGet,
mws: []Middleware{middlewareOne},
out: "/mw1 before next/final handler/mw1 after next",
mws: []func(w http.ResponseWriter) func(http.Handler) http.Handler{
middlewareOne,
},
out: "/mw1 prepare/mw1 before next/final handler/mw1 after next",
},
{
title: "add middleware to existing chain",
method: http.MethodGet,
mws: []Middleware{middlewareTwo, middlewareThree},
out: "/mw1 before next/mw2 before next/mw3 before next/final handler/mw3 after next/mw2 after next/mw1 after next",
mws: []func(w http.ResponseWriter) func(http.Handler) http.Handler{
middlewareTwo, middlewareThree,
},
out: "/mw2 prepare/mw3 prepare/mw1 before next/mw2 before next/mw3 before next/final handler" +
"/mw3 after next/mw2 after next/mw1 after next",
},
{
title: "get an empty middleware chain (by default)",
method: http.MethodPost,
mws: []func(w http.ResponseWriter) func(http.Handler) http.Handler{},
out: "/final handler",
},
}
Expand All @@ -40,10 +46,14 @@ func Test_BaseController(t *testing.T) {
controller := NewBaseController()
for _, tc := range cases {
t.Run(tc.title, func(t *testing.T) {
w := httptest.NewRecorder()
if len(tc.mws) > 0 {
controller.AddMiddleware(tc.method, tc.mws...)
var mws []Middleware
for _, mw := range tc.mws {
mws = append(mws, mw(w))
}
controller.AddMiddleware(tc.method, mws...)
}
w := httptest.NewRecorder()
controller.Middleware(tc.method).Then(handlerFinal).ServeHTTP(w, nil)
if w.Body.String() != tc.out {
t.Errorf("handler output is expected to be %q but was %q", tc.out, w.Body.String())
Expand Down
7 changes: 6 additions & 1 deletion middleware.go
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Original file line number Diff line number Diff line change
Expand Up @@ -38,7 +38,12 @@ func (mw Middleware) Use(middlewares ...Middleware) Middleware {
for _, next := range middlewares {
mw = func(curr, next Middleware) Middleware {
return func(handler http.Handler) http.Handler {
return curr(next(handler))
var nextHandler http.Handler
currHandler := curr(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
nextHandler.ServeHTTP(w, r)
}))
nextHandler = next(handler)
return currHandler
}
}(mw, next)
}
Expand Down
149 changes: 91 additions & 58 deletions middleware_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -7,28 +7,37 @@ import (
)

var (
middlewareOne = func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("/mw1 before next"))
next.ServeHTTP(w, r)
w.Write([]byte("/mw1 after next"))
})
middlewareOne = func(w http.ResponseWriter) func (http.Handler) http.Handler {
w.Write([]byte("/mw1 prepare"))
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("/mw1 before next"))
next.ServeHTTP(w, r)
w.Write([]byte("/mw1 after next"))
})
}
}

middlewareTwo = func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("/mw2 before next"))
next.ServeHTTP(w, r)
w.Write([]byte("/mw2 after next"))
})
middlewareTwo = func(w http.ResponseWriter) func (http.Handler) http.Handler {
w.Write([]byte("/mw2 prepare"))
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("/mw2 before next"))
next.ServeHTTP(w, r)
w.Write([]byte("/mw2 after next"))
})
}
}

middlewareThree = func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("/mw3 before next"))
next.ServeHTTP(w, r)
w.Write([]byte("/mw3 after next"))
})
middlewareThree = func(w http.ResponseWriter) func (http.Handler) http.Handler {
w.Write([]byte("/mw3 prepare"))
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("/mw3 before next"))
next.ServeHTTP(w, r)
w.Write([]byte("/mw3 after next"))
})
}
}

middlewareFuncOne = func(w http.ResponseWriter, r *http.Request, next http.Handler) {
Expand All @@ -43,10 +52,13 @@ var (
w.Write([]byte("/mw func2 after next"))
}

middlewareBreak Middleware = func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("/skip the rest"))
})
middlewareBreak = func(w http.ResponseWriter) Middleware {
w.Write([]byte("/skip the rest prepare"))
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("/skip the rest"))
})
}
}

handlerOne = func(w http.ResponseWriter, r *http.Request) {
Expand All @@ -65,37 +77,48 @@ var (
func Test_Middleware(t *testing.T) {
type testCase struct {
title string
handler http.Handler
handler func (w http.ResponseWriter) http.Handler
out string
}

cases := []testCase{
{
title: "build handler with single middleware (one call of Use() func with single argument)",
handler: New().Use(middlewareOne).Then(handlerFinal),
out: "/mw1 before next/final handler/mw1 after next",
handler: func(w http.ResponseWriter) http.Handler {
return New().Use(middlewareOne(w)).Then(handlerFinal)
},
out: "/mw1 prepare/mw1 before next/final handler/mw1 after next",
},
{
title: "build handler passing middleware to the constructor (call New() with arguments)",
handler: New(middlewareOne, middlewareTwo).Use(middlewareThree).Then(handlerFinal),
out: "/mw1 before next/mw2 before next/mw3 before next/final handler/mw3 after next/mw2 after next/mw1 after next",
handler: func(w http.ResponseWriter) http.Handler {
return New(middlewareOne(w), middlewareTwo(w)).Use(middlewareThree(w)).Then(handlerFinal)
},
out: "/mw1 prepare/mw2 prepare/mw3 prepare/mw1 before next/mw2 before next/mw3 before next" +
"/final handler/mw3 after next/mw2 after next/mw1 after next",
},
{
title: "build handler with multiple middleware (adding one middleware per Use())",
handler: New().Use(middlewareOne).Use(middlewareTwo).Use(middlewareThree).Then(handlerFinal),
out: "/mw1 before next/mw2 before next/mw3 before next/final handler/mw3 after next/mw2 after next/mw1 after next",
handler: func(w http.ResponseWriter) http.Handler {
return New().Use(middlewareOne(w)).Use(middlewareTwo(w)).Use(middlewareThree(w)).Then(handlerFinal)
},
out: "/mw1 prepare/mw2 prepare/mw3 prepare/mw1 before next/mw2 before next/mw3 before next" +
"/final handler/mw3 after next/mw2 after next/mw1 after next",
},
{
title: "build handler with combination of single/plural calls of Use()",
handler: New().Use(middlewareOne).Use(middlewareTwo, middlewareThree).Then(handlerFinal),
out: "/mw1 before next/mw2 before next/mw3 before next/final handler/mw3 after next/mw2 after next/mw1 after next",
handler: func(w http.ResponseWriter) http.Handler {
return New().Use(middlewareOne(w)).Use(middlewareTwo(w), middlewareThree(w)).Then(handlerFinal)
},
out: "/mw1 prepare/mw2 prepare/mw3 prepare/mw1 before next/mw2 before next/mw3 before next" +
"/final handler/mw3 after next/mw2 after next/mw1 after next",
},
}

for _, tc := range cases {
t.Run(tc.title, func(t *testing.T) {
w := httptest.NewRecorder()
tc.handler.ServeHTTP(w, nil)
tc.handler(w).ServeHTTP(w, nil)
if w.Body.String() != tc.out {
t.Errorf("the output %q is expected to be %q", w.Body.String(), tc.out)
}
Expand All @@ -111,52 +134,62 @@ func Test_Chain(t *testing.T) {

type testCase struct {
title string
args []interface{}
args func (http.ResponseWriter) []interface{}
out string
panic bool
}

cases := []testCase{
{
title: "building handler with unsupported argument types should panic",
args: []interface{}{
middlewareOne,
middlewareTwo,
true,
middlewareThree,
handlerFinal,
args: func(w http.ResponseWriter) []interface{} {
return []interface{}{
middlewareOne(w),
middlewareTwo(w),
true,
middlewareThree(w),
handlerFinal,
}
},
panic: true,
},
{
title: "middleware should have control over the \"next\" handlers",
args: []interface{}{
middlewareOne,
middlewareTwo,
middlewareBreak,
middlewareThree,
handlerFinal,
args: func(w http.ResponseWriter) []interface{} {
return []interface{}{
middlewareOne(w),
middlewareTwo(w),
middlewareBreak(w),
middlewareThree(w),
handlerFinal,
}
},
out: "/mw1 before next/mw2 before next/skip the rest/mw2 after next/mw1 after next",
out: "/mw1 prepare/mw2 prepare/skip the rest prepare/mw3 prepare/mw1 before next/mw2 before next" +
"/skip the rest/mw2 after next/mw1 after next",
},
{
title: "calling function without any arguments should build a middleware with only blobHandler",
args: func(w http.ResponseWriter) []interface{} {
return []interface{}{}
},
out: "/blob handler",
},
{
title: "building handler with all kind of supported arguments should be successful",
args: []interface{}{
middlewareOne,
Middleware(middlewareTwo),
middlewareFuncOne,
MiddlewareFunc(middlewareFuncTwo),
handlerOne,
http.HandlerFunc(handlerTwo),
middlewareThree,
handlerFinal,
args: func(w http.ResponseWriter) []interface{} {
return []interface{}{
middlewareOne(w),
Middleware(middlewareTwo(w)),
middlewareFuncOne,
MiddlewareFunc(middlewareFuncTwo),
handlerOne,
http.HandlerFunc(handlerTwo),
middlewareThree(w),
handlerFinal,
}
},
out: "/mw1 before next/mw2 before next/mw func1 before next/mw func2 before next" +
"/first handler/second handler/mw3 before next/final handler/blob handler" +
out: "/mw1 prepare/mw2 prepare/mw3 prepare/mw1 before next/mw2 before next/mw func1 before next" +
"/mw func2 before next/first handler/second handler/mw3 before next/final handler/blob handler" +
"/mw3 after next/mw func2 after next/mw func1 after next/mw2 after next/mw1 after next",
},
}
Expand All @@ -175,7 +208,7 @@ func Test_Chain(t *testing.T) {
}
}()
w := httptest.NewRecorder()
Chain(tc.args...).ServeHTTP(w, nil)
Chain(tc.args(w)...).ServeHTTP(w, nil)
if w.Body.String() != tc.out {
t.Errorf("out %v expected to be %v", w.Body.String(), tc.out)
}
Expand Down