[ALT] Overriding app.ErrorMiddleware has no effect fixes #1466 (#1564)

app.go

@@ -16,15 +16,14 @@ import (
 type App struct {
 	Options
 	// Middleware returns the current MiddlewareStack for the App/Group.
-	Middleware      *MiddlewareStack `json:"-"`
-	ErrorHandlers   ErrorHandlers    `json:"-"`
-	ErrorMiddleware MiddlewareFunc   `json:"-"`
-	router          *mux.Router
-	moot            *sync.RWMutex
-	routes          RouteList
-	root            *App
-	children        []*App
-	filepaths       []string
+	Middleware    *MiddlewareStack `json:"-"`
+	ErrorHandlers ErrorHandlers    `json:"-"`
+	router        *mux.Router
+	moot          *sync.RWMutex
+	routes        RouteList
+	root          *App
+	children      []*App
+	filepaths     []string
 }
 
 // Muxer returns the underlying mux router to allow
@@ -52,9 +51,6 @@ func New(opts Options) *App {
 	}
 
 	dem := a.defaultErrorMiddleware
-	if a.ErrorMiddleware != nil {
-		dem = a.ErrorMiddleware
-	}
 	a.Middleware = newMiddlewareStack(dem)
 
 	notFoundHandler := func(errorf string, code int) http.HandlerFunc {

errors.go

@@ -49,9 +49,20 @@ func (e ErrorHandlers) Get(status int) ErrorHandler {
 	if eh, ok := e[status]; ok {
 		return eh
 	}
+	if eh, ok := e[0]; ok {
+		return eh
+	}
 	return defaultErrorHandler
 }
 
+// Default sets an error handler should a status
+// code not already be mapped. This will replace
+// the original default error handler.
+// This is a *catch-all* handler.
+func (e ErrorHandlers) Default(eh ErrorHandler) {
+	e[0] = eh
+}
+
 // PanicHandler recovers from panics gracefully and calls
 // the error handling code for a 500 error.
 func (a *App) PanicHandler(next Handler) Handler {

errors_test.go

@@ -122,3 +122,22 @@ func Test_defaultErrorMiddleware(t *testing.T) {
 	r.True(ok)
 	r.Equal("t", x)
 }
+
+func Test_SetErrorMiddleware(t *testing.T) {
+	r := require.New(t)
+	app := New(Options{})
+	app.ErrorHandlers.Default(func(code int, err error, c Context) error {
+		res := c.Response()
+		res.WriteHeader(418)
+		res.Write([]byte("i'm a teapot"))
+		return nil
+	})
+	app.GET("/", func(c Context) error {
+		return c.Error(422, errors.New("boom"))
+	})
+
+	w := httptest.New(app)
+	res := w.HTML("/").Get()
+	r.Equal(418, res.Code)
+	r.Equal("i'm a teapot", res.Body.String())
+}

go.mod

@@ -43,6 +43,6 @@ require (
 	github.com/stretchr/testify v1.3.0
 	golang.org/x/crypto v0.0.0-20190131182504-b8fe1690c613
 	golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4
-	golang.org/x/tools v0.0.0-20190201185910-0e05534988fe
+	golang.org/x/tools v0.0.0-20190202235157-7414d4c1f71c
 	gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc
 )

go.sum

@@ -583,8 +583,8 @@ golang.org/x/tools v0.0.0-20190118193359-16909d206f00/go.mod h1:n7NCudcB/nEzxVGm
 golang.org/x/tools v0.0.0-20190122202912-9c309ee22fab/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190124004107-78ee07aa9465/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190131142011-8dbcc66f33bb/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
-golang.org/x/tools v0.0.0-20190201185910-0e05534988fe h1:vnIBlz9Fwms9Qgql2K0Ar+XatQxNe3xuRwzm4XtKZJ8=
-golang.org/x/tools v0.0.0-20190201185910-0e05534988fe/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20190202235157-7414d4c1f71c h1:6Axm8Kqba7gHaI7My7snFynbKaVEYko0z35GPOJygUA=
+golang.org/x/tools v0.0.0-20190202235157-7414d4c1f71c/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 google.golang.org/appengine v1.2.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
 google.golang.org/appengine v1.3.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
 google.golang.org/appengine v1.4.0 h1:/wp5JvzpHIxhs/dumFmF7BXTf3Z+dd4uXta4kVyO508=

route_info.go

@@ -109,10 +109,14 @@ func (ri RouteInfo) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 	err := a.Middleware.handler(ri)(c)
 
 	if err != nil {
+		status := 500
+		if he, ok := err.(HTTPError); ok {
+			status = he.Status
+		}
 		events.EmitError(EvtRouteErr, err, payload)
 		// things have really hit the fan if we're here!!
 		a.Logger.Error(err)
-		c.Response().WriteHeader(500)
+		c.Response().WriteHeader(status)
 		c.Response().Write([]byte(err.Error()))
 	}
 	events.EmitPayload(EvtRouteFinished, payload)