Function Example_httpHandlerMiddleware

stack/example_test.go:190–228

Registers a middleware to trap exceptions and report them on http.Handler. For demonstration purposes, start a web server that panics and call into it.

()

// For demonstration purposes, start a web server that panics and call into
// it.
func Example_httpHandlerMiddleware() {
	// Start the web server.
	ln, err := net.Listen("tcp", "localhost:0")
	if err != nil {
		log.Fatal(err)
	}
	mux := http.ServeMux{}
	mux.Handle("/", wrapPanic(http.HandlerFunc(panickingHandler)))
	ch := make(chan error)
	go func() {
		ch <- http.Serve(ln, &mux)
	}()

	// Call the server once to force a stack trace to be printed.
	resp, err := http.Get("http://" + ln.Addr().String() + "/")
	if err != nil {
		log.Fatal(err)
	}
	b, err := io.ReadAll(resp.Body)
	if err != nil {
		log.Fatal(err)
	}
	resp.Body.Close()
	if v := string(b); v != "Done" {
		log.Fatal(v)
	}

	// Close the server.
	if err := ln.Close(); err != nil {
		log.Fatal(err)
	}
	<-ch
	// Output:
	// recovered: "It happens"
	// Parsed stack:
	//     stack_test example_test.go:239 recoverPanic(<args>)
	//     stack_test example_test.go:233 panickingHandler(<args>)
	//     stack_test example_test.go:295 Example_httpHandlerMiddleware.wrapPanic.func2(<args>)
}

// panickingHandler is an http.HandlerFunc that panics.
func panickingHandler(w http.ResponseWriter, r *http.Request) {