From 2fd908d42d792e2e284e2d2768d2e867a48b508c Mon Sep 17 00:00:00 2001
From: "d.reznichenko" <d.reznichenko@pin-up.tech>
Date: Tue, 3 Dec 2024 17:42:00 +0100
Subject: [PATCH 1/2] added use of errgroup's ctx to handle feiled http server
 startup gracefully

---
 server.go      |  5 +++--
 server_test.go | 39 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/server.go b/server.go
index e99e31a..1dd8a65 100644
--- a/server.go
+++ b/server.go
@@ -84,7 +84,8 @@ func (s *Server) Start(ctx context.Context) error {
 	shutdownCtx, shutdownCancel := context.WithCancel(context.Background())
 	defer shutdownCancel()
 
-	g, _ := errgroup.WithContext(ctx)
+	// creates ctx which will be canceled on first failed goroutine
+	g, ctx := errgroup.WithContext(ctx)
 
 	// Start the server in a new goroutine within the errgroup
 	g.Go(func() error {
@@ -166,7 +167,7 @@ func (s *Server) Close(ctx context.Context) error {
 // signalChan sets up a channel to listen for OS signals for shutdown
 func signalChan() <-chan os.Signal {
 	stop := make(chan os.Signal, 1)
-	signal.Notify(stop, os.Interrupt, syscall.SIGTERM)
+	signal.Notify(stop, os.Interrupt, syscall.SIGTERM, os.Kill)
 	return stop
 }
 
diff --git a/server_test.go b/server_test.go
index 441eed0..34c528c 100644
--- a/server_test.go
+++ b/server_test.go
@@ -46,7 +46,7 @@ func TestServer(t *testing.T) {
 	cancel()
 
 	// Wait for server to shut down with timeout
-	shutdownTimeout := time.After(5 * time.Second)
+	shutdownTimeout := time.After(time.Second)
 	select {
 	case err := <-serverErr:
 		require.True(t, err == nil || errors.Is(err, context.Canceled),
@@ -59,3 +59,40 @@ func TestServer(t *testing.T) {
 	_, err = http.Get(fmt.Sprintf("http://%s", listenAddr))
 	require.Error(t, err, "Expected error after server shutdown")
 }
+
+func TestErrorServerStart(t *testing.T) {
+	listenAddr := "localhost:9999"
+
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = fmt.Fprintln(w, "Hello, World!")
+	})
+	server, err := httpserver.New(listenAddr, handler)
+	require.NoError(t, err, "Unexpected error creating server")
+
+	// Create a context with cancel for server control
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	// Channel to catch server errors, no need for buffer because we catch error in current test control flow
+	serverErr := make(chan error)
+
+	// Start the server in a goroutine
+	go func() {
+		serverErr <- server.Start(ctx)
+	}()
+	// Start server will wail because of already used port
+	go func() {
+		serverErr <- server.Start(ctx)
+	}()
+
+	select {
+	case err = <-serverErr:
+		require.ErrorIs(t, err, httpserver.ErrServerStart,
+			"Expected ErrServerStart error, got: %v", err)
+	case <-time.After(time.Second):
+		t.Fatal("Server shutdown timed out")
+	}
+	// Verify server is no longer accepting connections
+	_, err = http.Get(fmt.Sprintf("http://%s", listenAddr))
+	require.Error(t, err, "Expected error after server shutdown")
+}

From b946e36cf82f4aa5cbf6d00c0d617b68438789e1 Mon Sep 17 00:00:00 2001
From: "d.reznichenko" <d.reznichenko@pin-up.tech>
Date: Tue, 3 Dec 2024 18:29:31 +0100
Subject: [PATCH 2/2] removed os.Kill signal

---
 server.go      | 2 +-
 server_test.go | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/server.go b/server.go
index 1dd8a65..34b8032 100644
--- a/server.go
+++ b/server.go
@@ -167,7 +167,7 @@ func (s *Server) Close(ctx context.Context) error {
 // signalChan sets up a channel to listen for OS signals for shutdown
 func signalChan() <-chan os.Signal {
 	stop := make(chan os.Signal, 1)
-	signal.Notify(stop, os.Interrupt, syscall.SIGTERM, os.Kill)
+	signal.Notify(stop, os.Interrupt, syscall.SIGTERM)
 	return stop
 }
 
diff --git a/server_test.go b/server_test.go
index 34c528c..11a2432 100644
--- a/server_test.go
+++ b/server_test.go
@@ -16,7 +16,7 @@ func TestServer(t *testing.T) {
 	listenAddr := "localhost:9999"
 
 	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		fmt.Fprintln(w, "Hello, World!")
+		_, _ = fmt.Fprintln(w, "Hello, World!")
 	})
 	server, err := httpserver.New(listenAddr, handler)
 	require.NoError(t, err, "Unexpected error creating server")