1 files changed, 115 insertions, 0 deletions
diff --git a/hotline/server_test.go b/hotline/server_test.go
index b3f4dce..a6c5e19 100644
--- a/hotline/server_test.go
+++ b/hotline/server_test.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"log/slog"
+	"net"
 	"os"
 	"strings"
 	"testing"
@@ -14,6 +15,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
 	"golang.org/x/text/encoding"
 	"golang.org/x/text/encoding/charmap"
 )
@@ -921,3 +923,116 @@ func TestSendBanMessage(t *testing.T) {
 	assert.Greater(t, buf.Len(), 0)
 	assert.Contains(t, buf.String(), "You are banned")
 }
+
+// findFreePortPair returns a port p where both p and p+1 are free to listen on, as required by
+// ListenAndServe for the Hotline and file transfer listeners.
+func findFreePortPair(t *testing.T) int {
+	t.Helper()
+
+	for range 10 {
+		ln, err := net.Listen("tcp", "127.0.0.1:0")
+		require.NoError(t, err)
+		port := ln.Addr().(*net.TCPAddr).Port
+		_ = ln.Close()
+
+		ln2, err := net.Listen("tcp", fmt.Sprintf("127.0.0.1:%d", port+1))
+		if err != nil {
+			continue
+		}
+		_ = ln2.Close()
+
+		return port
+	}
+
+	t.Fatal("could not find a free port pair")
+	return 0
+}
+
+func TestServer_Serve_returnsOnContextCancel(t *testing.T) {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+
+	srv := &Server{Logger: NewTestLogger()}
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	errCh := make(chan error, 1)
+	go func() { errCh <- srv.Serve(ctx, ln) }()
+
+	// Cancel the context and close the listener, as ListenAndServe's watcher goroutine does.
+	cancel()
+	_ = ln.Close()
+
+	select {
+	case err := <-errCh:
+		assert.ErrorIs(t, err, context.Canceled)
+	case <-time.After(2 * time.Second):
+		t.Fatal("Serve did not return after context cancellation")
+	}
+}
+
+func TestServer_ListenAndServe_returnsOnContextCancel(t *testing.T) {
+	srv, err := NewServer(
+		WithLogger(NewTestLogger()),
+		WithInterface("127.0.0.1"),
+		WithPort(findFreePortPair(t)),
+	)
+	require.NoError(t, err)
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	errCh := make(chan error, 1)
+	go func() { errCh <- srv.ListenAndServe(ctx) }()
+
+	// Give the listeners a moment to start before canceling.
+	time.Sleep(100 * time.Millisecond)
+	cancel()
+
+	select {
+	case err := <-errCh:
+		assert.ErrorIs(t, err, context.Canceled)
+	case <-time.After(2 * time.Second):
+		t.Fatal("ListenAndServe did not return after context cancellation")
+	}
+}
+
+func TestServer_ListenAndServe_returnsErrorWhenPortUnavailable(t *testing.T) {
+	// Occupy a port so ListenAndServe fails to bind to it.
+	blocker, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	defer func() { _ = blocker.Close() }()
+
+	srv, err := NewServer(
+		WithLogger(NewTestLogger()),
+		WithInterface("127.0.0.1"),
+		WithPort(blocker.Addr().(*net.TCPAddr).Port),
+	)
+	require.NoError(t, err)
+
+	err = srv.ListenAndServe(context.Background())
+	assert.Error(t, err)
+	assert.NotErrorIs(t, err, context.Canceled)
+}
+
+func TestServer_Shutdown_stopsListenAndServe(t *testing.T) {
+	srv, err := NewServer(
+		WithLogger(NewTestLogger()),
+		WithInterface("127.0.0.1"),
+		WithPort(findFreePortPair(t)),
+	)
+	require.NoError(t, err)
+
+	errCh := make(chan error, 1)
+	go func() { errCh <- srv.ListenAndServe(context.Background()) }()
+
+	// Give the listeners a moment to start before requesting shutdown.
+	time.Sleep(100 * time.Millisecond)
+	go srv.Shutdown([]byte("goodbye"))
+
+	select {
+	case err := <-errCh:
+		assert.ErrorIs(t, err, context.Canceled)
+	case <-time.After(5 * time.Second): // Shutdown sleeps 3 seconds to flush client queues
+		t.Fatal("ListenAndServe did not return after Shutdown")
+	}
+}