初版功能完成

internal/control/supervisor_test.go

@@ -0,0 +1,79 @@
+package control
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"net/netip"
+	"strconv"
+	"testing"
+	"time"
+)
+
+func TestSupervisorRebindMovesListenerAndPreservesFailedRebind(t *testing.T) {
+	oldAddress := netip.MustParseAddr("127.0.0.1")
+	newAddress := netip.MustParseAddr("127.0.0.2")
+	port := availablePort(t, oldAddress)
+	handler := http.HandlerFunc(func(writer http.ResponseWriter, _ *http.Request) { _, _ = io.WriteString(writer, "ok") })
+	supervisor, err := NewSupervisor(handler, port)
+	if err != nil {
+		t.Fatal(err)
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	if err := supervisor.Start(ctx, oldAddress); err != nil {
+		t.Fatal(err)
+	}
+	defer supervisor.Close()
+	client := &http.Client{Transport: &http.Transport{Proxy: nil}, Timeout: time.Second}
+	assertHTTPBody(t, client, oldAddress, port, "ok")
+
+	occupied, err := net.Listen("tcp4", net.JoinHostPort(newAddress.String(), strconv.Itoa(port)))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := supervisor.Rebind(newAddress); err == nil {
+		occupied.Close()
+		t.Fatal("Rebind succeeded while the target address was occupied")
+	}
+	assertHTTPBody(t, client, oldAddress, port, "ok")
+	if err := occupied.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := supervisor.Rebind(newAddress); err != nil {
+		t.Fatal(err)
+	}
+	assertHTTPBody(t, client, newAddress, port, "ok")
+}
+
+func availablePort(t *testing.T, address netip.Addr) int {
+	t.Helper()
+	listener, err := net.Listen("tcp4", net.JoinHostPort(address.String(), "0"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	port := listener.Addr().(*net.TCPAddr).Port
+	if err := listener.Close(); err != nil {
+		t.Fatal(err)
+	}
+	return port
+}
+
+func assertHTTPBody(t *testing.T, client *http.Client, address netip.Addr, port int, want string) {
+	t.Helper()
+	response, err := client.Get(fmt.Sprintf("http://%s/", net.JoinHostPort(address.String(), strconv.Itoa(port))))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer response.Body.Close()
+	body, err := io.ReadAll(response.Body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(body) != want {
+		t.Fatalf("body=%q, want %q", body, want)
+	}
+}