test(agentcompat): harden deterministic fixtures

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

integration/agentcompat/internal/fixture/nat_hold_test.go

@@ -0,0 +1,126 @@
+package fixture
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"io"
+	"net"
+	"net/http"
+	"sync"
+	"testing"
+)
+
+func TestNATHoldBackendObservesBeforeReleaseAndRespondsAfterRelease(t *testing.T) {
+	backend, err := StartNATHoldBackend()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		if err := backend.Close(); err != nil {
+			t.Fatal(err)
+		}
+	}()
+	connection, err := net.Dial("tcp", backend.Address())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer connection.Close()
+	_, err = io.WriteString(connection, "PATCH /hold HTTP/1.1\r\nHost: hold.invalid\r\nX-AgentCompat-Echo: exact\r\nContent-Length: 4\r\n\r\nbody")
+	if err != nil {
+		t.Fatal(err)
+	}
+	record, err := backend.WaitRequest(context.Background())
+	if err != nil || record.Method != "PATCH" || record.Path != "/hold" || record.Host != "hold.invalid" || record.HeaderValue != "exact" || string(record.Body) != "body" {
+		t.Fatalf("record=%+v err=%v", record, err)
+	}
+	select {
+	case <-backend.ResponseReleased():
+		t.Fatal("response released before Release")
+	default:
+	}
+	if err := backend.Release(); err != nil {
+		t.Fatal(err)
+	}
+	response, err := httpReadResponse(connection)
+	if err != nil || response != "method=PATCH\npath=/hold\nhost=hold.invalid\nx-agentcompat-echo=exact\nbody=body\n" {
+		t.Fatalf("response=%q err=%v", response, err)
+	}
+}
+
+func TestNATHoldBackendCloseInterruptsIncompleteRequest(t *testing.T) {
+	backend, err := StartNATHoldBackend()
+	if err != nil {
+		t.Fatal(err)
+	}
+	connection, err := net.Dial("tcp", backend.Address())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := io.WriteString(connection, "GET /incomplete HTTP/1.1\r\nHost: hold.invalid\r\n"); err != nil {
+		t.Fatal(err)
+	}
+	if err := backend.Close(); err != nil {
+		t.Fatal(err)
+	}
+	if err := connection.Close(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestNATHoldBackendCloseIsConcurrentAndRetainsListenerError(t *testing.T) {
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	closeFailure := errors.New("hold listener close failed")
+	backend := newNATHoldBackend(closeErrorListener{Listener: listener, err: closeFailure})
+	connection, err := net.Dial("tcp", backend.Address())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer connection.Close()
+	if _, err := io.WriteString(connection, "GET /hold HTTP/1.1\r\nHost: hold.invalid\r\n"); err != nil {
+		t.Fatal(err)
+	}
+
+	const callers = 8
+	errorsSeen := make(chan error, callers)
+	var group sync.WaitGroup
+	group.Add(callers)
+	for range callers {
+		go func() {
+			defer group.Done()
+			errorsSeen <- backend.Close()
+		}()
+	}
+	group.Wait()
+
+	for range callers {
+		if err := <-errorsSeen; !errors.Is(err, closeFailure) {
+			t.Fatalf("Close error=%v, want %v", err, closeFailure)
+		}
+	}
+	if err := backend.Close(); !errors.Is(err, closeFailure) {
+		t.Fatalf("repeated Close error=%v, want %v", err, closeFailure)
+	}
+}
+
+func newNATHoldBackend(listener net.Listener) *NATHoldBackend {
+	backend := &NATHoldBackend{listener: listener, results: make(chan natHoldResult, 1), done: make(chan struct{}), released: make(chan struct{}), observed: make(chan struct{})}
+	backend.waitGroup.Add(2)
+	go backend.accept()
+	return backend
+}
+
+func httpReadResponse(connection net.Conn) (string, error) {
+	response, err := http.ReadResponse(bufio.NewReader(connection), nil)
+	if err != nil {
+		return "", err
+	}
+	body, err := io.ReadAll(response.Body)
+	if closeErr := response.Body.Close(); err == nil {
+		err = closeErr
+	}
+	return string(body), err
+}