fix: keep failed login authentication unchanged

memory_auth_test.go

@@ -8,6 +8,7 @@ import (
 	"net/http/httptest"
 	"os"
 	"path/filepath"
+	"reflect"
 	"strings"
 	"testing"
 )
@@ -115,6 +116,12 @@ func TestFreshMemoryClientQRLoginPersistsThroughCallback(t *testing.T) {
 	server = httptest.NewServer(http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
 		switch request.URL.Path {
 		case "/serviceLogin":
+			deviceID, deviceErr := request.Cookie("deviceId")
+			passO, passOErr := request.Cookie("pass_o")
+			if request.UserAgent() == "" || deviceErr != nil || deviceID.Value == "" || passOErr != nil || passO.Value == "" {
+				http.Error(writer, "missing generated login identity", http.StatusBadRequest)
+				return
+			}
 			_, _ = io.WriteString(writer, `&&&START&&&{"code":70016,"location":"`+server.URL+`/prepare"}`)
 		case "/loginUrl":
 			_, _ = io.WriteString(writer, `&&&START&&&{"code":0,"loginUrl":"https://qr.example/login","lp":"`+server.URL+`/lp"}`)
@@ -148,6 +155,53 @@ func TestFreshMemoryClientQRLoginPersistsThroughCallback(t *testing.T) {
 	}
 }
 
+func TestFreshMemoryClientQRLoginCallbackFailureKeepsZeroAuthData(t *testing.T) {
+	var client *Client
+	var callbackCalls int
+	var server *httptest.Server
+	server = httptest.NewServer(http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
+		switch request.URL.Path {
+		case "/serviceLogin":
+			_, _ = io.WriteString(writer, `&&&START&&&{"code":70016,"location":"`+server.URL+`/prepare"}`)
+		case "/loginUrl":
+			_, _ = io.WriteString(writer, `&&&START&&&{"code":0,"loginUrl":"https://qr.example/login","lp":"`+server.URL+`/lp"}`)
+		case "/lp":
+			_, _ = io.WriteString(writer, `&&&START&&&{"code":0,"ssecurity":"`+testSsecurity+`","passToken":"pass","userId":"user","cUserId":"c-user","location":"`+server.URL+`/callback"}`)
+		case "/callback":
+			http.SetCookie(writer, &http.Cookie{Name: "serviceToken", Value: "service", Path: "/"})
+			_, _ = io.WriteString(writer, "ok")
+		default:
+			http.NotFound(writer, request)
+		}
+	}))
+	defer server.Close()
+
+	var err error
+	client, err = NewClientWithAuthData(AuthData{}, WithHTTPClient(server.Client()), WithQRWriter(io.Discard), WithAuthDataChanged(func(AuthData) error {
+		callbackCalls++
+		if current := client.AuthData(); !reflect.DeepEqual(current, AuthData{}) {
+			t.Fatalf("auth data installed before callback completed: %#v", current)
+		}
+		return errAuthDataChanged
+	}))
+	if err != nil {
+		t.Fatal(err)
+	}
+	client.serviceLoginURL = server.URL + "/serviceLogin"
+	client.loginURL = server.URL + "/loginUrl"
+
+	_, err = client.Login(context.Background())
+	if !errors.Is(err, errAuthDataChanged) {
+		t.Fatalf("Login() error = %v, want %v", err, errAuthDataChanged)
+	}
+	if callbackCalls != 1 {
+		t.Fatalf("auth data changed callback calls = %d, want 1", callbackCalls)
+	}
+	if authData := client.AuthData(); !reflect.DeepEqual(authData, AuthData{}) {
+		t.Fatalf("auth data after callback failure = %#v, want exact zero value", authData)
+	}
+}
+
 func TestFileRefreshPersistenceFailureRollsBack(t *testing.T) {
 	directory := t.TempDir()
 	authPath := filepath.Join(directory, "auth.json")