Added curso test

pkg/mongo/cursor_test.go

@@ -0,0 +1,55 @@
+package mongo
+
+import (
+	"strings"
+	"testing"
+
+	"go.mongodb.org/mongo-driver/v2/bson"
+)
+
+func TestEncodeDecodePageCursor(t *testing.T) {
+	encoded, err := encodePageCursor("created_at", -1, int64(1700000000), "507f1f77bcf86cd799439011", "abc123", 10)
+	if err != nil {
+		t.Fatalf("encode: %v", err)
+	}
+	if strings.Contains(encoded, "+") || strings.Contains(encoded, "/") {
+		t.Fatalf("expected URL-safe cursor, got %q", encoded)
+	}
+
+	decoded, err := decodePageCursor(encoded)
+	if err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+
+	if decoded.SortField != "created_at" || decoded.SortOrder != -1 {
+		t.Fatalf("unexpected sort: %+v", decoded)
+	}
+	if decoded.FiltersHash != "abc123" || decoded.PageOffset != 10 {
+		t.Fatalf("unexpected metadata: %+v", decoded)
+	}
+}
+
+func TestBuildListPaginationCursorAndOffsetConflict(t *testing.T) {
+	_, err := BuildListPagination(10, 5, "cursor-token", "created_at", "desc", bson.M{}, ListPaginationOptions{})
+	if err == nil {
+		t.Fatal("expected error when cursor and offset are both set")
+	}
+}
+
+func TestBuildListPaginationOffsetMode(t *testing.T) {
+	p, err := BuildListPagination(10, 20, "", "created_at", "desc", bson.M{"status": "active"}, ListPaginationOptions{})
+	if err != nil {
+		t.Fatalf("build: %v", err)
+	}
+	if p.Skip != 20 || p.Limit != 10 || p.Cursor != "" {
+		t.Fatalf("unexpected pagination: %+v", p)
+	}
+}
+
+func TestHashFilterStable(t *testing.T) {
+	a := HashFilter(bson.M{"status": "active"})
+	b := HashFilter(bson.M{"status": "active"})
+	if a == "" || a != b {
+		t.Fatalf("expected stable non-empty hash, got %q and %q", a, b)
+	}
+}