diff --git a/lib/groonga/query.rb b/lib/groonga/query.rb
new file mode 100644
index 00000000..c4eed767
--- /dev/null
+++ b/lib/groonga/query.rb
@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2019  Horimoto Yasuhiro <horimoto@clear-code.com>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License version 2.1 as published by the Free Software Foundation.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+class Groonga
+  module Query
+    class << self
+      def expand(query, expander, flags)
+        
+      end
+    end
+  end
+end
diff --git a/test/test-query.rb b/test/test-query.rb
new file mode 100644
index 00000000..6e34902b
--- /dev/null
+++ b/test/test-query.rb
@@ -0,0 +1,30 @@
+# Copyright (C) 2019  Horimoto Yasuhiro <horimoto@clear-code.com>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License version 2.1 as published by the Free Software Foundation.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+class QueryTest < Test::Unit::TestCase
+  include GroongaTestUtils
+
+  def setup
+    @query = Groonga::Query.new
+  end
+
+  def test_expand
+    expanded_query = @query.expand(:query => "Groonga",
+                                   :expander => "QueryExpanderTSV",
+                                   :flags => 0)
+    assert_equal("((Groonga) OR (Mroonga) OR (PGroonga) OR (Rroonga))",
+                 expanded_query)
+  end
+end