mimeTypeHelper.useFilename = true;
        assertContentType("text/plain", "test/text1.txt", "hoge.txt");
        assertContentType("text/plain", null, "hoge.txt");
        assertContentType("text/html", "html/test1.html", "hoge.html");
        assertContentType("text/html", "html/test1.html", "hoge.htm");
        assertContentType("text/html", "html/test1.shtml", "hoge.shtml");

        assertContentType("application/msword", "test/text1.txt", "hoge.doc");