function run_test() { var zReader = Cc["@mozilla.org/libjar/zip-reader;1"].createInstance( Ci.nsIZipReader ); try { zReader.open(null); do_throw("Shouldn't get here!"); } catch (e) { if ( !(e instanceof Ci.nsIException && e.result == Cr.NS_ERROR_NULL_POINTER) ) { throw e; } // do nothing, this test passes } }