test_ellipsis_forwarding_for_mapply <- function() { mapply_wrapper <- function(FUN, x, ...) mapply(FUN, x, ...) x <- list(a=1:3, 1:2) y <- list(104:105, B=103) target <- mapply(append, x, y) checkIdentical(target, mapply_wrapper(append, x, y)) MoreArgs <- list(after=0) target <- mapply(append, x, y, MoreArgs=MoreArgs) current <- mapply_wrapper(append, x, y, MoreArgs=MoreArgs) checkIdentical(target, current) MoreArgs <- list(after=2) target <- mapply(append, x, y, MoreArgs=MoreArgs, USE.NAMES=FALSE) current <- mapply_wrapper(append, x, y, MoreArgs=MoreArgs, USE.NAMES=FALSE) checkIdentical(target, current) }