R how get a date from variable in character

I have data that has dates in a character format, as "JAN2005","FEB2005","MAR2005", such as :

Test <- data.table(c("JAN2005","FEB2005","MAR2005","APR2005"),c(436.6,543.1,417.3,687.4))

Is there a simple way to get the date in an actual date format ?