If the focus is in data and analysis I would recommend the exercises in the R for Data Science book from Hadley Wickham (https://r4ds.hadley.nz/). Even if they are simple exercises, they cover a lot.
If the focus is in R programming and package development, then the Advanced R book also by Wickham, https://adv-r.hadley.nz/ has also exercises that come in handy as small tests and also cover all subjects.
If the focus is in data and analysis I would recommend the exercises in the R for Data Science book from Hadley Wickham (https://r4ds.hadley.nz/). Even if they are simple exercises, they cover a lot. If the focus is in R programming and package development, then the Advanced R book also by Wickham, https://adv-r.hadley.nz/ has also exercises that come in handy as small tests and also cover all subjects.