deprec-do.md
In dplyr: A Grammar of Data Manipulation

do() gives meaningful error messages

Code
  (expect_error(df %>% do(head, tail)))
Output
  <error/rlang_error>
  Error in `do()`:
  ! Can only supply one unnamed argument, not 2.
Code
  (expect_error(df %>% ungroup() %>% do(1)))
Output
  <error/rlang_error>
  Error in `do()`:
  ! Result must be a data frame, not numeric.
Code
  (expect_error(df %>% do(1)))
Output
  <error/rlang_error>
  Error in `do()`:
  ! Results 1, 2, 3 must be data frames, not numeric.
Code
  (expect_error(df %>% do("a")))
Output
  <error/rlang_error>
  Error in `do()`:
  ! Results 1, 2, 3 must be data frames, not character.
Code
  (expect_error(df %>% do(x = 1, 2)))
Output
  <error/rlang_error>
  Error in `do()`:
  ! Arguments must either be all named or all unnamed.