Ensure slice_*() family throw the right error when namespace prefix…

…ed (#6955)

* Turn the expression into a string label early

* NEWS bullet

NEWS.md

@@ -1,5 +1,8 @@
 # dplyr (development version)
 
+* `slice_*()` now throw the correct error if you forget to name `n` while also
+  prefixing the call with `dplyr::` (#6946).
+
 * `join_by()` now allows its helper functions to be namespaced with `dplyr::`,
   like `join_by(dplyr::between(x, lower, upper))` (#6838).
 

R/slice.R

@@ -464,6 +464,7 @@ check_slice_unnamed_n_prop <- function(..., n, prop, error_call = caller_env())
 
   if (length(dots) == 1L && names2(dots)[[1L]] == "") {
     slice_call <- frame_call(frame = error_call)[[1]]
+    slice_call <- as_label(slice_call)
     bullets <- c(
       "`n` must be explicitly named.",
       i = glue("Did you mean `{slice_call}(n = {as_label(dots[[1]])})`?")

tests/testthat/_snaps/slice.md

@@ -228,6 +228,39 @@
       ! `n` must be explicitly named.
       i Did you mean `slice_sample(n = 5)`?
 
+---
+
+    Code
+      dplyr::slice_head(df, 5)
+    Condition
+      Error in `dplyr::slice_head()`:
+      ! `n` must be explicitly named.
+      i Did you mean `dplyr::slice_head(n = 5)`?
+    Code
+      dplyr::slice_tail(df, 5)
+    Condition
+      Error in `dplyr::slice_tail()`:
+      ! `n` must be explicitly named.
+      i Did you mean `dplyr::slice_tail(n = 5)`?
+    Code
+      dplyr::slice_min(df, x, 5)
+    Condition
+      Error in `dplyr::slice_min()`:
+      ! `n` must be explicitly named.
+      i Did you mean `dplyr::slice_min(n = 5)`?
+    Code
+      dplyr::slice_max(df, x, 5)
+    Condition
+      Error in `dplyr::slice_max()`:
+      ! `n` must be explicitly named.
+      i Did you mean `dplyr::slice_max(n = 5)`?
+    Code
+      dplyr::slice_sample(df, 5)
+    Condition
+      Error in `dplyr::slice_sample()`:
+      ! `n` must be explicitly named.
+      i Did you mean `dplyr::slice_sample(n = 5)`?
+
 ---
 
     Code

tests/testthat/test-slice.R

@@ -320,8 +320,8 @@ test_that("slice_*() doesn't look for `n` in data (#6089)", {
 
 test_that("slice_*() checks that `n=` is explicitly named and ... is empty", {
   # i.e. that every function calls check_slice_dots()
-
   df <- data.frame(x = 1:10)
+
   expect_snapshot(error = TRUE, {
     slice_head(df, 5)
     slice_tail(df, 5)
@@ -330,6 +330,15 @@ test_that("slice_*() checks that `n=` is explicitly named and ... is empty", {
     slice_sample(df, 5)
   })
 
+  # And works with namespace prefix (#6946)
+  expect_snapshot(error = TRUE, {
+    dplyr::slice_head(df, 5)
+    dplyr::slice_tail(df, 5)
+    dplyr::slice_min(df, x, 5)
+    dplyr::slice_max(df, x, 5)
+    dplyr::slice_sample(df, 5)
+  })
+
   expect_snapshot(error = TRUE, {
     slice_head(df, 5, 2)
     slice_tail(df, 5, 2)