improve error message for non data.frame inputs

NEWS.md

@@ -1,5 +1,8 @@
 # tidyr (development version)
 
+* `pivot_wider_spec()` now throws a more informative error on non-data frame
+  inputs (@catalamarti, #1510).
+
 * tidyr now requires dplyr >=1.1.0 (#1568, @catalamarti).
 
 # tidyr 1.3.1

R/pivot-wide.R

@@ -298,6 +298,7 @@ pivot_wider_spec <- function(data,
                              unused_fn = NULL,
                              error_call = current_env()) {
   check_dots_empty0(...)
+  check_data_frame(data, call = error_call)
 
   spec <- check_pivot_spec(spec, call = error_call)
   check_bool(id_expand, call = error_call)

tests/testthat/_snaps/pivot-wide.md

@@ -1,3 +1,11 @@
+# error if input is not a data.frame
+
+    Code
+      pivot_wider_spec(list(), spec)
+    Condition
+      Error in `pivot_wider_spec()`:
+      ! `data` must be a data frame, not an empty list.
+
 # error when overwriting existing column
 
     Code

tests/testthat/test-pivot-wide.R

@@ -23,6 +23,14 @@ test_that("implicit missings turn into explicit missings", {
   expect_equal(pv$y, c(NA, 2))
 })
 
+test_that("error if input is not a data.frame", {
+  spec <- tibble(.name = "x", .value = "val", )
+  expect_snapshot(
+    pivot_wider_spec(list(), spec),
+    error = TRUE
+  )
+})
+
 test_that("error when overwriting existing column", {
   df <- tibble(
     a = c(1, 1),
@@ -811,4 +819,3 @@ test_that("`id_cols` compat behavior doesn't trigger if named `...` are supplied
     pivot_wider(df, ids = id)
   })
 })
-