Check if columns are renamed when unnesting

Question

Is there a way to know if a table was renamed in the process of unnesting? I want to know if there is something where I can intercept any messages that come through with New names: and give more context about solutions

# min reprex
library(tidyverse)

f <- function() { 
  tibble(
    x = 1:2, 
    y = 2:1, 
    z = tibble(x = 1)
  ) |> 
    unnest_wider(z, names_repair = "unique")
}

f()

New names:
• `x` -> `x...1`
• `x` -> `x...3`

 x...1     y x...3
 ----- ----- -----
     1     2     1
     2     1     1

---

More context:

• The message stems from

  vctrs::vec_as_names(c("x", "x"), repair = "universal")
  

• I see information about withCallingHandlers() but not sure if that is the right route. I thought there was a way for errors/messages to have classes that you can intercept but I can't remember what I read.

• Something in testthat::expect_message() may help. I thought there would be a has_message() function out there.

• There is a lot of tidy evaluation and comparing names before and after might be tricky. I could look for the names with the regex "\\.+\\d+$" but not sure that is robust enough since data could have fields with that syntax already.

Answer 1

Taking inspiration from hadley's answer, on the question that @ritchie-sacramento linked, you should check out the evaluate package.

> eval_res <- evaluate::evaluate("f()")
> eval_res[[2]]$message
[1] "New names:\n* x -> x...1\n* x -> x...3\n"

This will require more testing to see what happens to the data structure when there are errors, warnings, or even multiple messages. But this seems like the right track.