The error message from expect_setequal seems to mix up expected and actual, as illustrated by this example:
expect_setequal(character(), c("A", "B", "C"))
Error: character() (actual) and c("A", "B", "C") (expected) don't have the same values.
* Only in actual: "A", "B", "C"
It should read
Only in expected: "A", "B", "C".
I am using {testthat} version 3.2.1.1.