Same problem here. When I use the "testthat" library on my machine and run the exact same testing code it works fine. It throws the same error as you posted when I run it on Codewars.

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My Code worke fine in RStudio. On Codewars, i get an error message:

Test Failed
object 'i' not found
1: expect_equal(f(5), 3) at tests.R:3
2: quasi_label(enquo(object), label)
3: eval_bare(get_expr(quo), get_env(quo))
4: f(5)

In R it works fine. But Codewars sends me:

Test Failed
actual not equal to expected.
'current' is not a factor

Why a factor? It has to be a character. as.factor not work...