Don't warn if fct_other() doesn't replace (#327)

Fixes #265

NEWS.md

@@ -1,5 +1,8 @@
 # forcats (development version)
 
+* `fct_other()` no longer generates a warning if no levels are replaced with
+  other (#265).
+
 # forcats 0.5.2
 
 * New `fct()` which works like `factor()` but errors if values of `x`

R/other.R

@@ -25,6 +25,10 @@ fct_other <- function(f, keep, drop, other_level = "Other") {
     levels[levels %in% drop] <- other_level
   }
 
+  if (!other_level %in% levels) {
+    return(f)
+  }
+
   f <- lvls_revalue(f, levels)
   fct_relevel(f, other_level, after = Inf)
 }

tests/testthat/test-other.R

@@ -13,6 +13,12 @@ test_that("drops levels in drop", {
   expect_equal(levels(x2), c("b", "Other"))
 })
 
+test_that("works without warning if no levels replaced", {
+  x <- factor("a")
+  expect_no_warning(fct_other(x, keep = "a"))
+  expect_no_warning(fct_other(x, drop = "b"))
+})
+
 test_that("must supply exactly one of drop and keep", {
   f <- factor(c("a", "b"))