Fixed another test for Mac

Author: Fifis

tests/testthat/test-step.plugin.R

@@ -4,8 +4,7 @@ test_that("Plug-in step handles inputs well", {
 
 test_that("Plug-in step checks for small truncation errors", {
   expect_equal(step.plugin(sin, pi/3)$exitcode, 0)
-#  expect_equal(step.plugin(sin, pi/4)$exitcode, 1)
-  expect_equal(step.plugin(sin, pi/2)$exitcode, 1)
+  expect_equal(step.plugin(function(x) x, pi/2)$exitcode, 1)
 })
 
 test_that("Plug-in step checks for resprecting the ranges", {