Test argument to collapse

Closes #9
tidyverse · Jan 18, 2017 · f907462 · f907462
1 parent f17ffc4
commit f907462
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Showing 2 changed files with 17 additions and 1 deletion.
diff --git a/R/fstrings.R b/R/fstrings.R
@@ -87,7 +87,11 @@ f <- fstring
 #' # Wide values can be truncated
 #' collapse(f("{1:10}"), width = 5)
 #' @export
-collapse <- function(x, sep = "", width = Inf) {
+collapse <- function(x, sep = "", width = Inf, last = "") {
+  if (nzchar(last) && length(x) > 1) {
+    res <- collapse(x[seq(1, length(x) - 1)], sep = sep, width = Inf)
+    return(collapse(f(res, last, x[length(x)]), width = width))
+  }
   x <- paste0(x, collapse = sep)
   if (width < Inf) {
     x_width <- nchar(x, "width")

diff --git a/tests/testthat/test-collapse.R b/tests/testthat/test-collapse.R
@@ -17,3 +17,15 @@ test_that("collapse truncates", {
   expect_identical("1...", collapse(1:10, width = 4))
   expect_identical("...", collapse(1:10, width = 0))
 })
+
+test_that("last argument to collapse", {
+  expect_equal(collapse(character(), last = " and "), "")
+  expect_equal(collapse("", last = " and "), "")
+  expect_equal(collapse(1, last = " and "), "1")
+  expect_equal(collapse(1:2, last = " and "), "1 and 2")
+  expect_equal(collapse(1:4, ", ", last = " and "), "1, 2, 3 and 4")
+
+  expect_equal(collapse(1:4, ", ", last = " and ", width = 5), "1,...")
+
+  expect_equal(collapse(1:4, ", ", last = " and ", width = 10), "1, 2, 3...")
+})