tabyl() does not call left_join() due to breaking changes in dplyr 0.6.0

NA no longer joined to NA.  Closes #111

R/tabyl.R

@@ -59,7 +59,12 @@ tabyl.default <- function(vec, sort = FALSE, show_na = TRUE, ...) {
     result <- dat %>% dplyr::count(vec, sort = sort)
 
     if(is.factor(vec)){
-      result <- tidyr::complete(result, vec)
+      expanded <- tidyr::expand(result, vec)
+      result <- merge(x = expanded, # can't use dplyr::left_join because as of 0.6.0, NAs don't match, and na_matches argument not present < 0.6.0
+                      y = result,
+                      by = "vec",
+                      all.x = TRUE)
+      result <- dplyr::arrange(result, vec) # restore sorting by factor level
       if(sort){result <- dplyr::arrange(result, dplyr::desc(n))} # undo reorder caused by complete()
     }
 

tests/testthat/test-tabyl.R

@@ -37,7 +37,7 @@ test_that("show_NA = FALSE parameter works", {
                tabyl(test_df_na$grp, show_na = FALSE))
 })
 
-test_that("sorting is preserved for factors", {
+test_that("ordering of result by factor levels is preserved for factors", {
   expect_equal(tabyl(factor(c("x", "y", "z"), levels = c("y", "z", "x")))[[1]], factor(c("y", "z", "x"), levels = c("y", "z", "x")))
 })