minor test update

tests/testthat/test-group-by.r

@@ -214,7 +214,7 @@ test_that("grouped_df requires a list of symbols (#665)", {
 })
 
 test_that("group_by gives meaningful message with unknow column (#716)",{
-  expect_error( group_by(iris, wrong_name_of_variable), "unknown column" )
+  expect_error( group_by(iris, wrong_name_of_variable), "unknown variable to group by" )
 })
 
 test_that("[ on grouped_df preserves grouping if subset includes grouping vars", {
@@ -256,3 +256,15 @@ test_that("ungroup.rowwise_df gives a tbl_df (#936)", {
   res <- tbl_df(mtcars) %>% rowwise %>% ungroup %>% class
   expect_equal( res, c("tbl_df", "data.frame"))
 })
+
+test_that( "group_by supports column (#1012)", {
+  g1 <- mtcars %>% group_by(cyl)
+  g2 <- mtcars %>% group_by(column(~cyl))
+  g3 <- mtcars %>% group_by(column("cyl"))
+  a <- "cyl"
+  g4 <- mtcars %>% group_by(column(a))
+
+  expect_equal( attr(g1, "vars"), attr(g2, "vars"))
+  expect_equal( attr(g1, "vars"), attr(g3, "vars"))
+  expect_equal( attr(g1, "vars"), attr(g4, "vars"))
+})