Merge pull request #540 from yjunechoe/has_columns-character-bugfix

bugfix `has_columns()` passing character vector of non-existing columns

R/has_columns.R

@@ -206,20 +206,23 @@ has_columns <- function(
                              allow_empty = FALSE, call = .call),
       error = function(cnd) cnd
     )
-    ## Check for error from {tidyselect}
+    ## If error from {tidyselect}, counts as no selection
     if (rlang::is_error(columns)) {
       cnd <- columns
       # Rethrow error if genuine evaluation error
       if (inherits(cnd, "resolve_eval_err")) {
         rlang::cnd_signal(cnd)
       } 
-      # 0-vector if "column not found" or "0 columns" error
+      # Return length-0 vector if "column not found" or "0 columns" error
       return(character(0L))
+    } else {
+    ## If columns succesfully resolved to character, return only existing ones
+      return(intersect(columns, colnames(x)))
     }
-    # vector of selections if successful
-    return(columns)
   }
 
+  # A list of columns (character vector) selected by elements of `columns`
+  # - Ex: `c(a, b:c)` becomes `list("a", c("b", "c"))` if data has those columns
   columns_list <- lapply(column_quos, has_column)
   all(lengths(columns_list) > 0L)
 

tests/testthat/test-has_columns.R

@@ -9,8 +9,12 @@ test_that("the `has_columns()` function works when used directly with data", {
   expect_true(small_table %>% has_columns(c(vars(a, b), vars(c))))
 
   # Expect FALSE when *any* of the given column names is absent 
-  expect_false(small_table %>% has_columns(vars(a, h)))
-  expect_false(small_table %>% has_columns(vars(h, j)))
+  expect_false(small_table %>% has_columns(vars(z)))
+  expect_false(small_table %>% has_columns("z"))
+  expect_false(small_table %>% has_columns(vars(a, z)))
+  expect_false(small_table %>% has_columns(vars(z, zz)))
+  expect_false(small_table %>% has_columns(c("a", "z")))
+  expect_false(small_table %>% has_columns(c("z", "zz")))
 
   # Expect that using inputs that are not tabular result in errors
   expect_error(has_columns(list(a = "2"), "a"))
@@ -34,6 +38,9 @@ test_that("the `has_columns()` function works with tidyselect", {
   expect_false(small_table %>% has_columns(last_col() + 1))
   expect_false(small_table %>% has_columns(matches("z")))
 
+  # Expect FALSE when *any* of the given column names is absent 
+  expect_false(small_table %>% has_columns(c(a, z)))
+
   # Genuine evaluation errors are re-thrown and short-circuits
   expect_error(small_table %>% has_columns(stop("Oh no!")), "Oh no!")
   expect_error(small_table %>% has_columns(c(stop("Oh no!"))), "Oh no!")