Ignore missing facet specs (#4383)

Author: yutannihilation

R/facet-.r

@@ -329,8 +329,8 @@ validate_facets <- function(x) {
 # Flatten a list of quosures objects to a quosures object, and compact it
 compact_facets <- function(x) {
   x <- flatten_if(x, is_list)
-  null <- vapply(x, quo_is_null, logical(1))
-  new_quosures(x[!null])
+  null_or_missing <- vapply(x, function(x) quo_is_null(x) || quo_is_missing(x), logical(1))
+  new_quosures(x[!null_or_missing])
 }
 
 # Compatibility with plyr::as.quoted()

tests/testthat/test-facet-.r

@@ -52,13 +52,25 @@ test_that("facets reject aes()", {
 test_that("wrap_as_facets_list() returns a quosures object with compacted", {
   expect_identical(wrap_as_facets_list(vars(foo)), quos(foo = foo))
   expect_identical(wrap_as_facets_list(~foo + bar), quos(foo = foo, bar = bar))
-  expect_identical(wrap_as_facets_list(vars(foo, NULL, bar)), quos(foo = foo, bar = bar))
+
+  f <- function(x) {
+    expect_identical(wrap_as_facets_list(vars(foo, {{ x }}, bar)), quos(foo = foo, bar = bar))
+  }
+
+  f(NULL)
+  f()
 })
 
 test_that("grid_as_facets_list() returns a list of quosures objects with compacted", {
   expect_identical(grid_as_facets_list(vars(foo), NULL), list(rows = quos(foo = foo), cols = quos()))
   expect_identical(grid_as_facets_list(~foo, NULL), list(rows = quos(), cols = quos(foo = foo)))
-  expect_identical(grid_as_facets_list(vars(foo, NULL, bar), NULL), list(rows = quos(foo = foo, bar = bar), cols = quos()))
+
+  f <- function(x) {
+    expect_identical(grid_as_facets_list(vars(foo, {{ x }}, bar), NULL), list(rows = quos(foo = foo, bar = bar), cols = quos()))
+  }
+
+  f(NULL)
+  f()
 })
 
 test_that("wrap_as_facets_list() and grid_as_facets_list() accept empty specs", {