Raise an ArgumentError when `include_blank` is false for a required field in

`Tags::Base#select_content_tag`.

Previously, passing a falsey value to `include_blank` would be ignored if the
field was required, and a blank line would still be inserted. The following will
now raise instead of quietly failing:

`select("post", "category", %w(a required field), { include_blank: false }, required: 'required')`

1 files changed, 7 insertions, 0 deletions

diff --git a/actionview/test/template/form_options_helper_test.rb b/actionview/test/template/form_options_helper_test.rb
index d25fa3706f..d7daba8bf3 100644
--- a/actionview/test/template/form_options_helper_test.rb
+++ b/actionview/test/template/form_options_helper_test.rb
@@ -645,6 +645,13 @@ class FormOptionsHelperTest < ActionView::TestCase
     )
   end
 
+  def test_select_with_include_blank_false_and_required
+    @post = Post.new
+    @post.category = "<mus>"
+    e = assert_raises(ArgumentError) { select("post", "category", %w( abe <mus> hest), { include_blank: false }, required: 'required') }
+    assert_match(/include_blank cannot be false for a required field./, e.message)
+  end
+
   def test_select_with_blank_as_string
     @post = Post.new
     @post.category = "<mus>"