Add test to make sure form_for is not affected by

form_with_generates_ids

actionview/test/template/form_helper_test.rb

@@ -1560,6 +1560,38 @@ def test_form_for
     assert_dom_equal expected, output_buffer
   end
 
+  def test_form_for_is_not_affected_by_form_with_generates_ids
+    old_value = ActionView::Helpers::FormHelper.form_with_generates_ids
+    ActionView::Helpers::FormHelper.form_with_generates_ids = false
+
+    form_for(@post, html: { id: "create-post" }) do |f|
+      concat f.label(:title) { "The Title" }
+      concat f.text_field(:title)
+      concat f.text_area(:body)
+      concat f.check_box(:secret)
+      concat f.submit("Create post")
+      concat f.button("Create post")
+      concat f.button {
+        concat content_tag(:span, "Create post")
+      }
+    end
+
+    expected = whole_form("/posts/123", "create-post", "edit_post", method: "patch") do
+      "<label for='post_title'>The Title</label>" \
+      "<input name='post[title]' type='text' id='post_title' value='Hello World' />" \
+      "<textarea name='post[body]' id='post_body'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[secret]' type='hidden' value='0' />" \
+      "<input name='post[secret]' checked='checked' type='checkbox' id='post_secret' value='1' />" \
+      "<input name='commit' data-disable-with='Create post' type='submit' value='Create post' />" \
+      "<button name='button' type='submit'>Create post</button>" \
+      "<button name='button' type='submit'><span>Create post</span></button>"
+    end
+
+    assert_dom_equal expected, output_buffer
+  ensure
+    ActionView::Helpers::FormHelper.form_with_generates_ids = old_value
+  end
+
   def test_form_for_with_collection_radio_buttons
     post = Post.new
     def post.active; false; end