1 files changed, 93 insertions, 0 deletions
diff --git a/actionview/test/activerecord/form_helper_activerecord_test.rb b/actionview/test/activerecord/form_helper_activerecord_test.rb
new file mode 100644
index 0000000000..34655bfe23
--- /dev/null
+++ b/actionview/test/activerecord/form_helper_activerecord_test.rb
@@ -0,0 +1,93 @@
+# frozen_string_literal: true
+
+require "active_record_unit"
+require "fixtures/project"
+require "fixtures/developer"
+
+class FormHelperActiveRecordTest < ActionView::TestCase
+  tests ActionView::Helpers::FormHelper
+
+  def form_for(*)
+    @output_buffer = super
+  end
+
+  def setup
+    @developer = Developer.new
+    @developer.id   = 123
+    @developer.name = "developer #123"
+
+    @project = Project.new
+    @project.id   = 321
+    @project.name = "project #321"
+    @project.save
+
+    @developer.projects << @project
+    @developer.save
+    super
+    @controller.singleton_class.include Routes.url_helpers
+  end
+
+  def teardown
+    super
+    Project.delete(321)
+    Developer.delete(123)
+  end
+
+  Routes = ActionDispatch::Routing::RouteSet.new
+  Routes.draw do
+    resources :developers do
+      resources :projects
+    end
+  end
+
+  include Routes.url_helpers
+
+  def test_nested_fields_for_with_child_index_option_override_on_a_nested_attributes_collection_association
+    form_for(@developer) do |f|
+      concat f.fields_for(:projects, @developer.projects.first, child_index: "abc") { |cf|
+        concat cf.text_field(:name)
+      }
+    end
+
+    expected = whole_form("/developers/123", "edit_developer_123", "edit_developer", method: "patch") do
+      '<input id="developer_projects_attributes_abc_name" name="developer[projects_attributes][abc][name]" type="text" value="project #321" />' \
+          '<input id="developer_projects_attributes_abc_id" name="developer[projects_attributes][abc][id]" type="hidden" value="321" />'
+    end
+
+    assert_dom_equal expected, output_buffer
+  end
+
+  private
+
+    def hidden_fields(method = nil)
+      txt = +%{<input name="utf8" type="hidden" value="&#x2713;" />}
+
+      if method && !%w(get post).include?(method.to_s)
+        txt << %{<input name="_method" type="hidden" value="#{method}" />}
+      end
+
+      txt
+    end
+
+    def form_text(action = "/", id = nil, html_class = nil, remote = nil, multipart = nil, method = nil)
+      txt =  +%{<form accept-charset="UTF-8" action="#{action}"}
+      txt << %{ enctype="multipart/form-data"} if multipart
+      txt << %{ data-remote="true"} if remote
+      txt << %{ class="#{html_class}"} if html_class
+      txt << %{ id="#{id}"} if id
+      method = method.to_s == "get" ? "get" : "post"
+      txt << %{ method="#{method}">}
+    end
+
+    def whole_form(action = "/", id = nil, html_class = nil, options = nil)
+      contents = block_given? ? yield : ""
+
+      if options.is_a?(Hash)
+        method, remote, multipart = options.values_at(:method, :remote, :multipart)
+      else
+        method = options
+      end
+
+      form_text(action, id, html_class, remote, multipart, method) + hidden_fields(method) + contents + "</form>"
+    end
+end