Add bootstrap_fields_for form helper.

lib/bootstrap_form/action_view_extensions/form_helper.rb

@@ -39,7 +39,7 @@ def bootstrap_form_tag(options={}, &block)
         bootstrap_form_for("", options, &block)
       end
 
-      def bootstrap_fields_for(record_name, record_object = nil, options = {}, &block)
+      def bootstrap_fields_for(record_name, record_object=nil, options={}, &block)
         options[:builder] = BootstrapForm::FormBuilder
         fields_for(record_name, record_object, options, &block)
       end

test/bootstrap_fields_for_test.rb

@@ -0,0 +1,49 @@
+require_relative "test_helper"
+
+class BootstrapFieldsForTest < ActionView::TestCase
+  include BootstrapForm::ActionViewExtensions::FormHelper
+
+  setup :setup_test_fixture
+
+  test "bootstrap_fields_for helper works for associations" do
+    @user.address = Address.new(street: "123 Main Street")
+
+    output = bootstrap_form_for(@user) do |_f|
+      bootstrap_fields_for @user.address do |af|
+        af.text_field(:street)
+      end
+    end
+
+    expected = <<~HTML
+      <form accept-charset="UTF-8" action="/users" class="new_user" id="new_user" method="post">
+        #{'<input name="utf8" type="hidden" value="&#x2713;"/>' unless ::Rails::VERSION::STRING >= '6'}
+        <div class="mb-3">
+          <label class="form-label" for="address_street">Street</label>
+          <input class="form-control" id="address_street" name="address[street]" type="text" value="123 Main Street" />
+        </div>
+      </form>
+    HTML
+    assert_equivalent_html expected, output
+  end
+
+  test "bootstrap_form_for helper works for serialized hash attributes" do
+    @user.preferences = { "favorite_color" => "cerulean" }
+
+    output = bootstrap_form_for(@user) do |_f|
+      bootstrap_fields_for :preferences do |builder|
+        builder.text_field :favorite_color, value: @user.preferences["favorite_color"]
+      end
+    end
+
+    expected = <<~HTML
+      <form accept-charset="UTF-8" action="/users" class="new_user" id="new_user" method="post">
+        #{'<input name="utf8" type="hidden" value="&#x2713;"/>' unless ::Rails::VERSION::STRING >= '6'}
+        <div class="mb-3">
+          <label class="form-label" for="preferences_favorite_color">Favorite color</label>
+          <input class="form-control" id="preferences_favorite_color" name="preferences[favorite_color]" type="text" value="cerulean" />
+        </div>
+      </form>
+    HTML
+    assert_equivalent_html expected, output
+  end
+end