Prevent rich_text_area from raising when inexistent attribute is passed (#24)

When an inexistent attribute is passed as a parameter to currently
existing Rails' Form Helpers they render an empty tag instead of
raising an exception. This commit confers the same behavior to
`rich_text_area`.

Fixes #19

2 files changed, 22 insertions, 1 deletions

diff --git a/app/helpers/action_text/tag_helper.rb b/app/helpers/action_text/tag_helper.rb
index 103b65eb97..c7ba416880 100644
--- a/app/helpers/action_text/tag_helper.rb
+++ b/app/helpers/action_text/tag_helper.rb
@@ -45,7 +45,7 @@ module ActionView::Helpers
     end
 
     def editable_value
-      value.body.try(:to_trix_html)
+      value&.body.try(:to_trix_html)
     end
   end
 
diff --git a/test/template/form_helper_test.rb b/test/template/form_helper_test.rb
new file mode 100644
index 0000000000..d7bdbad26c
--- /dev/null
+++ b/test/template/form_helper_test.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class ActionText::FormHelperTest < ActionView::TestCase
+  tests ActionText::TagHelper
+
+  def form_with(*)
+    @output_buffer = super
+  end
+
+  test "rich_text_area doesn't raise when attributes don't exist in the model" do
+    assert_nothing_raised do
+      form_with(model: Message.new, scope: :message, id: "create-message") do |form|
+        form.rich_text_area(:not_an_attribute)
+      end
+    end
+
+    assert_match "message[not_an_attribute]", output_buffer
+  end
+end