Raise errors when setting HTML for text content

This adds in a check when specifying HTML in a smart answer (via
govspeak_for or html_for) that it is not for a field that is text only.
This is put in to address a concern that it could be rather easy for
someone to specify `govspeak_for(:title) { "my govspeak" }` and this
produce an unexpected output that no-one notices.

As part of this I removed the govspeak option in DEFAULT_FORMATS as I
didn't think it affected the outcome of any method calls.

Author: kevindew

lib/smart_answer/erb_renderer/format_capture_helper.rb

@@ -2,10 +2,14 @@ module SmartAnswer
   module ErbRenderer::FormatCaptureHelper
     class InvalidFormatType < RuntimeError; end
 
-    DEFAULT_FORMATS = {
-      govspeak: [/^body$/, /^post_body$/, /^next_steps$/],
-      text: [/^title$/, /^meta_description$/, /^hint$/, /^label$/, /^suffix_label$/, /^error_*./],
-    }.freeze
+    TEXT_CONTENT = [
+      :title,
+      :meta_description,
+      :hint,
+      :label,
+      :suffix_label,
+      /^error_/,
+    ].freeze
 
     def render_content_for(name, options = {}, &block)
       format = options.fetch(:format, default_format(name))
@@ -30,10 +34,14 @@ def text_for(name, &block)
     end
 
     def govspeak_for(name, &block)
+      raise ArgumentError, text_only_error_message(name) if text_only?(name)
+
       content_for(name, render_govspeak(capture_content(&block)))
     end
 
     def html_for(name, &block)
+      raise ArgumentError, text_only_error_message(name) if text_only?(name)
+
       content_for(name, capture_content(&block).html_safe)
     end
 
@@ -46,11 +54,17 @@ def capture_content(&block)
     end
 
     def default_format(name)
-      DEFAULT_FORMATS.each do |format, patterns|
-        return format if patterns.any? { |pattern| pattern.match?(name) }
+      text_only?(name) ? :text : :govspeak
+    end
+
+    def text_only?(name)
+      TEXT_CONTENT.any? do |item|
+        item.is_a?(Regexp) ? name.match?(item) : name == item
       end
+    end
 
-      :govspeak
+    def text_only_error_message(name)
+      "#{name} can only be used to display text. Please use #text_for"
     end
 
     def render_govspeak(content)

test/unit/format_capture_helper_test.rb

@@ -67,6 +67,14 @@ def render(component, &block)
         @test_obj.govspeak_for(:name) { "  content" }
         assert_match @test_obj.content_for(:name), "<govspeak><p>content</p>\n</govspeak>"
       end
+
+      should "raise an error when rendering a text only field" do
+        error = assert_raises ArgumentError do
+          @test_obj.govspeak_for(:title) { "Text" }
+        end
+        assert_match "title can only be used to display text. Please use #text_for",
+                     error.message
+      end
     end
 
     context "#html_for" do
@@ -79,6 +87,14 @@ def render(component, &block)
         @test_obj.html_for(:name) { "<p>content</p>" }
         assert @test_obj.content_for(:name).html_safe?
       end
+
+      should "raise an error when rendering a text only field" do
+        error = assert_raises ArgumentError do
+          @test_obj.html_for(:title) { "Text" }
+        end
+        assert_match "title can only be used to display text. Please use #text_for",
+                     error.message
+      end
     end
 
     context "#render_content_for" do