Add specs covering localisation via procs

The :value_method, :text_method and :hint_method params passed to radio
collections and the :hint_method params passed to checkbox collections
now accept procs which can be used to customise the value retrieved from
the item.

This could be used for simple transformations like upcasing the text or
more-complex operations like localising the value, as per the provided
specs

Refs #68

spec/govuk_design_system_formbuilder/builder/check_boxes/collection_spec.rb

@@ -121,6 +121,12 @@
           end
         end
       end
+
+      it_behaves_like 'a field that allows the hint to be localised via a proc' do
+        let(:attribute) { :favourite_colour }
+        let(:i18n_proc) { ->(item) { I18n.t("colours.#{item.name.downcase}") } }
+        let(:args) { [method, attribute, colours, :id, :name].push(i18n_proc) }
+      end
     end
   end
 end

spec/govuk_design_system_formbuilder/builder/radios/collection_spec.rb

@@ -87,6 +87,11 @@
         end
       end
 
+      it_behaves_like 'a field that allows the label to be localised via a proc' do
+        let(:i18n_proc) { ->(item) { I18n.t("colours.#{item.name.downcase}") } }
+        let(:args) { [method, attribute, colours, :id, i18n_proc] }
+      end
+
       context 'radio button hints' do
         let(:colours_with_descriptions) { colours.select { |c| c.description.present? } }
         let(:colours_without_descriptions) { colours.reject { |c| c.description.present? } }
@@ -117,6 +122,11 @@
         specify 'all labels should be bold when hints are enabled' do
           expect(subject).to have_tag('label', with: { class: 'govuk-label--s' }, count: colours.size)
         end
+
+        it_behaves_like 'a field that allows the hint to be localised via a proc' do
+          let(:i18n_proc) { ->(item) { I18n.t("colours.#{item.name.downcase}") } }
+          let(:args) { [method, attribute, colours, :id, :name, i18n_proc] }
+        end
       end
 
       context 'layout direction' do

spec/spec_helper.rb

@@ -1,6 +1,7 @@
 require 'rspec-html-matchers'
 require 'action_view'
 require 'active_model'
+require 'active_support'
 require 'pry'
 require 'simplecov'
 

spec/support/locales/colours.de.yaml

@@ -0,0 +1,5 @@
+colours:
+  red: Rot
+  green: Grün
+  yellow: Gelb
+  blue: Blau

spec/support/localisation.rb

@@ -1,7 +1,16 @@
-def with_localisations(localisations, locale: :en)
+DEFAULT_LOCALE = :en
+
+def with_localisations(localisations, locale: DEFAULT_LOCALE)
+  unless locale.eql?(DEFAULT_LOCALE)
+    I18n.available_locales = [DEFAULT_LOCALE, locale]
+    I18n.locale = locale
+  end
   I18n.backend.store_translations(locale, localisations[locale])
 
   yield
 ensure
+  I18n.available_locales = DEFAULT_LOCALE
+  I18n.locale = DEFAULT_LOCALE
+
   I18n.reload!
 end

spec/support/shared/shared_localisation_examples.rb

@@ -94,3 +94,49 @@
     end
   end
 end
+
+shared_examples 'a field that allows the label to be localised via a proc' do
+  let(:locale) { :de }
+  let(:localisations) do
+    YAML.load_file('spec/support/locales/colours.de.yaml')
+  end
+
+  context 'localising collection items using procs' do
+    subject { builder.send(*args) }
+
+    specify 'labels should be present and correctly-localised' do
+      with_localisations({ locale => localisations }, locale: locale) do
+        colours.each do |c|
+          expect(subject).to have_tag(
+            'label',
+            text: localisations.dig("colours", c.name.downcase),
+            with: { class: 'govuk-label' }
+          )
+        end
+      end
+    end
+  end
+end
+
+shared_examples 'a field that allows the hint to be localised via a proc' do
+  let(:locale) { :de }
+  let(:localisations) do
+    YAML.load_file('spec/support/locales/colours.de.yaml')
+  end
+
+  context 'localising collection items using procs' do
+    subject { builder.send(*args) }
+
+    specify 'hints should be present and correctly-localised' do
+      with_localisations({ locale => localisations }, locale: locale) do
+        colours.each do |c|
+          expect(subject).to have_tag(
+            'span',
+            text: localisations.dig("colours", c.name.downcase),
+            with: { class: 'govuk-hint' }
+          )
+        end
+      end
+    end
+  end
+end