Give accordion feature parity with nunjucks macros

.rubocop.yml

@@ -21,6 +21,8 @@ Style/TrailingCommaInArguments:
   Enabled: false
 Style/TrailingCommaInHashLiteral:
   Enabled: false
+Style/Lambda:
+  Enabled: false
 Style/StringConcatenation:
   Enabled: false
 Style/TrailingCommaInArrayLiteral:

app/components/govuk_component/accordion_component.html.erb

@@ -1,15 +1,5 @@
 <%= tag.div(id: @id, class: classes, data: { module: 'govuk-accordion' }, **html_attributes) do %>
   <% sections.each do |section| %>
-    <%= tag.div(id: section.id(suffix: 'section'), class: section.classes, **section.html_attributes) do %>
-      <div class="govuk-accordion__section-header">
-        <h2 class="govuk-accordion__section-heading">
-          <%= tag.span(section.title, id: section.id, class: "govuk-accordion__section-button", aria: { expanded: section.expanded?, controls: section.id(suffix: 'content') }) %>
-        </h2>
-        <% if section.summary.present? %>
-          <%= tag.div(section.summary, id: section.id(suffix: 'summary'), class: %w(govuk-accordion__section-summary govuk-body)) %>
-        <% end %>
-      </div>
-      <%= section %>
-    <% end %>
+    <%= section %>
   <% end %>
 <% end %>

app/components/govuk_component/accordion_component.rb

@@ -1,12 +1,23 @@
 class GovukComponent::AccordionComponent < GovukComponent::Base
-  renders_many :sections, "Section"
+  renders_many :sections, ->(heading_text: nil, summary_text: nil, expanded: false, classes: [], html_attributes: {}, &block) do
+    GovukComponent::AccordionComponent::SectionComponent.new(
+      classes: classes,
+      expanded: expanded,
+      heading_level: heading_level,      # set once at parent level, passed to all children
+      html_attributes: html_attributes,
+      summary_text: summary_text,
+      heading_text: heading_text,
+      &block
+    )
+  end
 
-  attr_reader :id
+  attr_reader :id, :heading_level
 
-  def initialize(id: nil, classes: [], html_attributes: {})
+  def initialize(id: nil, heading_level: 2, classes: [], html_attributes: {})
     super(classes: classes, html_attributes: html_attributes)
 
-    @id = id
+    @id            = id
+    @heading_level = heading_tag(heading_level)
   end
 
 private
@@ -15,33 +26,9 @@ def default_classes
     %w(govuk-accordion)
   end
 
-  class Section < GovukComponent::Base
-    attr_reader :title, :summary, :expanded
-
-    alias_method :expanded?, :expanded
-
-    def initialize(title:, summary: nil, expanded: false, classes: [], html_attributes: {})
-      super(classes: classes, html_attributes: html_attributes)
-
-      @title    = title
-      @summary  = summary
-      @expanded = expanded
-    end
-
-    def id(suffix: nil)
-      [title.parameterize, suffix].compact.join('-')
-    end
-
-    def call
-      tag.div(content, id: id(suffix: 'content'), class: %w(govuk-accordion__section-content), aria: { labelledby: id })
-    end
-
-  private
+  def heading_tag(level)
+    fail(ArgumentError, "heading_level must be 1-6") unless level.in?(1..6)
 
-    def default_classes
-      %w(govuk-accordion__section).tap do |classes|
-        classes.append("govuk-accordion__section--expanded") if expanded?
-      end
-    end
+    %(h#{level})
   end
 end

app/components/govuk_component/accordion_component/section_component.html.erb

@@ -0,0 +1,11 @@
+<%= tag.div(id: id(suffix: 'section'), class: classes, **html_attributes) do %>
+  <div class="govuk-accordion__section-header">
+    <%= content_tag(heading_level, class: "govuk-accordion__section-heading") do %>
+      <%= tag.span(heading_content, id: id, class: "govuk-accordion__section-button", aria: { expanded: expanded?, controls: id(suffix: 'content') }) %>
+    <% end %>
+    <% if summary_content.present? %>
+      <%= tag.div(summary_content, id: id(suffix: 'summary'), class: %w(govuk-accordion__section-summary govuk-body)) %>
+    <% end %>
+  </div>
+  <%= tag.div(content, id: id(suffix: 'content'), class: %w(govuk-accordion__section-content), aria: { labelledby: id }) %>
+<% end %>

app/components/govuk_component/accordion_component/section_component.rb

@@ -0,0 +1,41 @@
+class GovukComponent::AccordionComponent::SectionComponent < GovukComponent::Base
+  attr_reader :heading_text, :summary_text, :expanded, :heading_level
+
+  renders_one :heading_html
+  renders_one :summary_html
+
+  alias_method :expanded?, :expanded
+
+  def initialize(heading_text:, summary_text:, expanded:, heading_level:, classes: [], html_attributes: {})
+    super(classes: classes, html_attributes: html_attributes)
+
+    @heading_text  = heading_text
+    @summary_text  = summary_text
+    @expanded      = expanded
+    @heading_level = heading_level
+  end
+
+  def id(suffix: nil)
+    # generate a random number if we don't have heading_text to avoid attempting
+    # to parameterize a potentially-huge chunk of HTML
+    @prefix ||= heading_text&.parameterize || SecureRandom.hex(4)
+
+    [@prefix, suffix].compact.join('-')
+  end
+
+  def heading_content
+    heading_html || heading_text || fail(ArgumentError, "no heading_text or heading_html")
+  end
+
+  def summary_content
+    summary_html || summary_text
+  end
+
+private
+
+  def default_classes
+    %w(govuk-accordion__section).tap do |classes|
+      classes.append("govuk-accordion__section--expanded") if expanded?
+    end
+  end
+end

spec/components/govuk_component/accordion_component_spec.rb

@@ -18,14 +18,16 @@
   let(:kwargs) { { id: id } }
 
   subject! do
-    render_inline(GovukComponent::AccordionComponent.new) do |component|
-      sections.each do |title, content|
-        component.section(title: title) { content }
-      end
+    render_inline(GovukComponent::AccordionComponent.new(**kwargs)) do |component|
+      helper.safe_join(
+        sections.map do |heading_text, content|
+          component.section(heading_text: heading_text) { content }
+        end
+      )
     end
   end
 
-  specify 'renders an container div with the right class' do
+  specify 'renders a container div with the right class' do
     expect(rendered_component).to have_tag('div', with: { class: component_css_class }) do
       with_tag('div', with: { class: 'govuk-accordion__section' })
     end
@@ -42,55 +44,153 @@
   end
 
   describe 'for each section' do
-    specify 'the title and content is present' do
-      sections.each do |title, content|
-        expect(rendered_component).to have_tag('div', with: { class: 'govuk-accordion__section', id: %(#{title.parameterize}-section) }) do
-          with_tag('span', with: { id: title.parameterize, class: 'govuk-accordion__section-button' })
-          with_text(content)
+    specify 'the heading text and content is present' do
+      sections.each do |heading_text, content|
+        expect(rendered_component).to have_tag('div', with: { class: 'govuk-accordion__section', id: %(#{heading_text.parameterize}-section) }) do
+          with_tag('h2', class: 'govuk-accordion__section-heading') do
+            with_tag('span', text: heading_text, with: { id: heading_text.parameterize, class: 'govuk-accordion__section-button' })
+          end
+
+          with_tag('div', with: { id: %(#{heading_text.parameterize}-content), class: 'govuk-accordion__section-content' }, text: content)
         end
       end
     end
 
     specify 'each section ID matches the content aria-labelledby' do
-      sections.each_key do |title|
-        id = title.parameterize
+      sections.each_key do |heading_text|
+        id = heading_text.parameterize
 
         expect(rendered_component).to have_tag('span', with: { id: id, class: 'govuk-accordion__section-button' })
         expect(rendered_component).to have_tag('div', with: { 'aria-labelledby' => id })
       end
     end
 
     specify 'each section ID matches the button aria-controls' do
-      sections.each_key do |title|
-        id = title.parameterize
+      sections.each_key do |heading_text|
+        id = heading_text.parameterize
 
         expect(rendered_component).to have_tag('div', with: { id: %(#{id}-content) })
         expect(rendered_component).to have_tag('span', with: { 'aria-controls' => %(#{id}-content) })
       end
     end
   end
 
+  describe 'overriding the section heading level' do
+    let(:kwargs) { { heading_level: 3 } }
+
+    specify 'has the overriden level' do
+      expect(rendered_component).to have_tag('h3', with: { class: 'govuk-accordion__section-heading' })
+    end
+
+    context 'when the heading level is invalid' do
+      specify 'has the overriden level' do
+        expected_message = "heading_level must be 1-6"
+
+        expect { GovukComponent::AccordionComponent.new(heading_level: 8) }.to raise_error(ArgumentError, expected_message)
+      end
+    end
+  end
+
+  describe 'overriding the section heading with HTML' do
+    let(:custom_tag) { :marquee }
+    let(:custom_text) { "Fanciest accordion heading" }
+    let(:custom_class) { "purple" }
+    let(:custom_content) { "What a nice accordion!" }
+
+    subject! do
+      render_inline(GovukComponent::AccordionComponent.new(**kwargs)) do |component|
+        component.section do |section|
+          section.heading_html do
+            helper.content_tag(custom_tag, custom_text, class: custom_class)
+          end
+
+          custom_content
+        end
+      end
+    end
+
+    specify "renders the custom heading content" do
+      expect(rendered_component).to have_tag("h2", with: { class: "govuk-accordion__section-heading" }) do
+        with_tag(custom_tag, text: custom_text, with: { class: custom_class })
+      end
+    end
+
+    specify "renders the custom content" do
+      expect(rendered_component).to have_tag("div", with: { class: "govuk-accordion__section-content" }, text: custom_content)
+    end
+
+    specify "uses a random string as an identifier to link the heading and content together" do
+      button_identifier = html.at_css('span.govuk-accordion__section-button').attribute('id').value
+      content_identifier = %(#{button_identifier}-content)
+
+      expect(rendered_component).to have_tag('span', with: { id: button_identifier, 'aria-controls' => content_identifier })
+      expect(rendered_component).to have_tag('div', with: { id: content_identifier, 'aria-labelledby' => button_identifier })
+    end
+  end
+
+  describe 'when no heading text or HTML is supplied' do
+    specify "raises an appropriate error" do
+      expect {
+        render_inline(GovukComponent::AccordionComponent.new(**kwargs)) do |component|
+          component.section(summary_text: "A summary")
+        end
+      }.to raise_error(ArgumentError, /no heading_text or heading_html/)
+    end
+  end
+
   describe 'summaries' do
     specify 'no summary by default' do
       expect(rendered_component).not_to have_tag('.govuk-accordion__section-summary')
     end
 
     context 'when a summary text is provided' do
-      let(:title) { 'a thing' }
-      let(:summary_content) { 'some summary content' }
+      let(:heading_text) { 'a thing' }
+      let(:summary_text) { 'some summary content' }
       let(:expected_classes) { %w(govuk-accordion__section-summary govuk-body) }
 
       subject! do
         render_inline(GovukComponent::AccordionComponent.new) do |component|
-          component.section(title: title, summary: summary_content) { 'abc' }
+          component.section(heading_text: heading_text, summary_text: summary_text) { 'abc' }
         end
       end
 
       specify 'the summary is rendered with the right id, class and text' do
         expect(rendered_component).to have_tag('.govuk-accordion__section-header') do
-          with_tag('div', with: { id: %(#{title.parameterize}-summary), class: expected_classes }, text: summary_content)
+          with_tag('div', with: { id: %(#{heading_text.parameterize}-summary), class: expected_classes }, text: summary_text)
+        end
+      end
+    end
+
+    describe 'overriding the section heading with HTML' do
+      let(:custom_tag) { :strong }
+      let(:custom_text) { "This is a summary" }
+      let(:custom_class) { "special" }
+      let(:custom_content) { "What a nice summary!" }
+      let(:heading_text) { "some heading" }
+
+      subject! do
+        render_inline(GovukComponent::AccordionComponent.new(**kwargs)) do |component|
+          component.section(heading_text: heading_text) do |section|
+            section.summary_html do
+              helper.content_tag(custom_tag, custom_text, class: custom_class)
+            end
+
+            custom_content
+          end
         end
       end
+
+      specify "renders the custom summary content" do
+        expect(rendered_component).to have_tag("div", with: { class: "govuk-accordion__section-header" }) do
+          with_tag("div", with: { class: "govuk-accordion__section-summary" }) do
+            with_tag(custom_tag, text: custom_text, with: { class: custom_class })
+          end
+        end
+      end
+
+      specify "renders the custom content" do
+        expect(rendered_component).to have_tag("div", with: { class: "govuk-accordion__section-content" }, text: custom_content)
+      end
     end
   end
 
@@ -100,15 +200,15 @@
   context 'slot arguments' do
     let(:slot) { :section }
     let(:content) { -> { 'some swanky accordion content' } }
-    let(:slot_kwargs) { { title: 'A title', summary: 'A summary' } }
+    let(:slot_kwargs) { { heading_text: 'A heading_text', summary_text: 'A summary' } }
 
     it_behaves_like 'a component with a slot that accepts custom classes'
     it_behaves_like 'a component with a slot that accepts custom html attributes'
 
     specify 'sections have the correct expanded states' do
       render_inline(GovukComponent::AccordionComponent.new) do |component|
-        component.section(expanded: true, title: 'section 1', html_attributes: { id: 'section_1' }) { 'abc' }
-        component.section(title: 'section 2', html_attributes: { id: 'section_2' }) { 'def' }
+        component.section(expanded: true, heading_text: 'section 1', html_attributes: { id: 'section_1' }) { 'abc' }
+        component.section(heading_text: 'section 2', html_attributes: { id: 'section_2' }) { 'def' }
       end
 
       expect(rendered_component).to have_tag('div', with: { id: 'section_1', class: %w(govuk-accordion__section govuk-accordion__section--expanded) })