Add a breadcrumb at projects/wikis/show.html.haml

app/assets/stylesheets/pages/wiki.scss

@@ -17,6 +17,11 @@
   @extend .top-area;
   position: relative;
 
+  .wiki-breadcrumb {
+    border-bottom: 1px solid $white-normal;
+    padding: 11px 0;
+  }
+
   .wiki-page-title {
     margin: 0;
     font-size: 22px;

app/helpers/wiki_helper.rb

+module WikiHelper
+  # Produces a pure text breadcrumb for a given page.
+  #
+  # page_slug - The slug of a WikiPage object.
+  #
+  # Returns a String composed of the capitalized name of each directory and the
+  # capitalized name of the page itself.
+  def breadcrumb(page_slug)
+    page_slug.split('/').
+      map { |dir_or_page| dir_or_page.gsub(/-+/, ' ').capitalize }.
+      join(' / ')
+  end
+end

app/views/projects/wikis/show.html.haml

@@ -6,6 +6,9 @@
     %button.btn.btn-default.sidebar-toggle.js-sidebar-wiki-toggle{ role: "button", type: "button" }
       = icon('angle-double-left')
 
+    .wiki-breadcrumb
+      %span= breadcrumb(@page.slug)
+
     .nav-text
       %h2.wiki-page-title= @page.title.capitalize
       %span.wiki-last-edit-by

spec/helpers/wiki_helper_spec.rb

+require 'spec_helper'
+
+describe WikiHelper do
+  describe '#breadcrumb' do
+    context 'when the page is at the root level' do
+      it 'returns the capitalized page name' do
+        slug = 'page-name'
+
+        expect(helper.breadcrumb(slug)).to eq('Page name')
+      end
+    end
+
+    context 'when the page is inside a directory' do
+      it 'returns the capitalized name of each directory and of the page itself' do
+        slug = 'dir_1/page-name'
+
+        expect(helper.breadcrumb(slug)).to eq('Dir_1 / Page name')
+      end
+    end
+  end
+end