Merge branch 'fix-dead-help-link' into 'master'

Fix a broken link and avoid potential creation of future broken links on the help page.

See merge request !7582

app/controllers/help_controller.rb

@@ -6,9 +6,9 @@ class HelpController < ApplicationController
   def index
     @help_index = File.read(Rails.root.join('doc', 'README.md'))
 
-    # Prefix Markdown links with `help/` unless they already have been
-    # See http://rubular.com/r/ie2MlpdUMq
-    @help_index.gsub!(/(\]\()(\/?help\/)?([^\)\(]+\))/, '\1/help/\3')
+    # Prefix Markdown links with `help/` unless they are external links
+    # See http://rubular.com/r/MioSrVLK3S
+    @help_index.gsub!(%r{(\]\()(?!.+://)([^\)\(]+\))}, '\1/help/\2')
   end
 
   def show

spec/controllers/help_controller_spec.rb

@@ -16,14 +16,6 @@ describe HelpController do
       end
     end
 
-    context 'when url prefixed with help/' do
-      it 'will be an absolute path' do
-        stub_readme("[API](help/api/README.md)")
-        get :index
-        expect(assigns[:help_index]).to eq '[API](/help/api/README.md)'
-      end
-    end
-
     context 'when url prefixed with help' do
       it 'will be an absolute path' do
         stub_readme("[API](helpful_hints/README.md)")
@@ -32,11 +24,11 @@ describe HelpController do
       end
     end
 
-    context 'when url prefixed with /help/' do
+    context 'when url is an external link' do
       it 'will not be changed' do
-        stub_readme("[API](/help/api/README.md)")
+        stub_readme("[external](https://some.external.link)")
         get :index
-        expect(assigns[:help_index]).to eq '[API](/help/api/README.md)'
+        expect(assigns[:help_index]).to eq '[external](https://some.external.link)'
       end
     end
   end

spec/features/help_pages_spec.rb

@@ -10,4 +10,28 @@ describe 'Help Pages', feature: true do
       expect(page).to have_content("ssh-keygen -t rsa -C \"#{@user.email}\"")
     end
   end
+
+  describe 'Get the main help page' do
+    shared_examples_for 'help page' do
+      it 'prefixes links correctly' do
+        expect(page).to have_selector('div.documentation-index > ul a[href="/help/api/README.md"]')
+      end
+    end
+
+    context 'without a trailing slash' do
+      before do
+        visit help_path
+      end
+
+      it_behaves_like 'help page'
+    end
+
+    context 'with a trailing slash' do
+      before do
+        visit help_path + '/'
+      end
+
+      it_behaves_like 'help page'
+    end
+  end
 end