Show the commit-sha for pre-release versions

The pre-release tags are set at the beginning of a release, so it
would be impossible to figure out which version was running if we're
running nightlies.

In that case it's better to still link to the SHA. These versions
don't get deployed to .com.

app/helpers/version_check_helper.rb

@@ -9,4 +9,17 @@ module VersionCheckHelper
     image_url = VersionCheck.new.url
     image_tag image_url, class: 'js-version-status-badge'
   end
+
+  def link_to_version
+    if Gitlab.pre_release?
+      commit_link = link_to(Gitlab.revision, Gitlab::COM_URL + namespace_project_commits_path('gitlab-org', source_code_project, Gitlab.revision))
+      [Gitlab::VERSION, content_tag(:small, commit_link)].join(' ').html_safe
+    else
+      link_to Gitlab::VERSION, Gitlab::COM_URL + namespace_project_tag_path('gitlab-org', source_code_project, "v#{Gitlab::VERSION}")
+    end
+  end
+
+  def source_code_project
+    'gitlab-ce'
+  end
 end

app/views/help/index.html.haml

@@ -7,7 +7,7 @@
   GitLab
   Community Edition
   - if user_signed_in?
-    %span= link_to Gitlab::VERSION, Gitlab::COM_URL + namespace_project_tag_path('gitlab-org', 'gitlab-ce', "v#{Gitlab::VERSION}")
+    %span= link_to_version
     = version_status_badge
   %hr
 

changelogs/unreleased/bvl-show-pre-release-sha.yml

+---
+title: Show SHA for pre-release versions on the help page
+merge_request: 22026
+author:
+type: changed

lib/gitlab.rb

@@ -47,4 +47,8 @@ module Gitlab
   def self.dev_env_or_com?
     Rails.env.development? || org? || com?
   end
+
+  def self.pre_release?
+    VERSION.include?('pre')
+  end
 end

spec/support/stub_version.rb

+# frozen_string_literal: true
+
+module StubVersion
+  def stub_version(version, revision)
+    stub_const('Gitlab::VERSION', version)
+    allow(Gitlab).to receive(:revision).and_return(revision)
+  end
+end

spec/views/help/index.html.haml_spec.rb

+# frozen_string_literal: true
+
 require 'rails_helper'
 
 describe 'help/index' do
+  include StubVersion
+
   describe 'version information' do
+    before do
+      stub_helpers
+    end
+
     it 'is hidden from guests' do
       stub_user(nil)
       stub_version('8.0.2', 'abcdefg')
-      stub_helpers
 
       render
 
@@ -13,15 +20,28 @@ describe 'help/index' do
       expect(rendered).not_to match 'abcdefg'
     end
 
-    it 'is shown to users' do
+    context 'when logged in' do
+      before do
         stub_user
+      end
+
+      it 'shows a link to the tag to users' do
         stub_version('8.0.2', 'abcdefg')
-      stub_helpers
 
         render
 
         expect(rendered).to match '8.0.2'
-      expect(rendered).to have_link('8.0.2', href: 'https://gitlab.com/gitlab-org/gitlab-ce/tags/v8.0.2')
+        expect(rendered).to have_link('8.0.2', href: %r{https://gitlab.com/gitlab-org/gitlab-(ce|ee)/tags/v8.0.2})
+      end
+
+      it 'shows a link to the commit for pre-releases' do
+        stub_version('8.0.2-pre', 'abcdefg')
+
+        render
+
+        expect(rendered).to match '8.0.2'
+        expect(rendered).to have_link('abcdefg', href: %r{https://gitlab.com/gitlab-org/gitlab-(ce|ee)/commits/abcdefg})
+      end
     end
   end
 
@@ -37,11 +57,6 @@ describe 'help/index' do
     allow(view).to receive(:user_signed_in?).and_return(user)
   end
 
-  def stub_version(version, revision)
-    stub_const('Gitlab::VERSION', version)
-    allow(Gitlab).to receive(:revision).and_return(revision)
-  end
-
   def stub_helpers
     allow(view).to receive(:markdown).and_return('')
     allow(view).to receive(:version_status_badge).and_return('')