Merge pull request shakacode#125 from robwise/display-commit

Add current Git commit hash to view

Author: justin808

Diff for: .buildpacks

@@ -1,2 +1,3 @@
 https://github.com/heroku/heroku-buildpack-nodejs.git
 https://github.com/heroku/heroku-buildpack-ruby.git
+https://github.com/sreid/heroku-buildpack-sourceversion.git

Diff for: app/helpers/pages_helper.rb

@@ -1,2 +1,10 @@
 module PagesHelper
+  def git_commit_sha
+    GitCommitSha.current_sha
+  end
+
+  def git_commit_sha_short
+    full_sha = git_commit_sha
+    full_sha[-7..-1]
+  end
 end

Diff for: app/models/git_commit_sha.rb

@@ -0,0 +1,25 @@
+# Retrieves the current git commit SHA of the project
+class GitCommitSha
+  def self.current_sha
+    @sha ||= retrieve_sha_from_file.presence || retrieve_sha_from_git
+  end
+
+  def self.current_sha=(sha)
+    @sha = sha
+  end
+
+  def self.reset_current_sha
+    self.current_sha = nil
+  end
+
+  # Assumes the git CLI is available. This is not the case in production on Heroku.
+  def self.retrieve_sha_from_git
+    `git rev-parse HEAD 2>/dev/null`.to_s.strip
+  end
+
+  # Assumes a .source_version file with SHA inside. A special Heroku buildpack creates this for us in production.
+  def self.retrieve_sha_from_file
+    expected_filepath = Rails.root.join(".source_version")
+    File.exist?(expected_filepath) ? File.read(expected_filepath).to_s.strip : nil
+  end
+end

Diff for: app/views/pages/index.html.erb

@@ -1,4 +1,9 @@
 <h2>Using React + Redux + Rails Backend (using the react_on_rails gem)</h2>
+<p>Current Commit:
+  <%= link_to git_commit_sha_short,
+      "https://github.com/shakacode/react-webpack-rails-tutorial/commit/#{git_commit_sha}",
+      id: "git-commit-sha" %>
+</p>
 <ul>
   <li>
     If this work interests you and you're a developer or designer looking for full or part-time remote work: please

Diff for: spec/features/pages_spec.rb

@@ -0,0 +1,34 @@
+require "rails_helper"
+
+shared_examples "Git Commit SHA" do
+  background { visit root_path }
+  it "displays the current git commit" do
+    el = find("#git-commit-sha")
+    expect(el.text).to eq expected_text
+  end
+end
+
+feature "Git Commit SHA" do
+  before do
+    # sha gets cached as an instance variable, so need to start fresh
+    GitCommitSha.reset_current_sha
+  end
+
+  context "when .source_version file does not exist" do
+    let(:sha) { "94d92356828a56db25fccff9d50f41c525eead5x" }
+    let(:expected_text) { "5eead5x" }
+    before do
+      # stub this method since we need to control what the sha actually is
+      allow(GitCommitSha).to receive(:retrieve_sha_from_git) { sha }
+    end
+    it_behaves_like "Git Commit SHA"
+  end
+
+  context "when .source_version file exists" do
+    let(:sha) { "94d92356828a56db25fccff9d50f41c525eead5y" }
+    let(:expected_text) { "5eead5y" }
+    before { `cd #{Rails.root} && echo #{sha} > .source_version` }
+    after { `cd #{Rails.root} && rm .source_version` }
+    it_behaves_like "Git Commit SHA"
+  end
+end