Add initial implementation of post-commit hooks

Change-Id: I232175d2fcdd54ca2cbda05a20eb9d7d2acc1a46
Reviewed-on: http://gerrit.causes.com/46923
Tested-by: jenkins <jenkins@brigade.com>
Reviewed-by: Shane da Silva <shane.dasilva@brigade.com>

Author: jawshooah

config/default.yml

@@ -292,3 +292,9 @@ CommitMsg:
 
   TrailingPeriod:
     description: 'Checking for trailing periods in subject'
+
+PostCommit:
+  ALL:
+    requires_files: false
+    required: false
+    quiet: false

lib/overcommit/git_repo.rb

@@ -21,6 +21,7 @@ def extract_modified_lines(file_path, options)
       refs = options[:refs]
 
       flags = '--cached' if options[:staged]
+      refs  = options[:refs]
 
       `git diff --no-ext-diff -U0 #{flags} #{refs} -- #{file_path}`.
         scan(DIFF_HUNK_REGEX) do |start_line, lines_added|

lib/overcommit/hook/post_commit/base.rb

@@ -0,0 +1,10 @@
+require 'forwardable'
+
+module Overcommit::Hook::PostCommit
+  # Functionality common to all post-commit hooks.
+  class Base < Overcommit::Hook::Base
+    extend Forwardable
+
+    def_delegators :@context, :modified_lines_in_file
+  end
+end

lib/overcommit/hook_context/post_commit.rb

@@ -0,0 +1,20 @@
+module Overcommit::HookContext
+  # Contains helpers related to contextual information used by post-commit
+  # hooks.
+  class PostCommit < Base
+    # Get a list of files that were added, copied, or modified in the last
+    # commit. Renames and deletions are ignored, since there should be nothing
+    # to check.
+    def modified_files
+      @modified_files ||= Overcommit::GitRepo.modified_files(refs: 'HEAD~ HEAD')
+    end
+
+    # Returns the set of line numbers corresponding to the lines that were
+    # changed in a specified file.
+    def modified_lines_in_file(file)
+      @modified_lines ||= {}
+      @modified_lines[file] ||=
+        Overcommit::GitRepo.extract_modified_lines(file, refs: 'HEAD~ HEAD')
+    end
+  end
+end

spec/overcommit/utils_spec.rb

@@ -108,13 +108,13 @@
   describe '.supported_hook_types' do
     subject { described_class.supported_hook_types }
 
-    it { should =~ %w[commit-msg pre-commit post-checkout post-merge] }
+    it { should =~ %w[commit-msg pre-commit post-checkout post-commit post-merge] }
   end
 
   describe '.supported_hook_type_classes' do
     subject { described_class.supported_hook_type_classes }
 
-    it { should =~ %w[CommitMsg PreCommit PostCheckout PostMerge] }
+    it { should =~ %w[CommitMsg PreCommit PostCheckout PostCommit PostMerge] }
   end
 
   describe '.execute' do

template-dir/hooks/post-commit

@@ -0,0 +1,81 @@
+#!/usr/bin/env ruby
+
+# Entrypoint for Overcommit hook integration. Installing Overcommit will result
+# in all of your git hooks being symlinked to this file, allowing the framework
+# to manage your hooks for you.
+
+# Prevent a Ruby stack trace from appearing when we interrupt the hook.
+# Note that this will be overridden when Overcommit is loaded, since the
+# InterruptHandler will redefine the trap at that time.
+Signal.trap('INT') do
+  puts 'Hook run interrupted'
+  exit 130
+end
+
+# Allow hooks to be disabled via environment variable so git commands can be run
+# in scripts without Overcommit running hooks
+if ENV['OVERCOMMIT_DISABLE'].to_i != 0 || ENV['OVERCOMMIT_DISABLED'].to_i != 0
+  exit
+end
+
+hook_type = File.basename($0)
+if hook_type == 'overcommit-hook'
+  puts "Don't run `overcommit-hook` directly; it is intended to be symlinked " \
+       "by each hook in a repository's .git/hooks directory."
+  exit 64 # EX_USAGE
+end
+
+begin
+  require 'overcommit'
+rescue LoadError
+  puts 'This repository contains hooks installed by Overcommit, but the ' \
+       "overcommit gem is not installed.\n" \
+       'Install it with `gem install overcommit`.'
+  exit
+end
+
+begin
+  logger = Overcommit::Logger.new(STDOUT)
+
+  # Ensure master hook is up-to-date
+  installer = Overcommit::Installer.new(logger)
+  if installer.run(Overcommit::Utils.repo_root, action: :update)
+    exec($0, *ARGV) # Execute the updated hook with all original arguments
+  end
+
+  config = Overcommit::ConfigurationLoader.load_repo_config
+
+  context = Overcommit::HookContext.create(hook_type, config, ARGV)
+  config.apply_environment!(context, ENV)
+
+  printer = Overcommit::Printer.new(logger, context)
+  runner = Overcommit::HookRunner.new(config, logger, context, printer)
+
+  status = runner.run
+
+  exit(status ? 0 : 65) # 65 = EX_DATAERR
+rescue Overcommit::Exceptions::ConfigurationError => error
+  puts error
+  exit 78 # EX_CONFIG
+rescue Overcommit::Exceptions::HookContextLoadError => error
+  puts error
+  puts 'Are you running an old version of Overcommit?'
+  exit 69 # EX_UNAVAILABLE
+rescue Overcommit::Exceptions::HookSetupFailed,
+       Overcommit::Exceptions::HookCleanupFailed => error
+  puts error.message
+  exit 74 # EX_IOERR
+rescue Overcommit::Exceptions::HookCancelled
+  puts 'You cancelled the hook run'
+  exit 130 # Ctrl-C cancel
+rescue Overcommit::Exceptions::InvalidGitRepo => error
+  puts error
+  exit 64 # EX_USAGE
+rescue Overcommit::Exceptions::InvalidHookSignature
+  exit 1
+rescue => error
+  puts error.message
+  puts error.backtrace
+  puts "Report this bug at #{Overcommit::BUG_REPORT_URL}"
+  exit 70 # EX_SOFTWARE
+end