Add KeybaseDirSign pre-commit hook + tests.

config/default.yml

@@ -266,6 +266,13 @@ PreCommit:
     install_command: 'gem install json'
     include: '**/*.json'
 
+  KeybaseDirSign:
+    enabled: false
+    description: Signing directory contents with Keybase
+    required_executable: 'keybase'
+    flags: ['dir', 'sign', '--quiet']
+    install_command: 'npm install -g keybase-installer && keybase-installer'
+
   LocalPathsInGemfile:
     enabled: false
     description: 'Checking for local paths in Gemfile'

lib/overcommit/hook/pre_commit/keybase_dir_sign.rb

@@ -0,0 +1,25 @@
+module Overcommit::Hook::PreCommit
+  # Runs `keybase dir sign` and `git add SIGNED.md` to sign the dir contents
+  # with an OpenPGP cryptographic signature. Signs *all* files, not just
+  # those that are part of the current commit.
+  #
+  # @see https://keybase.io/
+  class KeybaseDirSign < Base
+    def run
+      keybase_result = execute(command)
+      keybase_output = keybase_result.stdout.chomp
+
+      if keybase_result.success? && keybase_output.empty?
+        git_result = execute(['git', 'add', 'SIGNED.md'])
+        git_output = git_result.stdout.chomp
+
+        if git_result.success? && git_output.empty?
+          return :pass
+        end
+        [:fail, git_result.stderr]
+      end
+
+      [:fail, keybase_result.stderr]
+    end
+  end
+end

spec/overcommit/hook/pre_commit/keybase_dir_sign_spec.rb

@@ -0,0 +1,38 @@
+require 'spec_helper'
+
+describe Overcommit::Hook::PreCommit::KeybaseDirSign do
+  let(:config)  { Overcommit::ConfigurationLoader.default_configuration }
+  let(:context) { double('context') }
+  subject { described_class.new(config, context) }
+
+  context 'when keybase exits successfully' do
+    before do
+      result = double('result')
+      result.stub(:success?).and_return(true)
+      result.stub(:stdout).and_return('')
+      subject.stub(:execute).and_return(result)
+    end
+
+    it { should pass }
+  end
+
+  context 'when keybase exits unsucessfully' do
+    let(:result) { double('result') }
+
+    before do
+      result.stub(:success?).and_return(false)
+      result.stub(:stdout).and_return('')
+      subject.stub(:execute).and_return(result)
+    end
+
+    context 'and it reports an error' do
+      before do
+        result.stub(:stderr).and_return([
+          'an error'
+        ].join('\n'))
+      end
+
+      it { should fail_hook }
+    end
+  end
+end