Add pre commit hook for ERB Lint

config/default.yml

@@ -275,6 +275,13 @@ PreCommit:
       - '**/*.ex'
       - '**/*.exs'
 
+  ErbLint:
+    enabled: false
+    description: 'Analyze with ERB Lint'
+    required_executable: 'erblint'
+    install_command: 'bundle install erb_lint'
+    include: '**/*.html.erb'
+
   EsLint:
     enabled: false
     description: 'Analyze with ESLint'

lib/overcommit/hook/pre_commit/erb_lint.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+module Overcommit::Hook::PreCommit
+  # Runs `erblint` against any modified ERB files.
+  #
+  # @see https://github.com/Shopify/erb-lint
+  class ErbLint < Base
+    MESSAGE_REGEX = /(?<message>.+)\nIn file: (?<file>.+):(?<line>\d+)/
+
+    def run
+      result = execute(command, args: applicable_files)
+      return :pass if result.success?
+
+      extract_messages(
+        result.stdout.split("\n\n")[1..-1],
+        MESSAGE_REGEX
+      )
+    end
+  end
+end

spec/overcommit/hook/pre_commit/erb_lint_spec.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Overcommit::Hook::PreCommit::ErbLint do
+  let(:config) { Overcommit::ConfigurationLoader.default_configuration }
+  let(:context) { double('context') }
+  subject { described_class.new(config, context) }
+
+  before do
+    subject.stub(:applicable_files).and_return(%w[file1.html.erb file2.html.erb])
+  end
+
+  context 'when erblint exits successfully' do
+    before do
+      result = double('result')
+      result.stub(:success?).and_return(true)
+      subject.stub(:execute).and_return(result)
+    end
+
+    it { should pass }
+  end
+
+  context 'when erblint exits unsucessfully' do
+    let(:result) { double('result') }
+
+    before do
+      result.stub(:success?).and_return(false)
+      subject.stub(:execute).and_return(result)
+    end
+
+    context 'and it reports an error' do
+      before do
+        result.stub(:stdout).and_return(<<-MSG)
+Linting 1 files with 14 linters...
+
+erb interpolation with '<%= (...).html_safe %>' in this context is never safe
+In file: app/views/posts/show.html.erb:10
+MSG
+      end
+
+      it { should fail_hook }
+    end
+  end
+end