(MAINT) Add acceptance tests

This commit adds the first batch of acceptance tests for puppet-lint.

The next step in the process will be to examinethe realease_tests rake
task and migrate any relevant tests across to the new acceptance suite.

Author: chelnak

spec/acceptance/puppet_lint_spec.rb

@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+require 'spec_helper_acceptance'
+
+describe 'When executing puppet-lint' do
+  let(:manifest_root) { File.join(File.dirname(__FILE__), '..', 'fixtures', 'test', 'manifests') }
+
+  context 'with no manifest provided' do
+    it 'returns an exit code of 1 with no arguments' do
+      result = puppet_lint
+      expect(result[:exit_code]).to eq(1)
+    end
+
+    it 'returns an exit code of 0 when given a single flag' do
+      result = puppet_lint(['--help'])
+      expect(result[:exit_code]).to eq(0)
+    end
+
+    it 'returns the correct version number with the --version flag' do
+      result = puppet_lint(['--version'])
+      expect(result[:stdout]).to match(PuppetLint::VERSION)
+    end
+  end
+
+  context 'with a manifest provided' do
+    it 'returns one error when there is one problem' do
+      result = puppet_lint([File.join(manifest_root, 'fail.pp')])
+      expect(result[:stdout]).to have_errors(1)
+    end
+
+    it 'returns zero errors when there is an ignore comment present' do
+      result = puppet_lint([File.join(manifest_root, 'ignore.pp')])
+      expect(result[:stdout]).to have_errors(0)
+    end
+
+    it 'returns one warning when there is one problem' do
+      result = puppet_lint([File.join(manifest_root, 'warning.pp')])
+      expect(result[:stdout]).to have_warnings(1)
+    end
+
+    it 'contains two warnings when there are two problems' do
+      result = puppet_lint([File.join(manifest_root, 'two_warnings.pp')])
+      expect(result[:stdout]).to have_warnings(2)
+    end
+  end
+end