Add only_if to Inspec objects (#3577)

* Add only_if attr to Inspec::test
* Add only_if attr to Inspec::Control

Signed-off-by: James Stocks <jstocks@chef.io>

lib/inspec/objects/control.rb

@@ -2,7 +2,7 @@
 
 module Inspec
   class Control
-    attr_accessor :id, :title, :descriptions, :impact, :tests, :tags, :refs
+    attr_accessor :id, :title, :descriptions, :impact, :tests, :tags, :refs, :only_if
     def initialize
       @tests = []
       @tags = []
@@ -43,6 +43,7 @@ module Inspec
       res.push "  impact #{impact}" unless impact.nil?
       tags.each { |t| res.push(indent(t.to_ruby, 2)) }
       refs.each { |t| res.push("  ref   #{print_ref(t)}") }
+      res.push "  only_if { #{only_if} }" if only_if
       tests.each { |t| res.push(indent(t.to_ruby, 2)) }
       res.push 'end'
       res.join("\n")

lib/inspec/objects/test.rb

@@ -2,7 +2,7 @@
 
 module Inspec
   class Test
-    attr_accessor :qualifier, :matcher, :expectation, :skip, :negated, :variables
+    attr_accessor :qualifier, :matcher, :expectation, :skip, :negated, :variables, :only_if
     include RubyHelper
 
     def initialize
@@ -61,6 +61,7 @@ module Inspec
     end
 
     def rb_describe
+      only_if_clause = "only_if { #{only_if} }\n" if only_if
       vars = variables.map(&:to_ruby).join("\n")
       vars += "\n" unless vars.empty?
       res, xtra = describe_chain
@@ -74,8 +75,8 @@ module Inspec
               elsif xpect != ''
                 ' ' + expectation.inspect
               end
-      format("%sdescribe %s do\n  %s { should%s %s%s }\nend",
-             vars, res, itsy, naughty, matcher, xpect)
+      format("%s%sdescribe %s do\n  %s { should%s %s%s }\nend",
+             only_if_clause, vars, res, itsy, naughty, matcher, xpect)
     end
 
     def rb_skip

test/unit/dsl/objects_test.rb

@@ -156,6 +156,19 @@ end
 describe service("avahi-daemon").info[\'properties\'][\'UnitFileState\'] do
   it { should eq "enabled" }
 end
+'.strip
+    end
+
+   it 'constructs a simple resource + only_if' do
+      obj.qualifier = [['resource'], ['version']]
+      obj.matcher = 'cmp >='
+      obj.expectation = '2.4.2'
+      obj.only_if = "package('ntp').installed?"
+      obj.to_ruby.must_equal '
+only_if { package(\'ntp\').installed? }
+describe resource do
+  its("version") { should cmp >= "2.4.2" }
+end
 '.strip
     end
   end
@@ -297,6 +310,36 @@ end
 '.strip
     end
 
+    it 'constructs a control with only_if' do
+      control = Inspec::Control.new
+      control.add_test(obj1)
+      control.only_if = "package('ntp').installed?"
+      control.id = 'sample.control.id'
+      control.title = 'Sample Control Important Title'
+      control.descriptions = {
+        default: 'The most critical control the world has ever seen',
+        rationale: 'It is needed to save the planet',
+        'more info': 'Insert clever joke here',
+      }
+      control.refs = ['simple ref', {ref: 'title', url: 'my url'}]
+      control.impact = 1.0
+      control.to_ruby.must_equal '
+control "sample.control.id" do
+  title "Sample Control Important Title"
+  desc  "The most critical control the world has ever seen"
+  desc  "rationale", "It is needed to save the planet"
+  desc  "more info", "Insert clever joke here"
+  impact 1.0
+  ref   "simple ref"
+  ref   ({:ref=>"title", :url=>"my url"})
+  only_if { package(\'ntp\').installed? }
+  describe command("ls /etc") do
+    its("exit_status") { should eq 0 }
+  end
+end
+'.strip
+    end
+
     it 'constructs a multiline desc in a control with indentation' do
       control = Inspec::Control.new
       control.descriptions[:default] = "Multiline\n  control"