Actually enforce apt and yum versions in the metadata.rb file (#874)

* Actually enforce apt and yum versions in the metadata.rb file

* Remove comments about apt and yum in the README.md file

* Fix typo

* Make it work for Chef < 13.1.33

* Fix style

* Fix style

Author: amenasria

README.md

@@ -42,19 +42,6 @@ The following Opscode cookbooks are dependencies:
 
 #### Chef
 
-**Chef 12 users**: Depending on your version of Chef 12, additional dependency constraints may apply:
-
-```ruby
-# Chef < 12.14
-depends 'yum', '< 5.0'
-```
-
-```ruby
-# Chef < 12.9
-depends 'apt', '< 6.0.0'
-depends 'yum', '< 5.0'
-```
-
 **Chef 13 users**: With Chef 13 and `chef_handler` 1.x, you may have trouble using the `dd-handler` recipe. The known workaround is to update your dependency to `chef_handler` >= 2.1.
 
 ### Installation

metadata.rb

@@ -22,10 +22,30 @@
   supports os
 end
 
-if Chef::VERSION < Gem::Version.new(14)
+current_chef_version = if Chef::VERSION.instance_of? String
+                         # For Chef < 13.1.33 Chef::VERSION was a String
+                         Gem::Version.new(Chef::VERSION.to_f)
+                       else
+                         # Else Chef::VERSION is already a VersionString
+                         Chef::VERSION
+                       end
+
+if current_chef_version < Gem::Version.new(14)
   # The chef_handler cookbook is shipped as part of Chef >= 14,
   # so from Chef >= 14 chef_handler cookbook is deprecated.
   depends 'chef_handler', '>= 1.2'
 end
-depends    'apt' # Use '< 6.0.0' with Chef < 12.9
-depends    'yum', '>= 3.0' # Use '< 5.0' with Chef < 12.14
+
+# Use '< 6.0.0' with Chef < 12.9
+if current_chef_version < Gem::Version.new(12.9)
+  depends 'apt', '< 6.0'
+else
+  depends 'apt'
+end
+
+# Use '< 5.0' with Chef < 12.14
+if current_chef_version < Gem::Version.new(12.14)
+  depends 'yum', '>= 3.0', '< 5.0'
+else
+  depends 'yum', '>= 3.0'
+end