Improve parseyaml function

* Add default value support
* Update tests

Author: Dmitry Ilyin

lib/puppet/parser/functions/parseyaml.rb

@@ -3,21 +3,20 @@
 #
 
 module Puppet::Parser::Functions
-  newfunction(:parseyaml, :type => :rvalue, :doc => <<-EOS
+  newfunction(:parseyaml, :type => :rvalue, :arity => -2, :doc => <<-EOS
 This function accepts YAML as a string and converts it into the correct
 Puppet structure.
+
+The optional second argument can be used to pass a default value that will
+be returned if the parsing of YAML string have failed.
     EOS
   ) do |arguments|
 
-    if (arguments.size != 1) then
-      raise(Puppet::ParseError, "parseyaml(): Wrong number of arguments "+
-        "given #{arguments.size} for 1")
-    end
-
     require 'yaml'
 
-    YAML::load(arguments[0])
-
+    data = YAML::load(arguments[0])
+    data = arguments[1] unless data
+    data
   end
 end
 

spec/functions/parseyaml_spec.rb

@@ -2,9 +2,12 @@
 
 describe 'parseyaml' do
   it { is_expected.not_to eq(nil) }
-  it { is_expected.to run.with_params().and_raise_error(Puppet::ParseError, /wrong number of arguments/i) }
-  it { is_expected.to run.with_params('', '').and_raise_error(Puppet::ParseError, /wrong number of arguments/i) }
+  it { is_expected.to run.with_params().and_raise_error(ArgumentError, /wrong number of arguments/i) }
   it { is_expected.to run.with_params('["one", "two", "three"]').and_return(['one', 'two', 'three']) }
+  it { is_expected.to run.with_params('', 'default_value').and_return('default_value') }
+  it { is_expected.to run.with_params('', { 'a' => '1' }).and_return({ 'a' => '1' }) }
+  it { is_expected.to run.with_params("---\na: '1'\n").and_return({ 'a' => '1' }) }
+  it { is_expected.to run.with_params("---\na: '1'\n", 'default_value').and_return({ 'a' => '1' }) }
   context 'when running on modern rubies', :unless => RUBY_VERSION == '1.8.7' do
     it { is_expected.to run.with_params('["one"').and_raise_error(Psych::SyntaxError) }
   end