mysql_deepmerge should treat underscore and dash equivalently, as mysql does

lib/puppet/parser/functions/mysql_deepmerge.rb

@@ -12,6 +12,8 @@ module Puppet::Parser::Functions
 
     When there is a duplicate key that is a hash, they are recursively merged.
     When there is a duplicate key that is not a hash, the key in the rightmost hash will "win."
+    When there are conficting uses of dashes and underscores in two keys (which mysql would otherwise equate),
+      the rightmost style will win.
 
     ENDHEREDOC
 
@@ -36,17 +38,21 @@ module Puppet::Parser::Functions
   end
 end
 
-def overlay( hash1, hash2 )
-    hash2.each do |key, value|
-        if( value.is_a?(Hash) )
-            if( ! hash1.has_key?( key ) or ! hash1[key].is_a?(Hash))
-                hash1[key] = value
-            else
-                overlay( hash1[key], value )
-            end
-        else
-            hash1[key] = value
-        end
-    end
+def has_normalized!(hash, key)
+  return true if hash.has_key?( key )
+  return false unless key.match(/-|_/)
+  other_key = key.include?('-') ? key.gsub( '-', '_' ) : key.gsub( '_', '-' )
+  return false unless hash.has_key?( other_key )
+  hash[key] = hash.delete( other_key )
+  return true;
 end
 
+def overlay( hash1, hash2 )
+  hash2.each do |key, value|
+    if(has_normalized!( hash1, key ) and value.is_a?(Hash) and hash1[key].is_a?(Hash))
+      overlay( hash1[key], value )
+    else
+      hash1[key] = value
+    end
+  end
+end

spec/unit/puppet/functions/mysql_deepmerge_spec.rb

@@ -73,5 +73,19 @@ describe Puppet::Parser::Functions.function(:mysql_deepmerge) do
       hash['key1'].should == { 'a' => 1, 'b' => 99 }
       hash['key2'].should == { 'c' => 3 }
     end
+
+    it 'should equate keys mod dash and underscore' do
+      hash = scope.function_mysql_deepmerge([{  'a-b-c' => 1 } , { 'a_b_c' => 10 }])
+      hash['a_b_c'].should == 10
+      hash.should_not have_key('a-b-c')
+    end
+
+    it 'should keep style of the last when keys are euqal mod dash and underscore' do
+      hash = scope.function_mysql_deepmerge([{  'a-b-c' => 1,  'b_c_d' => { 'c-d-e' => 2, 'e-f-g' => 3 }} , { 'a_b_c' => 10, 'b-c-d' => { 'c_d_e' => 12 } }])
+      hash['a_b_c'].should == 10
+      hash.should_not have_key('a-b-c')
+      hash['b-c-d'].should == { 'e-f-g' => 3, 'c_d_e' => 12 }
+      hash.should_not have_key('b_c_d')
+    end
   end
 end