let resources set a base namespace for providers

Author: danielsdeleo

chef/lib/chef/resource.rb

@@ -87,15 +87,7 @@ def supports(args={})
 
     def provider(arg=nil)
       klass = if arg.kind_of?(String) || arg.kind_of?(Symbol)
-                begin
-                  Chef::Provider.const_get(convert_to_class_name(arg.to_s))
-                rescue NameError => e
-                  if e.to_s =~ /Chef::Provider/
-                    raise ArgumentError, "No provider found to match '#{arg}'"
-                  else
-                    raise e
-                  end
-                end
+                lookup_provider_constant(arg)
               else
                 arg
               end
@@ -241,6 +233,7 @@ def run_action(action)
     end
 
     class << self
+      
       def json_create(o)
         resource = self.new(o["instance_vars"]["@name"])
         o["instance_vars"].each do |k,v|
@@ -306,9 +299,34 @@ def actions_to_create
 
         new_resource_class
       end
+      
+      # Resources that want providers namespaced somewhere other than 
+      # Chef::Provider can set the namespace with +provider_base+
+      # Ex:
+      #   class MyResource < Chef::Resource
+      #     provider_base Chef::Provider::Deploy
+      #     # ...other stuff
+      #   end
+      def provider_base(arg=nil)
+        @provider_base ||= arg
+        @provider_base ||= Chef::Provider
+      end
+      
     end
 
     private
+    
+      def lookup_provider_constant(name)
+        begin
+          self.class.provider_base.const_get(convert_to_class_name(name.to_s))
+        rescue NameError => e
+          if e.to_s =~ /#{self.class.provider_base.to_s}/
+            raise ArgumentError, "No provider found to match '#{name}'"
+          else
+            raise e
+          end
+        end
+      end
 
       def check_timing(timing)
         unless timing == :delayed || timing == :immediate || timing == :immediately

chef/spec/unit/resource_spec.rb

@@ -18,6 +18,10 @@
 
 require File.expand_path(File.join(File.dirname(__FILE__), "..", "spec_helper"))
 
+class ResourceTestHarness < Chef::Resource
+  provider_base Chef::Provider::Package
+end
+
 describe Chef::Resource do
   before(:each) do
     @resource = Chef::Resource.new("funk")
@@ -211,4 +215,16 @@
     end
   end
 
+  describe "setting the base provider class for the resource" do
+    
+    it "defaults to Chef::Provider for the base class" do
+      Chef::Resource.provider_base.should == Chef::Provider
+    end
+    
+    it "allows the base provider to be overriden by a " do
+      ResourceTestHarness.provider_base.should == Chef::Provider::Package
+    end
+    
+  end
+  
 end