Do not show suppliers with no products in stock

app/models/spree/supplier.rb

@@ -12,6 +12,17 @@ module Spree
     after_initialize :initialize_country
     before_validation :set_unused_address_fields
 
+    def has_products_on_hand?
+      self.products.where('count_on_hand > 0').present?
+    end
+
+    def to_param
+      "#{id}-#{name.parameterize}"
+    end
+
+
+    private
+
     def initialize_country
       self.address ||= Address.new
       self.address.country = Country.find_by_id(Spree::Config[:default_country_id]) if self.address.new_record?
@@ -21,8 +32,5 @@ module Spree
       address.firstname = address.lastname = address.phone = 'unused' if address.present?
     end
 
-    def to_param
-      "#{id}-#{name.parameterize}"
-    end
   end
 end

app/views/spree/products/_source_sidebar.html.haml

@@ -2,7 +2,8 @@
   %h6.filter_name Shop by Supplier
   %ul.filter_choices
     - @suppliers.each do |supplier|
-      %li.nowrap= link_to supplier.name, supplier
+      - if supplier.has_products_on_hand?
+        %li.nowrap= link_to supplier.name, supplier
 
   %h6.filter_name Shop by Distributor
   %ul.filter_choices

spec/models/suppliers_spec.rb

@@ -8,14 +8,32 @@ module Spree
       it { should belong_to(:address) }
     end
 
-    it "should default country to system country" do
-      supplier = Supplier.new
-      supplier.address.country.should == Country.find_by_id(Config[:default_country_id])
-    end
-
     describe "validations" do
       it { should validate_presence_of(:name) }
     end
 
+    it "should default country to system country" do
+      subject.address.country.should == Country.find_by_id(Config[:default_country_id])
+    end
+
+    context "has_products_on_hand?" do
+      before :each do
+        @supplier = create(:supplier)
+      end
+
+      it "returns false when no products" do
+        @supplier.should_not have_products_on_hand
+      end
+
+      it "returns false when the product is out of stock" do
+        create(:product, :supplier => @supplier, :on_hand => 0)
+        @supplier.should_not have_products_on_hand
+      end
+
+      it "returns true when the product is in stock" do
+        create(:product, :supplier => @supplier, :on_hand => 1)
+        @supplier.should have_products_on_hand
+      end
+    end
   end
 end

spec/requests/consumer/suppliers_spec.rb

@@ -14,11 +14,17 @@ feature %q{
     s2 = create(:supplier)
     s3 = create(:supplier)
 
+    # And some of those suppliers have a product
+    create(:product, :supplier => s1)
+    create(:product, :supplier => s3)
+
     # When I go to the home page
     visit spree.root_path
 
-    # Then I should see a list containing all the suppliers
-    [s1, s2, s3].each { |s| page.should have_selector 'a', :text => s.name }
+    # Then I should see a list containing all the suppliers that have products in stock
+    page.should have_selector 'a', :text => s1.name
+    page.should have_selector 'a', :text => s3.name
+    page.should_not have_selector 'a', :text => s2.name
   end
 
   scenario "viewing products provided by a supplier" do