Merge pull request #934 from nanoc/gh-932-filter-define-assigns

Fix assigns in filters defined with Filter.define

lib/nanoc/base/compilation/filter.rb

@@ -38,10 +38,10 @@ class Filter < Nanoc::Int::Context
     extend Nanoc::Int::PluginRegistry::PluginMethods
 
     class << self
-      def define(ident)
+      def define(ident, &block)
         filter_class = Class.new(::Nanoc::Filter) { identifier(ident) }
         filter_class.send(:define_method, :run) do |content, params|
-          yield(content, params)
+          instance_exec(content, params, &block)
         end
       end
 

spec/nanoc/base/filter_spec.rb

@@ -1,17 +1,39 @@
 describe Nanoc::Filter do
   describe '.define' do
-    before do
-      Nanoc::Filter.define(:nanoc_filter_define_sample) do |content, _params|
-        content.upcase
+    context 'simple filter' do
+      let(:filter_name) { 'b5355bbb4d772b9853d21be57da614dba521dbbb' }
+      let(:filter_class) { Nanoc::Filter.named(filter_name) }
+
+      before do
+        Nanoc::Filter.define(filter_name) do |content, _params|
+          content.upcase
+        end
       end
-    end
 
-    it 'defines a filter' do
-      expect(Nanoc::Filter.named(:nanoc_filter_define_sample)).not_to be_nil
+      it 'defines a filter' do
+        expect(filter_class).not_to be_nil
+      end
+
+      it 'defines a callable filter' do
+        expect(filter_class.new.run('foo', {})).to eql('FOO')
+      end
     end
 
-    it 'defines a callable filter' do
-      expect(Nanoc::Filter.named(:nanoc_filter_define_sample).new.run('foo', {})).to eql('FOO')
+    context 'filter that accesses assigns' do
+      let(:filter_name) { 'd7ed105d460e99a3d38f46af023d9490c140fdd9' }
+      let(:filter_class) { Nanoc::Filter.named(filter_name) }
+      let(:filter) { filter_class.new(assigns) }
+      let(:assigns) { { animal: 'Giraffe' } }
+
+      before do
+        Nanoc::Filter.define(filter_name) do |_content, _params|
+          @animal
+        end
+      end
+
+      it 'can access assigns' do
+        expect(filter.setup_and_run(:__irrelevant__, {})).to eq('Giraffe')
+      end
     end
   end
 end