Enable the rendering pipeline to be configured per-instance

app/presenters/blacklight/rendering/pipeline.rb

@@ -2,27 +2,42 @@
 
 module Blacklight
   module Rendering
-    # The field rendering pipeline
+    # The field rendering pipeline.
+    # This takes a field and it's values and transforms them through a list of
+    # operations.
     class Pipeline
-      class_attribute :operations
+      class_attribute :operations, instance_accessor: false
 
       # The ordered list of pipeline operations
       self.operations = [HelperMethod, LinkToFacet, Microdata, Join]
 
-      def initialize(values, config, document, context, options)
+      # @param values [Array] the values for the field
+      # @param config [Blacklight::Configuration::Field] the field's configuration
+      # @param document [SolrDocument] the document
+      # @param context [Object] an execution context, used to execute the  helper method in.
+      # @param operations [Array<Class>] the list of operations in this Pipeline
+      # @param options [Hash] options to pass to the processors. Typically only `:value` is used
+      def initialize(values, config, document, context, operations, options)
         @values = values
         @config = config
         @document = document
         @context = context
+        @operations = operations
         @options = options
       end
 
-      attr_reader :values, :config, :document, :context, :options
+      attr_reader :values, :config, :document, :context, :operations, :options
 
+      # @param values [Array] the values for the field
+      # @param config [Blacklight::Configuration::Field] the field's configuration
+      # @param document [SolrDocument] the document
+      # @param context [Object] an execution context, used to execute the  helper method in.
+      # @param options [Hash] options to pass to the processors. Typically only `:value` is used
       def self.render(values, config, document, context, options)
-        new(values, config, document, context, options).render
+        new(values, config, document, context, operations, options).render
       end
 
+      # Perform the processing by the pipeline
       def render
         first, *rest = *stack
         first.new(values, config, document, context, options, rest).render

spec/presenters/pipeline_spec.rb

@@ -4,11 +4,10 @@
   include Capybara::RSpecMatchers
   let(:document) { instance_double(SolrDocument) }
   let(:context) { double }
-  let(:options) { double }
-  let(:presenter) { described_class.new(values, field_config, document, context, options) }
+  let(:options) { double('options') }
 
-  describe "render" do
-    subject { presenter.render }
+  describe '.render' do
+    subject { described_class.render(values, field_config, document, context, options) }
 
     let(:values) { %w[a b] }
     let(:field_config) { Blacklight::Configuration::NullField.new }
@@ -28,9 +27,16 @@
 
       it { is_expected.to have_selector("span[@itemprop='some-prop']", text: "a") }
     end
+
+    it 'sets the operations on the instance as equal to the class variable' do
+      expect(described_class).to receive(:new)
+        .with(values, field_config, document, context, described_class.operations, options)
+        .and_return(instance_double(described_class, render: true))
+      subject
+    end
   end
 
-  describe "#operations" do
+  describe '.operations' do
     subject { described_class.operations }
 
     it {
@@ -40,4 +46,17 @@
                          Blacklight::Rendering::Join]
     }
   end
+
+  describe '#operations' do
+    subject(:operations) { presenter.operations }
+
+    let(:presenter) { described_class.new(values, field_config, document, context, steps, options) }
+    let(:steps) { [Blacklight::Rendering::HelperMethod] }
+    let(:values) { ['a'] }
+    let(:field_config) { Blacklight::Configuration::NullField.new }
+
+    it 'sets the operations to the value passed to the initializer' do
+      expect(operations).to eq steps
+    end
+  end
 end