Adds ActiveFedora::Checksum class to encapsulate file digest info.

lib/active_fedora.rb

@@ -49,6 +49,7 @@ module ActiveFedora #:nodoc:
     autoload :CachingConnection
     autoload :Callbacks
     autoload :ChangeSet
+    autoload :Checksum
     autoload :CleanConnection
     autoload :Config
     autoload :Core

lib/active_fedora/checksum.rb

@@ -0,0 +1,15 @@
+module ActiveFedora
+  class Checksum
+
+    attr_reader :uri, :value, :algorithm
+
+    def initialize(file)
+      @uri = file.digest.first
+      if @uri
+        @algorithm, @value = @uri.path.split(":")
+        @algorithm.upcase!
+      end
+    end
+
+  end
+end

lib/active_fedora/file.rb

@@ -134,6 +134,10 @@ def metadata
       @metadata ||= ActiveFedora::WithMetadata::MetadataNode.new(self)
     end
 
+    def checksum
+      ActiveFedora::Checksum.new(self)
+    end
+
     def content_changed?
       return true if new_record? and !local_or_remote_content(false).blank?
       local_or_remote_content(false) != @ds_content

spec/unit/checksum_spec.rb

@@ -0,0 +1,27 @@
+require "spec_helper"
+
+module ActiveFedora
+  describe Checksum do
+
+    subject { described_class.new(file) }
+
+    let(:uri) { ::RDF::URI("urn:sha1:bb3200c2ddaee4bd7b9a4dc1ad3e10ed886eaef1") }
+
+    describe "when initialized with a file having a digest" do
+      let(:file) { double(digest: [uri]) }
+
+      its(:uri) { is_expected.to eq(uri) }
+      its(:value) { is_expected.to eq("bb3200c2ddaee4bd7b9a4dc1ad3e10ed886eaef1") }
+      its(:algorithm) { is_expected.to eq("SHA1") }
+    end
+
+    describe "when initialized with a file not having a digest" do
+      let(:file) { double(digest: []) }
+
+      its(:uri) { is_expected.to be_nil }
+      its(:value) { is_expected.to be_nil }
+      its(:algorithm) { is_expected.to be_nil }
+    end
+
+  end
+end

spec/unit/file_spec.rb

@@ -258,6 +258,20 @@
     end
   end
 
+  describe "#checksum" do
+    let(:digest) { RDF::URI.new("urn:sha1:f1d2d2f924e986ac86fdf7b36c94bcdf32beec15") }
+    before do
+      allow(subject).to receive(:digest) { [digest] }
+    end
+    its(:checksum) { is_expected.to be_a(ActiveFedora::Checksum) }
+    it "should have the right value" do
+      expect(subject.checksum.value).to eq("f1d2d2f924e986ac86fdf7b36c94bcdf32beec15")
+    end
+    it "should have the right algorithm" do
+      expect(subject.checksum.algorithm).to eq("SHA1")
+    end
+  end
+
   describe "#save" do
     let(:file) { described_class.new }
     context "when there is nothing to save" do