Handle diff method being initialized with an instance of itself

Author: Kevin Paulisse

lib/octocatalog-diff/api/v1/diff.rb

@@ -22,8 +22,13 @@ class Diff
         # Constructor: Accepts a diff in the traditional array format and stores it.
         # @param raw [Array] Diff in the traditional format
         def initialize(raw)
+          if raw.is_a?(OctocatalogDiff::API::V1::Diff)
+            @raw = raw.raw
+            return
+          end
+
           unless raw.is_a?(Array)
-            raise ArgumentError, 'OctocatalogDiff::API::V1::Diff#initialize expects Array argument'
+            raise ArgumentError, "OctocatalogDiff::API::V1::Diff#initialize expects Array argument (got #{raw.class})"
           end
           @raw = raw
         end

spec/octocatalog-diff/tests/api/v1/diff_spec.rb

@@ -350,6 +350,12 @@
   end
 
   describe '#initialize' do
+    it 'should set up raw object when called with an instance of itself' do
+      obj1 = described_class.new(chg_2)
+      testobj = described_class.new(obj1)
+      expect(testobj.raw).to eq(chg_2)
+    end
+
     it 'should raise ArgumentError if called with a non-array' do
       expect { described_class.new('foo') }.to raise_error(ArgumentError)
     end