Array comparison spec

lib/hash_diff/comparison.rb

@@ -67,7 +67,7 @@ def report_difference(key, reporter)
       if comparable_hash?(key)
         self.class.new(left[key], right[key]).find_differences(&reporter)
       elsif comparable_array?(key)
-        self.class.new(left[key], right[key]).find_differences(&reporter)        
+        self.class.new(left[key], right[key]).find_differences(&reporter)
       else
         reporter.call(
           value_with_default(left, key),
@@ -77,7 +77,7 @@ def report_difference(key, reporter)
     end
 
     def value_with_default(obj, key)
-      obj[key] || NO_VALUE
+      obj.fetch(key, NO_VALUE)
     end
   end
 end

spec/hash_diff/array_comparison_spec.rb

@@ -0,0 +1,78 @@
+require "spec_helper"
+
+describe HashDiff::Comparison do
+  let(:left) {
+    [
+      {
+        foo: 'bar',
+        bar: 'foo',
+      },
+      {
+        nested: {
+          foo: 'bar',
+          bar: {
+            one: 'foo1'
+          }
+        },
+      },
+      {
+        num: 1,
+        word: nil
+      }
+    ]
+  }
+
+  def comparison(to_compare)
+    HashDiff::Comparison.new(left, to_compare)
+  end
+
+  def right
+    [
+      {
+        foo: 'bar',
+        bar: 'foo',
+      },
+      {
+        nested: {
+          foo: 'bar',
+          bar: {
+            one: 'foo1'
+          }
+        },
+      },
+      {
+        num: 1,
+        word: nil
+      }
+    ]
+  end
+
+  describe 'when arrays are the same' do
+    it 'properly determines equality' do
+      expect(comparison(right).diff).to be_empty
+    end
+
+    it 'handles empty arrays' do
+      expect(HashDiff::Comparison.new([], []).diff).to be_empty
+    end
+  end
+
+  describe 'when arrays are different' do
+    it 'reports arrays as not equal with a different order' do
+      # move an item from the end to the beginning
+      right_shuffled = right
+      popped = right_shuffled.pop
+      right_shuffled.unshift(popped)
+
+      expect(comparison(right_shuffled).diff).to_not be_empty
+    end
+
+    it 'should a deep comparison' do
+      right_with_extra_nested_element = right
+      right_with_extra_nested_element[1][:nested][:bar][:two] = 'two'
+
+      expect(comparison(right_with_extra_nested_element).diff).to_not be_empty
+    end
+  end
+
+end