Merge pull request #518 from mbj/fix/diff-coverage

Fix Mutant::Diff coverage

config/flay.yml

@@ -1,3 +1,3 @@
 ---
 threshold: 18
-total_score: 1175
+total_score: 1171

lib/mutant/diff.rb

@@ -17,9 +17,7 @@ module Mutant
     def diff
       return if diffs.empty?
 
-      minimized_hunks.map do |hunk|
-        hunk.diff(:unified) << NEWLINE
-      end.join
+      minimized_hunk.diff(:unified) << NEWLINE
     end
     memoize :diff
 
@@ -74,19 +72,15 @@ module Mutant
       end
     end
 
-    # Minimized hunks
+    # Minimized hunk
     #
-    # @return [Array<Diff::LCS::Hunk>]
-    def minimized_hunks
+    # @return Diff::LCS::Hunk
+    def minimized_hunk
       head, *tail = hunks
 
-      tail.each_with_object([head]) do |right, aggregate|
-        left = aggregate.last
-        if right.overlaps?(left)
+      tail.reduce(head) do |left, right|
         right.merge(left)
-          aggregate.pop
-        end
-        aggregate << right
+        right
       end
     end
 

spec/unit/mutant/diff_spec.rb

@@ -34,6 +34,15 @@ RSpec.describe Mutant::Diff do
 
       it_should_behave_like 'an idempotent method'
     end
+
+    context 'when there is no diff' do
+      let(:old) { '' }
+      let(:new) { '' }
+
+      it { should be(nil) }
+
+      it_should_behave_like 'an idempotent method'
+    end
   end
 
   describe '#diff' do