if AnyArgMatcher is defined, diff_hashes_as_object folds anything

lib/rspec/support/differ.rb

@@ -59,10 +59,25 @@ def diff_as_string(actual, expected)
       # rubocop:enable Metrics/MethodLength
 
       def diff_hashes_as_object(actual, expected)
-        expected.select { |_, v| RSpec::Mocks::ArgumentMatchers::AnyArgMatcher === v }.each_key do |k|
-          expected[k] = actual[k]
+        if defined?(RSpec::Mocks::ArgumentMatchers::AnyArgMatcher)
+          anything_hash = expected.select { |_, v| RSpec::Mocks::ArgumentMatchers::AnyArgMatcher === v }
+
+          anything_hash.each_key do |k|
+            expected[k] = actual[k]
+          end
+
+          diff_string = diff_as_object(actual, expected)
+
+          if defined?(RSpec::Mocks::ArgumentMatchers::AnyArgMatcher)
+            anything_hash.each do |k, v|
+              expected[k] = v
+            end
+          end
+
+          diff_string
+        else
+          diff_as_object(actual, expected)
         end
-        diff_as_object(actual, expected)
       end
 
       def diff_as_object(actual, expected)

spec/rspec/support/differ_spec.rb

@@ -572,6 +572,12 @@ def inspect; "<BrokenObject>"; end
             EOD
             expect(diff).to be_diffed_as(expected_diff)
           end
+          it "checks the 'expected' var continues having the 'anything' fuzzy matcher, it has not mutated" do
+            actual = { :fixed => "fixed", :trigger => "trigger", :anything_key => "bcdd0399-1cfe-4de1-a481-ca6b17d41ed8" }
+            expected = { :fixed => "fixed", :trigger => "wrong", :anything_key => anything }
+            differ.diff(actual, expected)
+            expect(expected).to eq({ :fixed => "fixed", :trigger => "wrong", :anything_key => anything })
+          end
         end
       end
     end