1 files changed, 5 insertions, 3 deletions
diff --git a/activesupport/lib/active_support/testing/assertions.rb b/activesupport/lib/active_support/testing/assertions.rb
index 3864b1f5a6..f3629ada5b 100644
--- a/activesupport/lib/active_support/testing/assertions.rb
+++ b/activesupport/lib/active_support/testing/assertions.rb
@@ -45,15 +45,17 @@ module ActiveSupport
       #     post :delete, :id => ...
       #   end
       def assert_difference(expression, difference = 1, message = nil, &block)
-        exps = Array.wrap(expression).map { |e|
+        expressions = Array.wrap expression
+
+        exps = expressions.map { |e|
           e.respond_to?(:call) ? e : lambda { eval(e, block.binding) }
         }
         before = exps.map { |e| e.call }
 
         yield
 
-        exps.each_with_index do |e, i|
-          error  = "#{e.inspect} didn't change by #{difference}"
+        expressions.zip(exps).each_with_index do |(code, e), i|
+          error  = "#{code.inspect} didn't change by #{difference}"
           error  = "#{message}.\n#{error}" if message
           assert_equal(before[i] + difference, e.call, error)
         end