Enhance assert_difference to accept arrays of strings which are then evaled

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6926 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

2 files changed, 21 insertions, 6 deletions

diff --git a/activesupport/lib/active_support/core_ext/test/difference.rb b/activesupport/lib/active_support/core_ext/test/difference.rb
index 17cac8919d..05eab30603 100644
--- a/activesupport/lib/active_support/core_ext/test/difference.rb
+++ b/activesupport/lib/active_support/core_ext/test/difference.rb
@@ -19,11 +19,20 @@ module Test #:nodoc:
       #   assert_difference 'Article.count', -1 do
       #     post :delete, :id => ...
       #   end
-      def assert_difference(expression, difference = 1, &block)
-        expression_evaluation = lambda { eval(expression, block.binding) }
-        original_value        = expression_evaluation.call
+      #
+      # An array of expressions can also be passed in and evaluated.
+      #
+      #   assert_difference [ 'Article.count', 'Post.count' ], +2 do
+      #     post :create, :article => {...}
+      #   end
+      def assert_difference(expressions, difference = 1, &block)
+        expression_evaluations = [expressions].flatten.collect{|expression| lambda { eval(expression, block.binding) } } 
+        
+        original_values = expression_evaluations.inject([]) { |memo, expression| memo << expression.call }
         yield
-        assert_equal original_value + difference, expression_evaluation.call
+        expression_evaluations.each_with_index do |expression, i|
+          assert_equal original_values[i] + difference, expression.call
+        end
       end
 
       # Assertion that the numeric result of evaluating an expression is not changed before and after
@@ -32,8 +41,8 @@ module Test #:nodoc:
       #   assert_no_difference 'Article.count' do
       #     post :create, :article => invalid_attributes
       #   end
-      def assert_no_difference(expression, &block)
-        assert_difference expression, 0, &block
+      def assert_no_difference(expressions, &block)
+        assert_difference expressions, 0, &block
       end
     end
   end
diff --git a/activesupport/test/test_test.rb b/activesupport/test/test_test.rb
index b1d916d5c0..944b98f529 100644
--- a/activesupport/test/test_test.rb
+++ b/activesupport/test/test_test.rb
@@ -53,4 +53,10 @@ class AssertDifferenceTest < Test::Unit::TestCase
       assert_difference('local_scope; @object.num') { @object.increment }
     end
   end
+  
+  def test_array_of_expressions
+    assert_difference [ '@object.num', '@object.num + 1' ], +1 do
+      @object.increment
+    end
+  end
 end