Make String#last behave more like Array#last, i.e.

"f".last(3) => "f"  not
"f".last(3) => nil


git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3548 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activesupport/lib/active_support/core_ext/string/access.rb

@@ -50,6 +50,7 @@ module ActiveSupport #:nodoc:
         #   "hello".last(2)  # => "lo"
         #   "hello".last(10) # => "hello"
         def last(limit = 1)
+          return self if self.length < limit
           self[(-limit)..-1]
         end
       end

activesupport/test/core_ext/string_ext_test.rb

@@ -77,6 +77,12 @@ class StringInflectionsTest < Test::Unit::TestCase
 
     assert_equal "o", s.last
     assert_equal "llo", s.last(3)
+    
+    assert_equal 'x', 'x'.first
+    assert_equal 'x', 'x'.first(4)
+
+    assert_equal 'x', 'x'.last
+    assert_equal 'x', 'x'.last(4)
   end
 
   def test_starts_ends_with