add test cases for negative position in Array#from

rails · May 23, 2014 · 3920d64 · 3920d64
1 parent 0cc7f02
commit 3920d64
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diff --git a/activesupport/lib/active_support/core_ext/array/access.rb b/activesupport/lib/active_support/core_ext/array/access.rb
@@ -5,6 +5,8 @@ class Array
   #   %w( a b c d ).from(2)  # => ["c", "d"]
   #   %w( a b c d ).from(10) # => []
   #   %w().from(0)           # => []
+  #   %w( a b c d ).from(-2) # => ["c", "d"]
+  #   %w( a b c ).from(-10)  # => []
   def from(position)
     self[position, length] || []
   end

diff --git a/activesupport/test/core_ext/array_ext_test.rb b/activesupport/test/core_ext/array_ext_test.rb
@@ -10,6 +10,8 @@ def test_from
     assert_equal %w( a b c d ), %w( a b c d ).from(0)
     assert_equal %w( c d ), %w( a b c d ).from(2)
     assert_equal %w(), %w( a b c d ).from(10)
+    assert_equal %w( d e ), %w( a b c d e ).from(-2)
+    assert_equal %w(), %w( a b c d e ).from(-10)
   end
 
   def test_to