Add extra tests to ensure Hash#slice works with an array as a key. #613

Signed-off-by: Pratik Naik <pratiknaik@gmail.com>

2 files changed, 26 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/core_ext/hash/slice.rb b/activesupport/lib/active_support/core_ext/hash/slice.rb
index be4dec6e53..3f14470f36 100644
--- a/activesupport/lib/active_support/core_ext/hash/slice.rb
+++ b/activesupport/lib/active_support/core_ext/hash/slice.rb
@@ -9,6 +9,11 @@ module ActiveSupport #:nodoc:
       #   end
       #
       #   search(options.slice(:mass, :velocity, :time))
+      #
+      # If you have an array of keys you want to limit to, you should splat them:
+      #
+      #   valid_keys = [:mass, :velocity, :time]
+      #   search(options.slice(*valid_keys))
       module Slice
         # Returns a new hash with only the given keys.
         def slice(*keys)
diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb
index 2ab7681a8a..fc8ed45358 100644
--- a/activesupport/test/core_ext/hash_ext_test.rb
+++ b/activesupport/test/core_ext/hash_ext_test.rb
@@ -292,6 +292,27 @@ class HashExtTest < Test::Unit::TestCase
     assert_equal expected, original
   end
 
+  def test_slice_with_an_array_key
+    original = { :a => 'x', :b => 'y', :c => 10, [:a, :b] => "an array key" }
+    expected = { [:a, :b] => "an array key", :c => 10 }
+
+    # Should return a new hash with only the given keys when given an array key.
+    assert_equal expected, original.slice([:a, :b], :c)
+    assert_not_equal expected, original
+
+    # Should replace the hash with only the given keys when given an array key.
+    assert_equal expected, original.slice!([:a, :b], :c)
+    assert_equal expected, original
+  end
+
+  def test_slice_with_splatted_keys
+    original = { :a => 'x', :b => 'y', :c => 10, [:a, :b] => "an array key" }
+    expected = { :a => 'x', :b => "y" }
+
+    # Should grab each of the splatted keys.
+    assert_equal expected, original.slice(*[:a, :b])
+  end
+
   def test_indifferent_slice
     original = { :a => 'x', :b => 'y', :c => 10 }.with_indifferent_access
     expected = { :a => 'x', :b => 'y' }.with_indifferent_access