Add ActiveSupport::ArrayInquirer and Array#inquiry

Wrapping an array in an `ArrayInquirer` gives a friendlier way to check its
string-like contents. For example, `request.variant` returns an `ArrayInquirer`
object. To check a request's variants, you can call:

    request.variant.phone?
    request.variant.any?(:phone, :tablet)

...instead of:

    request.variant.include?(:phone)
    request.variant.any? { |v| v.in?([:phone, :tablet]) }

`Array#inquiry` is a shortcut for wrapping the receiving array in an
`ArrayInquirer`:

    pets = [:cat, :dog]
    pets.cat?    # => true
    pets.ferret? # => false
    pets.any?(:cat, :ferret} # => true

1 files changed, 35 insertions, 0 deletions

diff --git a/activesupport/test/array_inquirer_test.rb b/activesupport/test/array_inquirer_test.rb
new file mode 100644
index 0000000000..488e0d34a9
--- /dev/null
+++ b/activesupport/test/array_inquirer_test.rb
@@ -0,0 +1,35 @@
+require 'abstract_unit'
+
+class ArrayInquirerTest < ActiveSupport::TestCase
+  def setup
+    @array_inquirer = ActiveSupport::ArrayInquirer.new([:mobile, :tablet])
+  end
+
+  def test_individual
+    assert @array_inquirer.mobile?
+    assert @array_inquirer.tablet?
+    assert_not @array_inquirer.desktop?
+  end
+
+  def test_any
+    assert @array_inquirer.any?(:mobile, :desktop)
+    assert @array_inquirer.any?(:watch, :tablet)
+    assert_not @array_inquirer.any?(:desktop, :watch)
+  end
+
+  def test_any_with_block
+    assert @array_inquirer.any? { |v| v == :mobile }
+    assert_not @array_inquirer.any? { |v| v == :desktop }
+  end
+
+  def test_respond_to
+    assert_respond_to @array_inquirer, :development?
+  end
+
+  def test_inquiry
+    result = [:mobile, :tablet].inquiry
+
+    assert_instance_of ActiveSupport::ArrayInquirer, result
+    assert_equal @array_inquirer, result
+  end
+end