Fix initial value effects for sum along to ruby 2.4

Signed-off-by: Jeremy Daer <jeremydaer@gmail.com>

2 files changed, 85 insertions, 5 deletions

diff --git a/activesupport/lib/active_support/core_ext/enumerable.rb b/activesupport/lib/active_support/core_ext/enumerable.rb
index 941f20c19d..eae964bc2e 100644
--- a/activesupport/lib/active_support/core_ext/enumerable.rb
+++ b/activesupport/lib/active_support/core_ext/enumerable.rb
@@ -17,11 +17,12 @@ module Enumerable
   # The default sum of an empty list is zero. You can override this default:
   #
   #  [].sum(Payment.new(0)) { |i| i.amount } # => Payment.new(0)
-  def sum(identity = 0, &block)
+  def sum(identity = nil, &block)
     if block_given?
       map(&block).sum(identity)
     else
-      inject(:+) || identity
+      sum = identity ? inject(identity, :+) : inject(:+)
+      sum || identity || 0
     end
   end
 
@@ -91,15 +92,16 @@ end
 class Range #:nodoc:
   # Optimize range sum to use arithmetic progression if a block is not given and
   # we have a range of numeric values.
-  def sum(identity = 0)
+  def sum(identity = nil)
     if block_given? || !(first.is_a?(Integer) && last.is_a?(Integer))
       super
     else
       actual_last = exclude_end? ? (last - 1) : last
       if actual_last >= first
-        (actual_last - first + 1) * (actual_last + first) / 2
+        sum = identity || 0
+        sum + (actual_last - first + 1) * (actual_last + first) / 2
       else
-        identity
+        identity || 0
       end
     end
   end
diff --git a/activesupport/test/core_ext/enumerable_test.rb b/activesupport/test/core_ext/enumerable_test.rb
index 976c8b2b81..99c3236c35 100644
--- a/activesupport/test/core_ext/enumerable_test.rb
+++ b/activesupport/test/core_ext/enumerable_test.rb
@@ -22,6 +22,11 @@ class EnumerableTests < ActiveSupport::TestCase
     end
   end
 
+  def assert_typed_equal(e, v, cls, msg=nil)
+    assert_kind_of(cls, v, msg)
+    assert_equal(e, v, msg)
+  end
+
   def test_sums
     enum = GenericEnumerable.new([5, 15, 10])
     assert_equal 30, enum.sum
@@ -38,6 +43,40 @@ class EnumerableTests < ActiveSupport::TestCase
     payments = GenericEnumerable.new([ SummablePayment.new(5), SummablePayment.new(15) ])
     assert_equal SummablePayment.new(20), payments.sum
     assert_equal SummablePayment.new(20), payments.sum { |p| p }
+
+    sum = GenericEnumerable.new([3, 5.quo(1)]).sum
+    assert_typed_equal(8, sum, Rational)
+
+    sum = GenericEnumerable.new([3, 5.quo(1)]).sum(0.0)
+    assert_typed_equal(8.0, sum, Float)
+
+    sum = GenericEnumerable.new([3, 5.quo(1), 7.0]).sum
+    assert_typed_equal(15.0, sum, Float)
+
+    sum = GenericEnumerable.new([3, 5.quo(1), Complex(7)]).sum
+    assert_typed_equal(Complex(15), sum, Complex)
+    assert_typed_equal(15, sum.real, Rational)
+    assert_typed_equal(0, sum.imag, Integer)
+
+    sum = GenericEnumerable.new([3.5, 5]).sum
+    assert_typed_equal(8.5, sum, Float)
+
+    sum = GenericEnumerable.new([2, 8.5]).sum
+    assert_typed_equal(10.5, sum, Float)
+
+    sum = GenericEnumerable.new([1.quo(2), 1]).sum
+    assert_typed_equal(3.quo(2), sum, Rational)
+
+    sum = GenericEnumerable.new([1.quo(2), 1.quo(3)]).sum
+    assert_typed_equal(5.quo(6), sum, Rational)
+
+    sum = GenericEnumerable.new([2.0, 3.0*Complex::I]).sum
+    assert_typed_equal(Complex(2.0, 3.0), sum, Complex)
+    assert_typed_equal(2.0, sum.real, Float)
+    assert_typed_equal(3.0, sum.imag, Float)
+
+    sum = GenericEnumerable.new([1, 2]).sum(10) {|v| v * 2 }
+    assert_typed_equal(16, sum, Integer)
   end
 
   def test_nil_sums
@@ -55,6 +94,7 @@ class EnumerableTests < ActiveSupport::TestCase
     assert_equal 0, GenericEnumerable.new([]).sum
     assert_equal 0, GenericEnumerable.new([]).sum { |i| i + 10 }
     assert_equal Payment.new(0), GenericEnumerable.new([]).sum(Payment.new(0))
+    assert_typed_equal 0.0, GenericEnumerable.new([]).sum(0.0), Float
   end
 
   def test_range_sums
@@ -68,6 +108,10 @@ class EnumerableTests < ActiveSupport::TestCase
     assert_equal 5, (10..0).sum(5)
     assert_equal 10, (10..10).sum
     assert_equal 42, (10...10).sum(42)
+    assert_typed_equal 20.0, (1..4).sum(0.0) { |i| i * 2 }, Float
+    assert_typed_equal 10.0, (1..4).sum(0.0), Float
+    assert_typed_equal 20.0, (1..4).sum(10.0), Float
+    assert_typed_equal 5.0, (10..0).sum(5.0), Float
   end
 
   def test_array_sums
@@ -86,6 +130,40 @@ class EnumerableTests < ActiveSupport::TestCase
     payments = [ SummablePayment.new(5), SummablePayment.new(15) ]
     assert_equal SummablePayment.new(20), payments.sum
     assert_equal SummablePayment.new(20), payments.sum { |p| p }
+
+    sum = [3, 5.quo(1)].sum
+    assert_typed_equal(8, sum, Rational)
+
+    sum = [3, 5.quo(1)].sum(0.0)
+    assert_typed_equal(8.0, sum, Float)
+
+    sum = [3, 5.quo(1), 7.0].sum
+    assert_typed_equal(15.0, sum, Float)
+
+    sum = [3, 5.quo(1), Complex(7)].sum
+    assert_typed_equal(Complex(15), sum, Complex)
+    assert_typed_equal(15, sum.real, Rational)
+    assert_typed_equal(0, sum.imag, Integer)
+
+    sum = [3.5, 5].sum
+    assert_typed_equal(8.5, sum, Float)
+
+    sum = [2, 8.5].sum
+    assert_typed_equal(10.5, sum, Float)
+
+    sum = [1.quo(2), 1].sum
+    assert_typed_equal(3.quo(2), sum, Rational)
+
+    sum = [1.quo(2), 1.quo(3)].sum
+    assert_typed_equal(5.quo(6), sum, Rational)
+
+    sum = [2.0, 3.0*Complex::I].sum
+    assert_typed_equal(Complex(2.0, 3.0), sum, Complex)
+    assert_typed_equal(2.0, sum.real, Float)
+    assert_typed_equal(3.0, sum.imag, Float)
+
+    sum = [1, 2].sum(10) {|v| v * 2 }
+    assert_typed_equal(16, sum, Integer)
   end
 
   def test_index_by