Update to ruby/spec@254c380

1 files changed, 29 insertions, 0 deletions

diff --git a/spec/ruby/core/array/sum_spec.rb b/spec/ruby/core/array/sum_spec.rb
index 39c769d328..8ca8353a67 100644
--- a/spec/ruby/core/array/sum_spec.rb
+++ b/spec/ruby/core/array/sum_spec.rb
@@ -9,6 +9,35 @@ describe "Array#sum" do
     [1, 2, 3].sum { |i| i * 10 }.should == 60
   end
 
+  # https://bugs.ruby-lang.org/issues/12217
+  # https://github.com/ruby/ruby/blob/master/doc/ChangeLog-2.4.0#L6208-L6214
+  it "uses Kahan's compensated summation algorithm for precise sum of float numbers" do
+    floats = [2.7800000000000002, 5.0, 2.5, 4.44, 3.89, 3.89, 4.44, 7.78, 5.0, 2.7800000000000002, 5.0, 2.5]
+    naive_sum = floats.reduce { |sum, e| sum + e }
+    naive_sum.should == 50.00000000000001
+    floats.sum.should == 50.0
+  end
+
+  it "handles infinite values and NaN" do
+    [1.0, Float::INFINITY].sum.should == Float::INFINITY
+    [1.0, -Float::INFINITY].sum.should == -Float::INFINITY
+    [1.0, Float::NAN].sum.should.nan?
+
+    [Float::INFINITY, 1.0].sum.should == Float::INFINITY
+    [-Float::INFINITY, 1.0].sum.should == -Float::INFINITY
+    [Float::NAN, 1.0].sum.should.nan?
+
+    [Float::NAN, Float::INFINITY].sum.should.nan?
+    [Float::INFINITY, Float::NAN].sum.should.nan?
+
+    [Float::INFINITY, -Float::INFINITY].sum.should.nan?
+    [-Float::INFINITY, Float::INFINITY].sum.should.nan?
+
+    [Float::INFINITY, Float::INFINITY].sum.should == Float::INFINITY
+    [-Float::INFINITY, -Float::INFINITY].sum.should == -Float::INFINITY
+    [Float::NAN, Float::NAN].sum.should.nan?
+  end
+
   it "returns init value if array is empty" do
     [].sum(-1).should == -1
   end