1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
require_relative '../../spec_helper'
describe "Array#sum" do
it "returns the sum of elements" do
[1, 2, 3].sum.should == 6
end
it "applies a block to each element before adding if it's given" 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
it "returns 0 if array is empty and init is omitted" do
[].sum.should == 0
end
it "adds init value to the sum of elements" do
[1, 2, 3].sum(10).should == 16
end
it "can be used for non-numeric objects by providing init value" do
["a", "b", "c"].sum("").should == "abc"
end
it 'raises TypeError if any element are not numeric' do
-> { ["a"].sum }.should raise_error(TypeError)
end
it 'raises TypeError if any element cannot be added to init value' do
-> { [1].sum([]) }.should raise_error(TypeError)
end
it "calls + to sum the elements" do
a = mock("a")
b = mock("b")
a.should_receive(:+).with(b).and_return(42)
[b].sum(a).should == 42
end
end
|
