4 assert("Enumerable#drop") do
7 assert_equal [4, 5, 0], a.drop(3)
8 assert_equal [], a.drop(6)
11 assert("Enumerable#drop_while") do
12 a = [1, 2, 3, 4, 5, 0]
13 assert_equal [3, 4, 5, 0], a.drop_while {|i| i < 3 }
16 assert("Enumerable#take") do
17 a = [1, 2, 3, 4, 5, 0]
18 assert_equal [1, 2, 3], a.take(3)
21 assert("Enumerable#take_while") do
22 a = [1, 2, 3, 4, 5, 0]
23 assert_equal [1, 2], a.take_while {|i| i < 3}
26 assert("Enumerable#each_cons") do
28 (1..5).each_cons(3){|e| a << e}
29 assert_equal [[1, 2, 3], [2, 3, 4], [3, 4, 5]], a
32 assert("Enumerable#each_slice") do
34 (1..10).each_slice(3){|e| a << e}
35 assert_equal [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10]], a
38 assert("Enumerable#group_by") do
39 r = (1..6).group_by {|i| i % 3 }
40 assert_equal [3, 6], r[0]
41 assert_equal [1, 4], r[1]
42 assert_equal [2, 5], r[2]
45 assert("Enumerable#sort_by") do
46 assert_equal ["car", "train", "bicycle"], %w{car bicycle train}.sort_by {|e| e.length}
49 assert("Enumerable#first") do
57 assert_equal 1, a.first
58 assert_equal [1, 2], a.first(2)
59 assert_equal [1, 2, 3], a.first(10)
67 assert("Enumerable#count") do
69 assert_equal 4, a.count
70 assert_equal 2, a.count(2)
71 assert_equal 3, a.count{|x| x % 2 == 0}
74 assert("Enumerable#flat_map") do
75 assert_equal [1, 2, 3, 4], [1, 2, 3, 4].flat_map { |e| e }
76 assert_equal [1, -1, 2, -2, 3, -3, 4, -4], [1, 2, 3, 4].flat_map { |e| [e, -e] }
77 assert_equal [1, 2, 100, 3, 4, 100], [[1, 2], [3, 4]].flat_map { |e| e + [100] }
80 assert("Enumerable#max_by") do
81 assert_equal "albatross", %w[albatross dog horse].max_by { |x| x.length }
84 assert("Enumerable#min_by") do
85 assert_equal "dog", %w[albatross dog horse].min_by { |x| x.length }
88 assert("Enumerable#minmax") do
89 a = %w(albatross dog horse)
90 assert_equal ["albatross", "horse"], a.minmax
91 assert_equal ["dog", "albatross"], a.minmax { |a, b| a.length <=> b.length }
94 assert("Enumerable#minmax_by") do
95 assert_equal ["dog", "albatross"], %w(albatross dog horse).minmax_by { |x| x.length }
98 assert("Enumerable#none?") do
99 assert_true %w(ant bear cat).none? { |word| word.length == 5 }
100 assert_false %w(ant bear cat).none? { |word| word.length >= 4 }
102 assert_true [nil, false].none?
103 assert_false [nil, true].none?
106 assert("Enumerable#one?") do
107 assert_true %w(ant bear cat).one? { |word| word.length == 4 }
108 assert_false %w(ant bear cat).one? { |word| word.length > 4 }
109 assert_false %w(ant bear cat).one? { |word| word.length < 4 }
110 assert_false [nil, true, 99].one?
111 assert_true [nil, true, false].one?
114 assert("Enumerable#each_with_object") do
115 assert_true [2, 4, 6, 8, 10, 12, 14, 16, 18, 20], (1..10).each_with_object([]) { |i, a| a << i*2 }
116 assert_raise(ArgumentError) { (1..10).each_with_object() { |i, a| a << i*2 } }