summaryrefslogtreecommitdiff
path: root/test/test_prime.rb
blob: 7ff07eeb6a5e784078fb6e0f54d4a6069160056e (plain)
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
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
# frozen_string_literal: false
require 'test/unit'
require 'prime'
require 'timeout'

class TestPrime < Test::Unit::TestCase
  # The first 100 prime numbers
  PRIMES = [
    2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37,
    41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83,
    89, 97, 101, 103, 107, 109, 113, 127, 131,
    137, 139, 149, 151, 157, 163, 167, 173, 179,
    181, 191, 193, 197, 199, 211, 223, 227, 229,
    233, 239, 241, 251, 257, 263, 269, 271, 277,
    281, 283, 293, 307, 311, 313, 317, 331, 337,
    347, 349, 353, 359, 367, 373, 379, 383, 389,
    397, 401, 409, 419, 421, 431, 433, 439, 443,
    449, 457, 461, 463, 467, 479, 487, 491, 499,
    503, 509, 521, 523, 541,
  ]
  def test_each
    primes = []
    Prime.each do |p|
      break if p > 541
      primes << p
    end
    assert_equal PRIMES, primes
  end

  def test_each_by_prime_number_theorem
    3.upto(15) do |i|
      max = 2**i
      primes = []
      Prime.each do |p|
        break if p >= max
        primes << p
      end

      # Prime number theorem
      assert_operator primes.length, :>=, max/Math.log(max)
      delta = 0.05
      li = (2..max).step(delta).inject(0){|sum,x| sum + delta/Math.log(x)}
      assert_operator primes.length, :<=, li
    end
  end

  def test_each_without_block
    enum = Prime.each
    assert_respond_to(enum, :each)
    assert_kind_of(Enumerable, enum)
    assert_respond_to(enum, :with_index)
    assert_respond_to(enum, :next)
    assert_respond_to(enum, :succ)
    assert_respond_to(enum, :rewind)
  end

  def test_instance_without_block
    enum = Prime.instance.each
    assert_respond_to(enum, :each)
    assert_kind_of(Enumerable, enum)
    assert_respond_to(enum, :with_index)
    assert_respond_to(enum, :next)
    assert_respond_to(enum, :succ)
    assert_respond_to(enum, :rewind)
  end

  def test_new
    exception = assert_raise(NoMethodError) { Prime.new }
  end

  def test_enumerator_succ
    enum = Prime.each
    assert_equal PRIMES[0, 50], 50.times.map{ enum.succ }
    assert_equal PRIMES[50, 50], 50.times.map{ enum.succ }
    enum.rewind
    assert_equal PRIMES[0, 100], 100.times.map{ enum.succ }
  end

  def test_enumerator_with_index
    enum = Prime.each
    last = -1
    enum.with_index do |p,i|
      break if i >= 100
      assert_equal last+1, i
      assert_equal PRIMES[i], p
      last = i
    end
  end

  def test_enumerator_with_index_with_offset
    enum = Prime.each
    last = 5-1
    enum.with_index(5).each do |p,i|
      break if i >= 100+5
      assert_equal last+1, i
      assert_equal PRIMES[i-5], p
      last = i
    end
  end

  def test_enumerator_with_object
    object = Object.new
    enum = Prime.each
    enum.with_object(object).each do |p, o|
      assert_equal object, o
      break
    end
  end

  def test_enumerator_size
    enum = Prime.each
    assert_equal Float::INFINITY, enum.size
    assert_equal Float::INFINITY, enum.with_object(nil).size
    assert_equal Float::INFINITY, enum.with_index(42).size
  end

  def test_default_instance_does_not_have_compatibility_methods
    assert_not_respond_to(Prime.instance, :succ)
    assert_not_respond_to(Prime.instance, :next)
  end

  def test_prime_each_basic_argument_checking
    assert_raise(ArgumentError) { Prime.prime?(1,2) }
    assert_raise(ArgumentError) { Prime.prime?(1.2) }
  end

  class TestInteger < Test::Unit::TestCase
    def test_prime_division
      pd = PRIMES.inject(&:*).prime_division
      assert_equal PRIMES.map{|p| [p, 1]}, pd

      pd = (-PRIMES.inject(&:*)).prime_division
      assert_equal [-1, *PRIMES].map{|p| [p, 1]}, pd
    end

    def test_from_prime_division
      assert_equal PRIMES.inject(&:*), Integer.from_prime_division(PRIMES.map{|p| [p,1]})

      assert_equal(-PRIMES.inject(&:*), Integer.from_prime_division([[-1, 1]] + PRIMES.map{|p| [p,1]}))
    end

    def test_prime?
      PRIMES.each do |p|
        assert_predicate(p, :prime?)
      end

      composites = (0..PRIMES.last).to_a - PRIMES
      composites.each do |c|
        assert_not_predicate(c, :prime?)
      end

      # mersenne numbers
      assert_predicate((2**31-1), :prime?)
      assert_not_predicate((2**32-1), :prime?)

      # fermat numbers
      assert_predicate((2**(2**4)+1), :prime?)
      assert_not_predicate((2**(2**5)+1), :prime?) # Euler!

      # large composite
      assert_not_predicate(((2**13-1) * (2**17-1)), :prime?)

      # factorial
      assert_not_predicate((2...100).inject(&:*), :prime?)

      # negative
      assert_not_predicate(-1, :prime?)
      assert_not_predicate(-2, :prime?)
      assert_not_predicate(-3, :prime?)
      assert_not_predicate(-4, :prime?)
    end
  end

  def test_eratosthenes_works_fine_after_timeout
    sieve = Prime::EratosthenesSieve.instance
    sieve.send(:initialize)
    # simulates that Timeout.timeout interrupts Prime::EratosthenesSieve#compute_primes
    class << Integer
      alias_method :org_sqrt, :sqrt
    end
    begin
      def Integer.sqrt(n)
        sleep 10 if /compute_primes/ =~ caller.first
        org_sqrt(n)
      end
      assert_raise(Timeout::Error) do
        Timeout.timeout(0.5) { Prime.each(7*37){} }
      end
    ensure
      class << Integer
        alias_method :sqrt, :org_sqrt
        remove_method :org_sqrt
      end
    end

    assert_not_include Prime.each(7*37).to_a, 7*37, "[ruby-dev:39465]"
  end
end