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require File.expand_path('../../../spec_helper', __FILE__)
require 'prime'
describe :prime_each, shared: true do
before :each do
ScratchPad.record []
end
it "enumerates primes" do
primes = Prime.instance
result = []
primes.each { |p|
result << p
break if p > 10
}
result.should == [2, 3, 5, 7, 11]
end
it "yields ascending primes to the block" do
previous = 1
@object.each do |prime|
break if prime > 1000
ScratchPad << prime
prime.should > previous
previous = prime
end
all_prime = true
ScratchPad.recorded.all? do |prime|
all_prime &&= (2..Math.sqrt(prime)).all? { |d| prime % d != 0 }
end
all_prime.should be_true
end
it "returns the last evaluated expression in the passed block" do
@object.each { break :value }.should equal(:value)
end
describe "when not passed a block" do
before :each do
@prime_enum = @object.each
end
it "returns an object that is Enumerable" do
@prime_enum.each.should be_kind_of(Enumerable)
end
it "returns an object that responds to #with_index" do
@prime_enum.should respond_to(:with_index)
end
it "returns an object that responds to #with_object" do
@prime_enum.should respond_to(:with_object)
end
it "returns an object that responds to #next" do
@prime_enum.should respond_to(:next)
end
it "returns an object that responds to #rewind" do
@prime_enum.should respond_to(:rewind)
end
it "yields primes starting at 2 independent of prior enumerators" do
@prime_enum.next.should == 2
@prime_enum.next.should == 3
@object.each { |prime| break prime }.should == 2
end
it "returns an enumerator that yields previous primes when #rewind is called" do
@prime_enum.next.should == 2
@prime_enum.next.should == 3
@prime_enum.rewind
@prime_enum.next.should == 2
end
it "returns independent enumerators" do
enum = @object.each
enum.next.should == 2
enum.next.should == 3
@prime_enum.next.should == 2
enum.next.should == 5
end
end
end
describe :prime_each_with_arguments, shared: true do
before :each do
ScratchPad.record []
end
it "yields ascending primes less than or equal to the argument" do
bound = 1000
previous = 1
@object.each(bound) do |prime|
ScratchPad << prime
prime.should > previous
previous = prime
end
ScratchPad.recorded.all? do |prime|
(2..Math.sqrt(prime)).all? { |d| prime % d != 0 }
end.should be_true
ScratchPad.recorded.all? { |prime| prime <= bound }.should be_true
end
it "returns nil when no prime is generated" do
@object.each(1) { :value }.should be_nil
end
it "yields primes starting at 2 independent of prior enumeration" do
@object.each(10) { |prime| prime }.should == 7
@object.each(10) { |prime| break prime }.should == 2
end
it "accepts a pseudo-prime generator as the second argument" do
generator = mock('very bad pseudo-prime generator')
generator.should_receive(:upper_bound=).with(100)
generator.should_receive(:each).and_yield(2).and_yield(3).and_yield(4)
@object.each(100, generator) { |prime| ScratchPad << prime }
ScratchPad.recorded.should == [2, 3, 4]
end
describe "when not passed a block" do
it "returns an object that returns primes less than or equal to the bound" do
bound = 100
@object.each(bound).all? { |prime| prime <= bound }.should be_true
end
end
end
describe "Prime.each" do
it_behaves_like :prime_each, :each, Prime
end
describe "Prime.each" do
it_behaves_like :prime_each_with_arguments, :each, Prime
end
describe "Prime#each with Prime.instance" do
it_behaves_like :prime_each, :each, Prime.instance
end
describe "Prime#each with Prime.instance" do
it_behaves_like :prime_each_with_arguments, :each, Prime.instance
end
describe "Prime#each with Prime.instance" do
before :each do
@object = Prime.instance
end
it_behaves_like :prime_each, :each
it "resets the enumerator with each call" do
@object.each { |prime| break if prime > 10 }
@object.each { |prime| break prime }.should == 2
end
end
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