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require_relative '../../spec_helper'
require_relative 'fixtures/classes'
describe "Array#sample" do
it "samples evenly" do
ary = [0, 1, 2, 3]
3.times do |i|
counts = [0, 0, 0, 0]
4000.times do
counts[ary.sample(3)[i]] += 1
end
counts.each do |count|
(800..1200).should include(count)
end
end
end
it "returns nil for an empty Array" do
[].sample.should be_nil
end
it "returns a single value when not passed a count" do
[4].sample.should equal(4)
end
it "returns an empty Array when passed zero" do
[4].sample(0).should == []
end
it "returns an Array of elements when passed a count" do
[1, 2, 3, 4].sample(3).should be_an_instance_of(Array)
end
it "returns elements from the Array" do
array = [1, 2, 3, 4]
array.sample(3).all? { |x| array.should include(x) }
end
it "returns at most the number of elements in the Array" do
array = [1, 2, 3, 4]
result = array.sample(20)
result.size.should == 4
end
it "does not return the same value if the Array has unique values" do
array = [1, 2, 3, 4]
result = array.sample(20)
result.sort.should == array
end
it "may return the same value if the array is not unique" do
[4, 4].sample(2).should == [4,4]
end
it "calls #to_int to convert the count when passed an Object" do
[1, 2, 3, 4].sample(mock_int(2)).size.should == 2
end
it "raises ArgumentError when passed a negative count" do
-> { [1, 2].sample(-1) }.should raise_error(ArgumentError)
end
it "does not return subclass instances with Array subclass" do
ArraySpecs::MyArray[1, 2, 3].sample(2).should be_an_instance_of(Array)
end
describe "with options" do
it "calls #rand on the Object passed by the :random key in the arguments Hash" do
obj = mock("array_sample_random")
obj.should_receive(:rand).and_return(0.5)
[1, 2].sample(random: obj).should be_an_instance_of(Fixnum)
end
it "raises a NoMethodError if an object passed for the RNG does not define #rand" do
obj = BasicObject.new
-> { [1, 2].sample(random: obj) }.should raise_error(NoMethodError)
end
describe "when the object returned by #rand is a Fixnum" do
it "uses the fixnum as index" do
random = mock("array_sample_random_ret")
random.should_receive(:rand).and_return(0)
[1, 2].sample(random: random).should == 1
random = mock("array_sample_random_ret")
random.should_receive(:rand).and_return(1)
[1, 2].sample(random: random).should == 2
end
it "raises a RangeError if the value is less than zero" do
random = mock("array_sample_random")
random.should_receive(:rand).and_return(-1)
-> { [1, 2].sample(random: random) }.should raise_error(RangeError)
end
it "raises a RangeError if the value is equal to the Array size" do
random = mock("array_sample_random")
random.should_receive(:rand).and_return(2)
-> { [1, 2].sample(random: random) }.should raise_error(RangeError)
end
end
end
describe "when the object returned by #rand is not a Fixnum but responds to #to_int" do
it "calls #to_int on the Object" do
value = mock("array_sample_random_value")
value.should_receive(:to_int).and_return(1)
random = mock("array_sample_random")
random.should_receive(:rand).and_return(value)
[1, 2].sample(random: random).should == 2
end
it "raises a RangeError if the value is less than zero" do
value = mock("array_sample_random_value")
value.should_receive(:to_int).and_return(-1)
random = mock("array_sample_random")
random.should_receive(:rand).and_return(value)
-> { [1, 2].sample(random: random) }.should raise_error(RangeError)
end
it "raises a RangeError if the value is equal to the Array size" do
value = mock("array_sample_random_value")
value.should_receive(:to_int).and_return(2)
random = mock("array_sample_random")
random.should_receive(:rand).and_return(value)
-> { [1, 2].sample(random: random) }.should raise_error(RangeError)
end
end
end
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