spec/ruby/core/integer/even_spec.rb


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require File.expand_path('../../../spec_helper', __FILE__)

describe "Integer#even?" do
  context "fixnum" do
    it "returns true for a Fixnum when it is an even number" do
      (-2).even?.should be_true
      (-1).even?.should be_false

      0.even?.should be_true
      1.even?.should be_false
      2.even?.should be_true
    end

    it "returns true for a Bignum when it is an even number" do
      bignum_value(0).even?.should be_true
      bignum_value(1).even?.should be_false

      (-bignum_value(0)).even?.should be_true
      (-bignum_value(1)).even?.should be_false
    end
  end

  context "bignum" do
    it "returns true if self is even and positive" do
      (10000**10).even?.should be_true
    end

    it "returns true if self is even and negative" do
      (-10000**10).even?.should be_true
    end

    it "returns false if self is odd and positive" do
      (9879**976).even?.should be_false
    end

    it "returns false if self is odd and negative" do
      (-9879**976).even?.should be_false
    end
  end
end