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

ruby_version_is "1.9" do
  describe "Random.srand" do

    it "returns an arbitrary seed if .srand wasn't called previously with an argument and no argument is supplied this time" do
      Random.srand # Reset to random seed in case .srand was called previously
      Random.srand.should_not == Random.srand
    end

    it "returns the previous argument to .srand if one was given and no argument is supplied" do
      Random.srand 34
      Random.srand.should == 34
    end

    it "returns an arbitrary seed if .srand wasn't called previously with an argument and 0 is supplied this time" do
      Random.srand # Reset to random seed in case .srand was called previously
      Random.srand(0).should_not == Random.srand(0)
    end

    it "returns the previous argument to .srand if one was given and 0 is supplied" do
      Random.srand 34
      Random.srand(0).should == 34
    end

    it "seeds Random.rand such that its return value is deterministic" do
      Random.srand 176542
      a = 20.times.map { Random.rand }
      Random.srand 176542
      b = 20.times.map { Random.rand }
      a.should == b
    end

    it "seeds Kernel.rand such that its return value is deterministic" do
      Random.srand 176542
      a = 20.times.map { Kernel.rand }
      Random.srand 176542
      b = 20.times.map { Kernel.rand }
      a.should == b
    end

  end
end
