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