require_relative "../../spec_helper"

describe "Rational#truncate" do
  before do
    @rational = Rational(2200, 7)
  end

  describe "with no arguments (precision = 0)" do
    it "returns an integer" do
      @rational.truncate.should be_kind_of(Integer)
    end

    it "returns the truncated value toward 0" do
      @rational.truncate.should == 314
      Rational(1, 2).truncate.should == 0
      Rational(-1, 2).truncate.should == 0
    end
  end

  describe "with an explicit precision = 0" do
    it "returns an integer" do
      @rational.truncate(0).should be_kind_of(Integer)
    end

    it "returns the truncated value toward 0" do
      @rational.truncate(0).should == 314
      Rational(1, 2).truncate(0).should == 0
      Rational(-1, 2).truncate(0).should == 0
    end
  end

  describe "with a precision < 0" do
    it "returns an integer" do
      @rational.truncate(-2).should be_kind_of(Integer)
      @rational.truncate(-1).should be_kind_of(Integer)
    end

    it "moves the truncation point n decimal places left" do
      @rational.truncate(-3).should == 0
      @rational.truncate(-2).should == 300
      @rational.truncate(-1).should == 310
    end
  end

  describe "with a precision > 0" do
    it "returns a Rational" do
      @rational.truncate(1).should be_kind_of(Rational)
      @rational.truncate(2).should be_kind_of(Rational)
    end

    it "moves the truncation point n decimal places right" do
      @rational.truncate(1).should == Rational(1571, 5)
      @rational.truncate(2).should == Rational(7857, 25)
      @rational.truncate(3).should == Rational(62857, 200)
    end
  end

  describe "with an invalid value for precision" do
    it "raises a TypeError" do
      -> { @rational.truncate(nil) }.should raise_error(TypeError, "not an integer")
      -> { @rational.truncate(1.0) }.should raise_error(TypeError, "not an integer")
      -> { @rational.truncate('') }.should raise_error(TypeError, "not an integer")
    end

    it "does not call to_int on the argument" do
      object = Object.new
      object.should_not_receive(:to_int)
      -> { @rational.truncate(object) }.should raise_error(TypeError, "not an integer")
    end
  end
end
