require File.expand_path('../../../spec_helper', __FILE__)
require File.expand_path('../fixtures/classes', __FILE__)
require 'matrix'

ruby_version_is "1.8.8" do
  describe "Matrix#empty?" do
    it "returns true when the Matrix is empty" do
      Matrix[ ].empty?.should be_true
      Matrix[ [], [], [] ].empty?.should be_true
      Matrix[ [], [], [] ].transpose.empty?.should be_true
    end

    it "returns false when the Matrix has elements" do
      Matrix[ [1, 2] ].empty?.should be_false
      Matrix[ [1], [2] ].empty?.should be_false
    end

    it "doesn't accept any parameter" do
      lambda{
        Matrix[ [1, 2] ].empty?(42)
      }.should raise_error(ArgumentError)
    end
  end

  describe "Matrix.empty" do
    it "returns an empty matrix of the requested size" do
      m = Matrix.empty(3, 0)
      m.row_size.should == 3
      m.column_size.should == 0

      m = Matrix.empty(0, 3)
      m.row_size.should == 0
      m.column_size.should == 3
    end

    it "has arguments defaulting to 0" do
      Matrix.empty.should == Matrix.empty(0, 0)
      Matrix.empty(42).should == Matrix.empty(42, 0)
    end

    it "does not accept more than two parameters" do
      lambda{
        Matrix.empty(1, 2, 3)
      }.should raise_error(ArgumentError)
    end

    it "raises an error if both dimensions are > 0" do
      lambda{
        Matrix.empty(1, 2)
      }.should raise_error(ArgumentError)
    end

    it "raises an error if any dimension is < 0" do
      lambda{
        Matrix.empty(-2, 0)
      }.should raise_error(ArgumentError)

      lambda{
        Matrix.empty(0, -2)
      }.should raise_error(ArgumentError)
    end

  end

  describe "for a subclass of Matrix" do
    it "returns an instance of that subclass" do
      MatrixSub.empty(0, 1).should be_an_instance_of(MatrixSub)
    end
  end
end
