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

describe "Matrix.zero" do
  it "returns an object of type Matrix" do
    Matrix.zero(3).should be_kind_of(Matrix)
  end

  it "creates a n x n matrix" do
    m3 = Matrix.zero(3)
    m3.row_size.should == 3
    m3.column_size.should == 3

    m8 = Matrix.zero(8)
    m8.row_size.should == 8
    m8.column_size.should == 8
  end

  it "initializes all cells to 0" do
    size = 10
    m = Matrix.zero(size)

    (0...size).each do |i|
      (0...size).each do |j|
        m[i, j].should == 0
      end
    end
  end

  describe "for a subclass of Matrix" do
    it "returns an instance of that subclass" do
      MatrixSub.zero(3).should be_an_instance_of(MatrixSub)
    end
  end
end

describe "Matrix.zero?" do
  it "returns true for empty matrices" do
    Matrix.empty.zero?.should == true
    Matrix.empty(3,0).zero?.should == true
    Matrix.empty(0,3).zero?.should == true
  end

  it "returns true for matrices with zero entries" do
    Matrix.zero(2,3).zero?.should == true
  end

  it "returns false for matrices with non zero entries" do
    Matrix[[1]].zero?.should == false
  end
end