require 'matrix'

ruby_version_is "1.9.3" do
  describe "Matrix#permutation?" do
    it "returns true for a permutation Matrix" do
      Matrix[[0, 1, 0], [0, 0, 1], [1, 0, 0]].permutation?.should be_true
    end

    it "returns false for a non permutation square Matrix" do
      Matrix[[0, 1], [0, 0]].permutation?.should be_false
      Matrix[[-1, 0], [0, -1]].permutation?.should be_false
      Matrix[[1, 0], [1, 0]].permutation?.should be_false
      Matrix[[1, 0], [1, 1]].permutation?.should be_false
    end

    it "returns true for an empty 0x0 matrix" do
      Matrix.empty(0,0).permutation?.should be_true
    end

    it "raises an error for rectangular matrices" do
      [
        Matrix[[0], [0]],
        Matrix[[0, 0]],
        Matrix.empty(0, 2),
        Matrix.empty(2, 0),
      ].each do |rectangual_matrix|
        lambda {
          rectangual_matrix.permutation?
        }.should raise_error(Matrix::ErrDimensionMismatch)
      end
    end
  end
end
