spec/ruby/library/matrix/minus_spec.rb


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require_relative '../../spec_helper'

ruby_version_is ""..."3.1" do
  require_relative 'fixtures/classes'
  require 'matrix'

  describe "Matrix#-" do
    before :each do
      @a = Matrix[ [1, 2], [3, 4] ]
      @b = Matrix[ [4, 5], [6, 7] ]
    end

    it "returns the result of subtracting the corresponding elements of other from self" do
      (@a - @b).should == Matrix[ [-3,-3], [-3,-3] ]
    end

    it "returns an instance of Matrix" do
      (@a - @b).should be_kind_of(Matrix)
    end

    it "raises a Matrix::ErrDimensionMismatch if the matrices are different sizes" do
      -> { @a - Matrix[ [1] ] }.should raise_error(Matrix::ErrDimensionMismatch)
    end

    it "raises a ExceptionForMatrix::ErrOperationNotDefined if other is a Numeric Type" do
      -> { @a - 2            }.should raise_error(Matrix::ErrOperationNotDefined)
      -> { @a - 1.2          }.should raise_error(Matrix::ErrOperationNotDefined)
      -> { @a - bignum_value }.should raise_error(Matrix::ErrOperationNotDefined)
    end

    it "raises a TypeError if other is of wrong type" do
      -> { @a - nil        }.should raise_error(TypeError)
      -> { @a - "a"        }.should raise_error(TypeError)
      -> { @a - [ [1, 2] ] }.should raise_error(TypeError)
      -> { @a - Object.new }.should raise_error(TypeError)
    end

    describe "for a subclass of Matrix" do
      it "returns an instance of that subclass" do
        m = MatrixSub.ins
        (m-m).should be_an_instance_of(MatrixSub)
      end
    end
  end
end