spec/ruby/library/matrix/column_spec.rb


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require_relative '../../spec_helper'

ruby_version_is ""..."3.1" do
  require 'matrix'

  describe "Matrix#column" do
    before :all do
      @m =  Matrix[[1,2,3], [2,3,4]]
    end

    it "returns a Vector when called without a block" do
      @m.column(1).should == Vector[2,3]
    end

    it "yields each element in the column to the block" do
      a = []
      @m.column(1) {|n| a << n }
      a.should == [2,3]
    end

    it "counts backwards for negative argument" do
      @m.column(-1).should == Vector[3, 4]
    end

    it "returns self when called with a block" do
      @m.column(0) { |x| x }.should equal(@m)
    end

    it "returns nil when out of bounds" do
      @m.column(3).should == nil
    end

    it "never yields when out of bounds" do
      -> { @m.column(3){ raise } }.should_not raise_error
      -> { @m.column(-4){ raise } }.should_not raise_error
    end
  end
end