ruby--ruby/spec/ruby/core/array/dig_spec.rb

require File.expand_path('../../../spec_helper', __FILE__)

ruby_version_is '2.3' do
  describe "Array#dig" do

    it "returns #at with one arg" do
      ['a'].dig(0).should == 'a'
      ['a'].dig(1).should be_nil
    end

    it "recurses array elements" do
      a = [ [ 1, [2, '3'] ] ]
      a.dig(0, 0).should == 1
      a.dig(0, 1, 1).should == '3'
      a.dig(0, -1, 0).should == 2
    end

    it "returns the nested value specified if the sequence includes a key" do
      a = [42, { foo: :bar }]
      a.dig(1, :foo).should == :bar
    end

    it "raises a TypeError for a non-numeric index" do
      lambda {
        ['a'].dig(:first)
      }.should raise_error(TypeError)
    end

    it "raises a TypeError if any intermediate step does not respond to #dig" do
      a = [1, 2]
      lambda {
        a.dig(0, 1)
      }.should raise_error(TypeError)
    end

    it "raises an ArgumentError if no arguments provided" do
      lambda {
        [10].dig()
      }.should raise_error(ArgumentError)
    end

    it "returns nil if any intermediate step is nil" do
      a = [[1, [2, 3]]]
      a.dig(1, 2, 3).should == nil
    end

    it "calls #dig on the result of #at with the remaining arguments" do
      h = [[nil, [nil, nil, 42]]]
      h[0].should_receive(:dig).with(1, 2).and_return(42)
      h.dig(0, 1, 2).should == 42
    end

  end
end