spec/ruby/core/thread/fetch_spec.rb


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require_relative '../../spec_helper'

describe 'Thread#fetch' do
  describe 'with 2 arguments' do
    it 'returns the value of the fiber-local variable if value has been assigned' do
      th = Thread.new { Thread.current[:cat] = 'meow' }
      th.join
      th.fetch(:cat, true).should == 'meow'
    end

    it "returns the default value if fiber-local variable hasn't been assigned" do
      th = Thread.new {}
      th.join
      th.fetch(:cat, true).should == true
    end
  end

  describe 'with 1 argument' do
    it 'raises a KeyError when the Thread does not have a fiber-local variable of the same name' do
      th = Thread.new {}
      th.join
      -> { th.fetch(:cat) }.should raise_error(KeyError)
    end

    it 'returns the value of the fiber-local variable if value has been assigned' do
      th = Thread.new { Thread.current[:cat] = 'meow' }
      th.join
      th.fetch(:cat).should == 'meow'
    end
  end

  describe 'with a block' do
    it 'returns the value of the fiber-local variable if value has been assigned' do
      th = Thread.new { Thread.current[:cat] = 'meow' }
      th.join
      th.fetch(:cat) { true }.should == 'meow'
    end

    it "returns the block value if fiber-local variable hasn't been assigned" do
      th = Thread.new {}
      th.join
      th.fetch(:cat) { true }.should == true
    end

    it "does not call the block if value has been assigned" do
      th = Thread.new { Thread.current[:cat] = 'meow' }
      th.join
      var = :not_updated
      th.fetch(:cat) { var = :updated }.should == 'meow'
      var.should == :not_updated
    end

    it "uses the block if a default is given and warns about it" do
      th = Thread.new {}
      th.join
      -> {
        th.fetch(:cat, false) { true }.should == true
      }.should complain(/warning: block supersedes default value argument/)
    end
  end

  it 'raises an ArgumentError when not passed one or two arguments' do
    -> { Thread.current.fetch() }.should raise_error(ArgumentError)
    -> { Thread.current.fetch(1, 2, 3) }.should raise_error(ArgumentError)
  end
end