spec/ruby/core/fiber/yield_spec.rb


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require_relative '../../spec_helper'

describe "Fiber.yield" do
  it "passes control to the Fiber's caller" do
    step = 0
    fiber = Fiber.new { step = 1; Fiber.yield; step = 2; Fiber.yield; step = 3 }
    fiber.resume
    step.should == 1
    fiber.resume
    step.should == 2
  end

  it "returns its arguments to the caller" do
    fiber = Fiber.new { true; Fiber.yield :glark; true }
    fiber.resume.should == :glark
    fiber.resume
  end

  it "returns nil to the caller if given no arguments" do
    fiber = Fiber.new { true; Fiber.yield; true }
    fiber.resume.should be_nil
    fiber.resume
  end

  it "returns to the Fiber the value of the #resume call that invoked it" do
    fiber = Fiber.new { Fiber.yield.should == :caller }
    fiber.resume
    fiber.resume :caller
  end

  it "does not propagate or reraise a rescued exception" do
    fiber = Fiber.new do
      begin
        raise "an error in a Fiber"
      rescue
        Fiber.yield :first
      end

      :second
    end

    fiber.resume.should == :first
    fiber.resume.should == :second
  end

  it "raises a FiberError if called from the root Fiber" do
    ->{ Fiber.yield }.should raise_error(FiberError)
  end
end