yield_spec.rb

require_relative '../spec_helper'
require_relative 'fixtures/yield'

# Note that these specs use blocks defined as { |*a| ... } to capture the
# arguments with which the block is invoked. This is slightly confusing
# because the outer Array is a consequence of |*a| but it is necessary to
# clearly distinguish some behaviors.

describe "The yield call" do
  before :each do
    @y = YieldSpecs::Yielder.new
  end

  describe "taking no arguments" do
    it "raises a LocalJumpError when the method is not passed a block" do
      -> { @y.z }.should raise_error(LocalJumpError)
    end

    it "ignores assignment to the explicit block argument and calls the passed block" do
      @y.ze { 42 }.should == 42
    end

    it "does not pass a named block to the block being yielded to" do
      @y.z() { |&block| block == nil }.should == true
    end
  end

  describe "taking a single argument" do
    describe "when no block is given" do
      it "raises a LocalJumpError" do
        -> { @y.s(1) }.should raise_error(LocalJumpError)
      end
    end

    describe "yielding to a literal block" do
      it "passes an empty Array when the argument is an empty Array" do
        @y.s([]) { |*a| a }.should == [[]]
      end

      it "passes nil as a value" do
        @y.s(nil) { |*a| a }.should == [nil]
      end

      it "passes a single value" do
        @y.s(1) { |*a| a }.should == [1]
      end

      it "passes a single, multi-value Array" do
        @y.s([1, 2, 3]) { |*a| a }.should == [[1, 2, 3]]
      end
    end

    describe "yielding to a lambda" do
      it "passes an empty Array when the argument is an empty Array" do
        @y.s([], &-> *a { a }).should == [[]]
      end

      it "passes nil as a value" do
        @y.s(nil, &-> *a { a }).should == [nil]
      end

      it "passes a single value" do
        @y.s(1, &-> *a { a }).should == [1]
      end

      it "passes a single, multi-value Array" do
        @y.s([1, 2, 3], &-> *a { a }).should == [[1, 2, 3]]
      end

      it "raises an ArgumentError if too few arguments are passed" do
        -> {
          @y.s(1, &-> a, b { [a,b] })
        }.should raise_error(ArgumentError)
      end

      it "should not destructure an Array into multiple arguments" do
        -> {
          @y.s([1, 2], &-> a, b { [a,b] })
        }.should raise_error(ArgumentError)
      end
    end
  end

  describe "taking multiple arguments" do
    it "raises a LocalJumpError when the method is not passed a block" do
      -> { @y.m(1, 2, 3) }.should raise_error(LocalJumpError)
    end

    it "passes the arguments to the block" do
      @y.m(1, 2, 3) { |*a| a }.should == [1, 2, 3]
    end

    it "passes only the first argument if the block takes one parameter" do
      @y.m(1, 2, 3) { |a| a }.should == 1
    end

    it "raises an ArgumentError if too many arguments are passed to a lambda" do
      -> {
        @y.m(1, 2, 3, &-> a { })
      }.should raise_error(ArgumentError)
    end

    it "raises an ArgumentError if too few arguments are passed to a lambda" do
      -> {
        @y.m(1, 2, 3, &-> a, b, c, d { })
      }.should raise_error(ArgumentError)
    end
  end

  describe "taking a single splatted argument" do
    it "raises a LocalJumpError when the method is not passed a block" do
      -> { @y.r(0) }.should raise_error(LocalJumpError)
    end

    it "passes a single value" do
      @y.r(1) { |*a| a }.should == [1]
    end

    it "passes no arguments when the argument is an empty Array" do
      @y.r([]) { |*a| a }.should == []
    end

    it "passes the value when the argument is an Array containing a single value" do
      @y.r([1]) { |*a| a }.should == [1]
    end

    it "passes the values of the Array as individual arguments" do
      @y.r([1, 2, 3]) { |*a| a }.should == [1, 2, 3]
    end

    it "passes the element of a single element Array" do
      @y.r([[1, 2]]) { |*a| a }.should == [[1, 2]]
      @y.r([nil]) { |*a| a }.should == [nil]
      @y.r([[]]) { |*a| a }.should == [[]]
    end

    it "passes no values when give nil as an argument" do
      @y.r(nil) { |*a| a }.should == []
    end
  end

  describe "taking multiple arguments with a splat" do
    it "raises a LocalJumpError when the method is not passed a block" do
      -> { @y.rs(1, 2, [3, 4]) }.should raise_error(LocalJumpError)
    end

    it "passes the arguments to the block" do
      @y.rs(1, 2, 3) { |*a| a }.should == [1, 2, 3]
    end

    it "does not pass an argument value if the splatted argument is an empty Array" do
      @y.rs(1, 2, []) { |*a| a }.should == [1, 2]
    end

    it "passes the Array elements as arguments if the splatted argument is a non-empty Array" do
      @y.rs(1, 2, [3]) { |*a| a }.should == [1, 2, 3]
      @y.rs(1, 2, [nil]) { |*a| a }.should == [1, 2, nil]
      @y.rs(1, 2, [[]]) { |*a| a }.should == [1, 2, []]
      @y.rs(1, 2, [3, 4, 5]) { |*a| a }.should == [1, 2, 3, 4, 5]
    end

    it "does not pass an argument value if the splatted argument is nil" do
      @y.rs(1, 2, nil) { |*a| a }.should == [1, 2]
    end
  end

  describe "taking matching arguments with splats and post args" do
    it "raises a LocalJumpError when the method is not passed a block" do
      -> { @y.rs(1, 2, [3, 4]) }.should raise_error(LocalJumpError)
    end

    it "passes the arguments to the block" do
      @y.rs([1, 2], 3, 4) { |(*a, b), c, d| [a, b, c, d] }.should == [[1], 2, 3, 4]
    end
  end

  describe "taking a splat and a keyword argument" do
    it "passes it as an array of the values and a hash" do
      @y.k([1, 2]) { |*a| a }.should == [1, 2, {:b=>true}]
    end
  end

  it "uses captured block of a block used in define_method" do
    @y.deep(2).should == 4
  end
end

describe "Using yield in a singleton class literal" do
  ruby_version_is ""..."3.0" do
    it 'emits a deprecation warning' do
      code = <<~RUBY
        def m
          class << Object.new
            yield
          end
        end
        m { :ok }
      RUBY

      -> { eval(code) }.should complain(/warning: `yield' in class syntax will not be supported from Ruby 3.0/)
    end
  end

  ruby_version_is "3.0" do
    it 'raises a SyntaxError' do
      code = <<~RUBY
        class << Object.new
          yield
        end
      RUBY

      -> { eval(code) }.should raise_error(SyntaxError, /Invalid yield/)
    end
  end
end

describe "Using yield in non-lambda block" do
  it 'raises a SyntaxError' do
    code = <<~RUBY
        1.times { yield }
      RUBY

    -> { eval(code) }.should raise_error(SyntaxError, /Invalid yield/)
  end
end