Unexpected ruby minitest must_equal parsing silliness

poop.rb

require 'minitest/autorun'

class Poop < Minitest::Spec
  def subject
    {}
  end

  describe 'silliness' do
    it 'is an empty hash' do
      subject.must_equal {}
    end

    it 'is an empty hash in parens' do
      subject.must_equal({})
    end
  end
end

poop_output.txt

$ ruby poop.rb
Run options: --seed 60711

# Running:

F.

Finished in 0.029188s, 68.5213 runs/s, 68.5213 assertions/s.

  1) Failure:
silliness#test_0001_is an empty hash [poop.rb:10]:
Expected: nil
  Actual: {}

2 runs, 2 assertions, 1 failures, 0 errors, 0 skips

whats_happening.rb

def method_with_splat(*args, &block)
  puts "args = #{args.inspect}"
  puts "block = #{block.inspect}"
end

def method_without_splat(args, &block)
  puts "args = #{args.inspect}"
  puts "block = #{block.inspect}"
end

puts "with splat:"
method_with_splat {}
method_with_splat({})
puts "without splat:"
# method_without_splat {} # This causes an argument error
method_without_splat({})

whats_happening_output.txt

with splat:
args = []
block = #<Proc:[email protected]:12>
args = [{}]
block = nil
without splat:
args = {}
block = nil