ruby – 为什么assert_equal的格式/语法与其他assert_equals不同

我正在通过 Ruby Koans的工作,目前在AboutHash上.到此为止,assert_equals遵循以下特定的格式化样式：assert_equal space expected_value逗号实际值(例如assert_equal 2,11).但是,关于Hash中的test_creating_hashes def有一个assert_equal,它不遵循此模式,如果我将其更改为匹配该模式,那么它将失败.特别：

def test_creating_hashes
  empty_hash = Hash.new
  assert_equal {},empty_hash  # --> fails 
  assert_equal({},empty_hash) # --> passes  
end

那么在这种情况下,assert_equal有什么特别之处？

测试失败消息的肉是：

<internal:lib/rubygems/custom_require>:29:in `require':    /Ruby_on_Rails/koans/about_hashes.rb:7: syntax error,unexpected ',',expecting keyword_end (SyntaxError)
assert_equal {},empty_hash #{} are also used for blocks
                ^
from <internal:lib/rubygems/custom_require>:29:in `require'
from path_to_enlightenment.rb:10:in `<main>'

def t(arg1,arg2)
  p arg1
end


ruby-1.9.2-p136 :057 > t {}
ArgumentError: wrong number of arguments (0 for 2)
ruby-1.9.2-p136 :056 > t {},arg2
SyntaxError: (irb):56: syntax error,expecting $end
t {},arg2