Add specs for Exception#detailed_message

[AI-Mozi]

#1016
[Feature #18564]

Exception#detailed_message has been added.
The default error printer calls this method on the Exception object
instead of #message

[AI-Mozi]

I'm not sure if thats enough. Adding more cases with different errors messages (like what I wrote) imo is not necessary, but maybe an example of creating new error class, with custom #detailed_message?

[andrykonchin]

I would propose the following test cases:

• it returns decorated message - message and exception class name
• it accepts highlight keyword argument and adds escape control sequences (or some similar description)
• it allows and ignores other keyword arguments
• it just returns a message if exception class is anonymous
  • I mean the following case - Class.new(RuntimeError).new("message").detailed_message # => message
• it returns "unhandled exception" when for an instance of RuntimeError with empty message`
  • I mean the following case - RuntimeError.new("").detailed_message # => unhandled exception)
• returns just a class name for an instance of RuntimeError subclass with empty message
  • C = Class.new(RuntimeError); C.new("").detailed_message # => "C"
• it returns a generated ... (class name?) for an instance of RuntimeError anonymous subclass with empty message
  • klass = Class.new(RuntimeError); klass.new("").detailed_message # => "#<Class:0x000000010ba06228>"

Also the behaviour of #full_message is changed, so the following cases could be added as well:

• it relies on #detailed_message
  • so here we can redefine a detailed_message message and demonstrate its value is printed by #full_message
• it passes all its own keyword arguments to #detailed_message

Original PR with some MRI specs - ruby/ruby#5516

[AI-Mozi]

Is C enough, or should it be more meaningful?

[andrykonchin]

Yeap, it's OK. There are a lot of helper classes like A, B, M etc with short names for readability (I suppose)

[andrykonchin]

Suggested change

	it "allows and ingores other keyword arguments" do
	it "allows and ignores other keyword arguments" do

[AI-Mozi]

Ehh.. these typos everywhere.. sorry

[andrykonchin]

Thank you for new specs!