Incorrect output for the to_s method of Attribute AST nodes

[olbat]

I was playing around with the Crystal's parser and got this issue:

$ cat test.cr
require "compiler/crystal/syntax"
ast = Crystal::Parser.parse(%{@[Test(1, 2, n1: 1, n2: 2)]})
puts code = ast.to_s
Crystal::Parser.parse(code)


$ crystal run test.cr
@[Test(1, 2, n1: 1n2: 2)]
expecting token ')', not 'n2' (Crystal::SyntaxException)
0x4e0937: ??? at /opt/crystal/src/compiler/crystal/syntax/lexer.cr 2711:9
0x4e0907: ??? at /opt/crystal/src/compiler/crystal/syntax/lexer.cr 2710:5
0x4e33ec: *Crystal::Parser#check<Symbol>:Nil at /opt/crystal/src/compiler/crystal/syntax/parser.cr 5353:7
0x50dce2: *Crystal::Parser#parse_attribute:Crystal::Attribute at /opt/crystal/src/compiler/crystal/syntax/parser.cr 1182:15
...


$ crystal --version
Crystal 0.21.0 [c2c2276] (2017-02-21)

I think there must be something wrong with the to_s method of Attribute AST nodes: a comma is missing between the two named arguments ...

[olbat]

I tried to come with a fix #4099, just le me know if I did something wrong.

I also noticed that there is very few tests of the output to_s on C bindings-related AST nodes in the spec, should I add some at the same time ?

[RX14]

@olbat I'm sure more specs are always welcome!

[olbat]

Done !