eskip testable example is incorrectly passing

[ameowlia]

👋 Hello,

I am investigating the golang issue: golang/go#48362, where testable examples are causing false positives when the output comment block is not the last comment block example.

I ran a parser against the top golang repos, including this repo, and I found this bug with one of your testable examples.

The TODO comment block should be moved before the output comment block like so:

func Example() {
	code := `
		// Skipper - Eskip:
		// a routing table document, containing multiple route definitions
		// route definition to a jsx page renderer
		route0:
			PathRegexp(/\.html$/) && HeaderRegexp("Accept", "text/html") ->
			modPath(/\.html$/, ".jsx") ->
			requestHeader("X-Type", "page") ->
			"https://render.example.org";
		route1: Path("/some/path") -> "https://backend-0.example.org"; // a simple route
		// route definition with a shunt (no backend address)
		route2: Path("/some/other/path") -> static("/", "/var/www") -> <shunt>;
		// route definition directing requests to an api endpoint
		route3:
			Method("POST") && Path("/api") ->
			requestHeader("X-Type", "ajax-post") ->
			"https://api.example.org";
		// route definition with a loopback to route2 (no backend address)
		route4: Path("/some/alternative/path") -> setPath("/some/other/path") -> <loopback>;
        // route definition which forwards rest of requests (no backend address)
		route5: * -> requestHeader("X-Type", "page") -> <forward>;
		`

	routes, err := eskip.Parse(code)
	if err != nil {
		log.Println(err)
		return
	}

	format := "%v: [match] -> [%v filter(s) ->] <%v> \"%v\"\n"
	fmt.Println("Parsed routes:")
	for _, r := range routes {
		fmt.Printf(format, r.Id, len(r.Filters), r.BackendType, r.Backend)
	}
	// TODO: try to represent this compressed output in a nicer way. This is is now somewhat confusing
	// considering that it looks almost like eskip but it isn't.

	// output:
	// Parsed routes:
	// route0: [match] -> [2 filter(s) ->] <network> "https://render.example.org"
	// route1: [match] -> [0 filter(s) ->] <network> "https://backend-0.example.org"
	// route2: [match] -> [1 filter(s) ->] <shunt> ""
	// route3: [match] -> [1 filter(s) ->] <network> "https://api.example.org"
	// route4: [match] -> [1 filter(s) ->] <loopback> ""


}

When I made this change, the example failed:

$ go test .
2021/09/21 19:54:18 parse failed after token >, position 1015: syntax error
--- FAIL: Example (0.00s)
got:

want:
Parsed routes:
route0: [match] -> [2 filter(s) ->] <network> "https://render.example.org"
route1: [match] -> [0 filter(s) ->] <network> "https://backend-0.example.org"
route2: [match] -> [1 filter(s) ->] <shunt> ""
route3: [match] -> [1 filter(s) ->] <network> "https://api.example.org"
route4: [match] -> [1 filter(s) ->] <loopback> ""
FAIL
FAIL    github.com/zalando/skipper/eskip        0.016s
FAIL

[AlexanderYastrebov]

@ameowlia Hello and thank you for detailed report and interesting bug. I have opened #1861 to fix the example.

[szuecs]

Thanks @ameowlia !!