address #161 with linkReference test; update list-item snapshots

rules/list-item.js

@@ -110,9 +110,10 @@ function validateList(list, file) {
 
 		// Might have children like {image} {text} {link} - {descrition}
 		// Keep discarding elements until we find a link
-		if (link.type !== 'link') {
+		//                                       or linkReference
+		if (!/link/.test(link.type)) {
 			for (let i = 0; i < description.length - 1; i++) {
-				if (description[i].type === 'link') {
+				if (/link/.test(description[i].type)) {
 					link = description[i];
 					description = description.slice(i + 1);
 				}
@@ -128,6 +129,15 @@ function validateList(list, file) {
 }
 
 function validateListItemLink(link, file) {
+
+	// NB. need remark-lint-no-undefined-references separately
+	//     to catch if this is a valid reference. here we only care that it exists
+
+	if (link.type === 'linkReference') {
+		// TODO: need to test link children against listItemLinkNodeAllowList?
+		return true;
+	}
+
 	if (link.type !== 'link') {
 		file.message('Invalid list item link', link);
 		return false;

test/fixtures/list-item/0.md

@@ -136,6 +136,7 @@ These sub-lists use mixed indentation (spaces and tabs).
 - [why-is-node-running](https://github.com/mafintosh/why-is-node-running) - Node.js is running but you don't know why?
 
 
+- [gtkada] - Ada graphical toolkit based on Gtk3 components (issue #161 link reference below but checked by `remark-lint-no-undefined-references` not `rules/list-item.js`).
 - [foo](https://foo.com) ![stars](https://img.shields.io/github/stars/foo/foo.svg) - Valid description.
 - ![v3](img/vapor-3.png) [API Error Middleware](https://github.com/skelpo/APIErrorMiddleware) - Vapor middleware for converting thrown errors to JSON responses.
 - ![v2](img/vapor-2.png) ![v3](img/vapor-3.png) [Bugsnag](https://github.com/nodes-vapor/bugsnag) - Report errors with Bugsnag.
@@ -145,3 +146,5 @@ These sub-lists use mixed indentation (spaces and tabs).
 - [__Compiling machine learning programs via high-level tracing__. Roy Frostig, Matthew James Johnson, Chris Leary. _MLSys 2018_.](https://mlsys.org/Conferences/doc/2018/146.pdf) - This white paper describes an early version of JAX, detailing how computation is traced and compiled (issue #136)
 -->
 
+[gtkada]: https://github.com/AdaCore/gtkada
+

test/fixtures/list-item/1.md

@@ -70,3 +70,4 @@ Test description's ending punctuation.
 
 - [foo](https://foo.com) - Quote-inducing double punctuation “end…”??!
 - [foo](https://foo.com) - Quote-inducing double punctuation “end?…...”…...?
+- [gtkada] - reference link with no reference