adjust warning message

src/compiler/compile/nodes/Element.ts

@@ -516,13 +516,13 @@ export default class Element extends Node {
 			let has_caption;
 			const track = this.children.find((i: Element) => i.name === 'track');
 			if (track) {
-				has_caption = track.attributes.find(a => a.name === "kind" && a.get_static_value() === "captions");
+				has_caption = track.attributes.find(a => a.name === 'kind' && a.get_static_value() === 'captions');
 			}
 
 			if (!has_caption) {
 				component.warn(this, {
 					code: `a11y-media-has-caption`,
-					message: `A11y: Media elements such as <audio> and <video> must have a <track> for captions.`
+					message: `A11y: Media elements must have a <track kind="captions">`
 				});
 			}
 		}

test/validator/samples/a11y-media-has-caption/warnings.json

@@ -6,7 +6,7 @@
       "column": 15,
       "line": 2
     },
-    "message": "A11y: Media elements such as <audio> and <video> must have a <track> for captions.",
+    "message": "A11y: Media elements must have a <track kind=\"captions\">",
     "pos": 40,
     "start": {
       "character": 40,
@@ -21,7 +21,7 @@
       "column": 24,
       "line": 3
     },
-    "message": "A11y: Media elements such as <audio> and <video> must have a <track> for captions.",
+    "message": "A11y: Media elements must have a <track kind=\"captions\">",
     "pos": 56,
     "start": {
       "character": 56,