trying to add util unit tests

spec/UtilSpec.js

@@ -0,0 +1,21 @@
+/* eslint-env mocha */
+
+describe('Util', function () {
+  it('should include the token in the sprite URL when the the URL does not start with http', function () {
+    const spriteUrl = "../sprites/sprite"
+    const token = "asdf";
+
+    const style = L.esri.Vector.Util.formatStyle({"version":8,"sprite":spriteUrl,"glyphs":"../fonts/{fontstack}/{range}.pbf","sources":{"esri":{"type":"vector","attribution":"test","bounds":[-180,-85.0511,180,85.0511],"minzoom":0,"maxzoom":19,"scheme":"xyz","url":"../../"}},"layers":[]}, "nope", {}, token);
+
+    expect(style.sprite).to.equal(`${spriteUrl}?token=${token}`);
+  });
+
+  it('should include the token in the sprite URL when the the URL does start with http', function () {
+    const spriteUrl = "https://www.arcgis.com/sharing/rest/content/items/123456789/resources/sprites/sprite-1679474043120"
+    const token = "asdf";
+
+    const style = L.esri.Vector.Util.formatStyle({"version":8,"sprite":spriteUrl,"glyphs":"../fonts/{fontstack}/{range}.pbf","sources":{"esri":{"type":"vector","attribution":"test","bounds":[-180,-85.0511,180,85.0511],"minzoom":0,"maxzoom":19,"scheme":"xyz","url":"../../"}},"layers":[]}, "nope", {}, token);
+
+    expect(style.sprite).to.equal(`${spriteUrl}?token=${token}`);
+  });
+});