Fix random test failures (#546)

Author: kurkle

package.json

@@ -19,6 +19,7 @@
   "scripts": {
     "build": "rollup -c",
     "dev": "karma start --auto-watch --no-single-run --browsers chrome",
+    "dev:ff": "karma start --auto-watch --no-single-run --browsers firefox",
     "docs": "npm run build && vuepress build docs --no-cache",
     "docs:dev": "npm run build && vuepress dev docs --no-cache",
     "lint": "concurrently \"npm:lint-*\"",

src/helpers/helpers.canvas.js

@@ -42,7 +42,7 @@ export function measureLabelSize(ctx, options) {
   }
   const font = toFont(options.font);
   const lines = isArray(content) ? content : [content];
-  const mapKey = lines.join() + font.string;
+  const mapKey = lines.join() + font.string + (ctx._measureText ? '-spriting' : '');
   if (!widthCache.has(mapKey)) {
     ctx.save();
     ctx.font = font.string;

test/fixtures/label/boxLocation.js

@@ -1,5 +1,6 @@
 module.exports = {
-  tolerance: 0.0170,
+  threshold: 0.2,
+  tolerance: 0.0071,
   config: {
     type: 'scatter',
     options: {