add failure threshold

Author: hollandjake

tests/visual/helpers.js

@@ -26,7 +26,7 @@ function runDocTest(options, fn) {
             const { systemFonts = false } = options;
             const images = await pdf2png(pdfData, { systemFonts });
             for (let image of images) {
-              expect(image).toMatchImageSnapshot();
+              expect(image).toMatchImageSnapshot(options);
             }
             resolve();
           } catch (err) {

tests/visual/text.spec.js

@@ -184,7 +184,7 @@ describe('text', function () {
   });
 
   test('bounded text precision', function () {
-    return runDocTest({ systemFonts: true }, function (doc) {
+    return runDocTest({ systemFonts: true, failureThreshold: 0.05, failureThresholdType: 'percent' }, function (doc) {
       const text = 'New york';
       const bounds = doc.boundsOfString(text);
       doc