Workaround for false negatives for exactly matching images

Author: martinleopold

test/unit/visual/visualTest.js

@@ -59,6 +59,11 @@ window.checkMatch = function(actual, expected, p5) {
       Math.ceil(img.height * scale)
     );
   }
+  // The below algorithm to calculate differences can produce false negatives in certain cases.
+  // Immediately return true for exact matches.
+  if (toBase64(expected) === toBase64(actual)) {
+    return { ok: true };
+  }
   const diff = p5.createImage(actual.width, actual.height);
   diff.drawingContext.drawImage(actual.canvas, 0, 0);
   diff.drawingContext.globalCompositeOperation = 'difference';