Mock queueMicrotask in unit tests (#314)

* Update jest to support queueMircotask

* Do not use row.visibleElement in pdf

* Revert "Update jest to support queueMircotask"

This reverts commit a043c85.

* Mock queueMircotask in unit tests

jest.config.js

@@ -4,6 +4,7 @@ module.exports = {
       tsConfig: "tsconfig.test.json"
     }
   },
+  setupFiles: ["<rootDir>/setupFile.js"],
   reporters: [
     "default",
     [ "jest-junit", {

setupFile.js

@@ -0,0 +1 @@
+global.queueMicrotask = (cb) => { cb(); }

src/flat_layout/flat_survey.ts

@@ -70,12 +70,13 @@ export class FlatSurvey {
             const width: number = SurveyHelper.getPageAvailableWidth(controller);
             let nextMarginLeft: number = controller.margins.left;
             const rowFlats: IPdfBrick[] = [];
-            for (let i: number = 0; i < row.visibleElements.length; i++) {
-                let element: IElement = row.visibleElements[i];
+            const visibleElements = row.elements.filter(el => el.isVisible);
+            for (let i: number = 0; i < visibleElements.length; i++) {
+                let element: IElement = visibleElements[i];
                 if (!element.isVisible) continue;
                 const persWidth: number = SurveyHelper.parseWidth(element.renderWidth,
-                    width - (row.visibleElements.length - 1) * controller.unitWidth,
-                    row.visibleElements.length);
+                    width - (visibleElements.length - 1) * controller.unitWidth,
+                    visibleElements.length);
                 controller.margins.left = nextMarginLeft + ((i !== 0) ? controller.unitWidth : 0);
                 controller.margins.right = controller.paperWidth - controller.margins.left - persWidth;
                 currPoint.xLeft = controller.margins.left;