Added tests for _waitForElementByTimeout function

src/util/waitForElement.js

@@ -28,7 +28,7 @@ export default function _waitForElement(elSelector, callback) {
     });
   } else {
     // Old browsers will wait by timeout
-    waitForElementByTimeout(elSelector, callback, 1000, 10000);
+    _waitForElementByTimeout(elSelector, callback, 1000, 10000);
   }
 }
 
@@ -38,7 +38,7 @@ export default function _waitForElement(elSelector, callback) {
  * @param {number} checkInterval In milliseconds
  * @param {number} maxTimeout In milliseconds
  */
-function waitForElementByTimeout(
+export function _waitForElementByTimeout(
   elSelector,
   callback,
   checkInterval,

tests/util/waitForElement.test.js

@@ -0,0 +1,59 @@
+import { _waitForElementByTimeout } from "../../src/util/waitForElement";
+import { appendDummyElement } from "../helper";
+
+describe("Testing _waitForElementByTimeout", () => {
+  const interval = 100;
+  const maxTimeout = 3000;
+
+  test("Callback call even if element doesn't appear after timeout", (done) => {
+    const callback = jest.fn();
+    _waitForElementByTimeout("#not_existed", callback, interval, maxTimeout);
+    expect(callback).toBeCalledTimes(0);
+    setTimeout(function () {
+      expect(callback).toBeCalledTimes(1);
+      done();
+    }, maxTimeout + interval);
+  });
+
+  test("Callback should be called immediately if elements already exists", () => {
+    const callback = jest.fn();
+    const id = "prev_created";
+    const el = appendDummyElement();
+    el.setAttribute("id", id);
+    _waitForElementByTimeout("#" + id, callback, interval, maxTimeout);
+    expect(callback).toBeCalledTimes(1);
+  });
+
+  test("Callback must be called after the element appears", (done) => {
+    const callback = jest.fn();
+    const id = "later_created";
+    _waitForElementByTimeout("#" + id, callback, interval, maxTimeout);
+    expect(callback).toBeCalledTimes(0);
+    const el = appendDummyElement();
+    el.setAttribute("id", id);
+    setTimeout(function () {
+      expect(callback).toBeCalledTimes(1);
+      done();
+    }, interval);
+  });
+
+  test("Check interval is bigger than maximum timeout", (done) => {
+    _waitForElementByTimeout("#not_existed", done, 1000, 100);
+  });
+
+  test("Check interval is equal to maximum timeout", (done) => {
+    _waitForElementByTimeout("#not_existed", done, 1000, 1000);
+  });
+
+  test("Check interval is zero", (done) => {
+    _waitForElementByTimeout("#not_existed", done, 0, maxTimeout);
+  });
+
+  test("Maximum timeout is zero", (done) => {
+    _waitForElementByTimeout("#not_existed", done, interval, 0);
+  });
+
+  test("Maximum timeout and interval are zero", (done) => {
+    _waitForElementByTimeout("#not_existed", done, 0, 0);
+  });
+});