[Telemetry Tables] Make sure tables auto scroll correctly on first load (#7720)

* run scroll method to scroll to top after initial load of historical data

* clarifying comment

* added e2e test to make sure tables auto scroll on mount

* adding descriptive comments

* adding in ascending check as well

* added new appAction for navigating to/in realtime, using it in table scroll test

* lint

---------

Co-authored-by: David Tsay <3614296+davetsay@users.noreply.github.com>

e2e/appActions.js

@@ -275,6 +275,17 @@ async function navigateToObjectWithFixedTimeBounds(page, url, start, end) {
   );
 }
 
+/**
+ * Navigates directly to a given object url, in real-time mode.
+ * @param {import('@playwright/test').Page} page
+ * @param {string} url The url to the domainObject
+ */
+async function navigateToObjectWithRealTime(page, url, start = '1800000', end = '30000') {
+  await page.goto(
+    `${url}?tc.mode=local&tc.startDelta=${start}&tc.endDelta=${end}&tc.timeSystem=utc`
+  );
+}
+
 /**
  * Open the given `domainObject`'s context menu from the object tree.
  * Expands the path to the object and scrolls to it if necessary.
@@ -656,6 +667,7 @@ export {
   getFocusedObjectUuid,
   getHashUrlToDomainObject,
   navigateToObjectWithFixedTimeBounds,
+  navigateToObjectWithRealTime,
   openObjectTreeContextMenu,
   renameObjectFromContextMenu,
   setEndOffset,

e2e/tests/functional/plugins/telemetryTable/telemetryTable.e2e.spec.js

@@ -22,8 +22,8 @@
 
 import {
   createDomainObjectWithDefaults,
-  setTimeConductorBounds,
-  setTimeConductorMode
+  navigateToObjectWithRealTime,
+  setTimeConductorBounds
 } from '../../../../appActions.js';
 import { expect, test } from '../../../../pluginFixtures.js';
 
@@ -39,12 +39,52 @@ test.describe('Telemetry Table', () => {
       type: 'Sine Wave Generator',
       parent: table.uuid
     });
-    await page.goto(table.url);
-    await setTimeConductorMode(page, false);
+    await navigateToObjectWithRealTime(page, table.url);
     const rows = page.getByLabel('table content').getByLabel('Table Row');
     await expect(rows).toHaveCount(50);
   });
 
+  test('on load, auto scrolls to top for descending, and to bottom for ascending', async ({
+    page
+  }) => {
+    const sineWaveGenerator = await createDomainObjectWithDefaults(page, {
+      type: 'Sine Wave Generator',
+      parent: table.uuid
+    });
+
+    // verify in telemetry table object view
+    await navigateToObjectWithRealTime(page, table.url);
+
+    expect(await getScrollPosition(page)).toBe(0);
+
+    // verify in telemetry table view
+    await page.goto(sineWaveGenerator.url);
+    await page.getByLabel('Open the View Switcher Menu').click();
+    await page.getByText('Telemetry Table', { exact: true }).click();
+
+    expect(await getScrollPosition(page)).toBe(0);
+
+    // navigate back to table
+    await page.goto(table.url);
+
+    // go into edit mode
+    await page.getByLabel('Edit Object').click();
+
+    // change sort direction
+    await page.locator('thead div').filter({ hasText: 'Time' }).click();
+
+    // save view
+    await page.getByRole('button', { name: 'Save' }).click();
+    await page.getByRole('listitem', { name: 'Save and Finish Editing' }).click();
+
+    // navigate away and back
+    await page.goto(sineWaveGenerator.url);
+    await page.goto(table.url);
+
+    // verify scroll position
+    expect(await getScrollPosition(page, false)).toBeLessThan(1);
+  });
+
   test('unpauses and filters data when paused by button and user changes bounds', async ({
     page
   }) => {
@@ -183,3 +223,42 @@ test.describe('Telemetry Table', () => {
     await page.click('button[title="Pause"]');
   });
 });
+
+async function getScrollPosition(page, top = true) {
+  const tableBody = page.locator('.c-table__body-w');
+
+  // Wait for the scrollbar to appear
+  await tableBody.evaluate((node) => {
+    return new Promise((resolve) => {
+      function checkScroll() {
+        if (node.scrollHeight > node.clientHeight) {
+          resolve();
+        } else {
+          setTimeout(checkScroll, 100);
+        }
+      }
+      checkScroll();
+    });
+  });
+
+  // make sure there are rows
+  const rows = page.getByLabel('table content').getByLabel('Table Row');
+  await rows.first().waitFor();
+
+  // Using this to allow for rows to come and go, so we can truly test the scroll position
+  // eslint-disable-next-line playwright/no-wait-for-timeout
+  await page.waitForTimeout(1000);
+
+  const { scrollTop, clientHeight, scrollHeight } = await tableBody.evaluate((node) => ({
+    scrollTop: node.scrollTop,
+    clientHeight: node.clientHeight,
+    scrollHeight: node.scrollHeight
+  }));
+
+  // eslint-disable-next-line playwright/no-conditional-in-test
+  if (top) {
+    return scrollTop;
+  } else {
+    return Math.abs(scrollHeight - (scrollTop + clientHeight));
+  }
+}

src/plugins/telemetryTable/components/TableComponent.vue

@@ -561,6 +561,9 @@ export default {
 
     this.table.initialize();
     this.rescaleToContainer();
+
+    // Scroll to the top of the table after loading
+    this.addToAfterLoadActions(this.scroll);
   },
   beforeUnmount() {
     this.table.off('object-added', this.addObject);