chore(tabs): adds screenshot tests

PiperOrigin-RevId: 532182408

tabs/harness.ts

@@ -15,12 +15,20 @@ import {Tabs} from './lib/tabs.js';
 export class TabHarness extends Harness<Tab> {
   override async getInteractiveElement() {
     await this.element.updateComplete;
-    return this.element.querySelector<HTMLButtonElement|HTMLLinkElement>(
-        '.button')!;
+    return this.element.renderRoot
+        .querySelector<HTMLButtonElement|HTMLLinkElement>('.button')!;
   }
 
-  async isIndicatorShowing() {
+  private async completeIndicatorAnimation() {
     await this.element.updateComplete;
+    const animations = this.element.indicator.getAnimations();
+    for (const animation of animations) {
+      animation.finish();
+    }
+  }
+
+  async isIndicatorShowing() {
+    await this.completeIndicatorAnimation();
     const opacity = getComputedStyle(this.element.indicator)['opacity'];
     return opacity === '1';
   }
@@ -30,6 +38,17 @@ export class TabHarness extends Harness<Tab> {
  * Test harness for Tabs.
  */
 export class TabsHarness extends Harness<Tabs> {
+  // Note, Tabs interactive element is the interactive element of the
+  // selected tab.
+  override async getInteractiveElement() {
+    await this.element.updateComplete;
+    const selectedItemHarness =
+        (this.element.selectedItem as ElementWithHarness<Tab>).harness as
+            TabHarness ??
+        new TabHarness(this.element.selectedItem);
+    return await selectedItemHarness.getInteractiveElement();
+  }
+
   get harnessedItems() {
     // Test access to protected property
     // tslint:disable-next-line:no-dict-access-on-struct-type

tabs/lib/tab.ts

@@ -81,10 +81,6 @@ export class Tab extends LitElement {
 
   @state() private showRipple = false;
 
-  // whether or not selection state can be animated; used to avoid initial
-  // animation and becomes true one task after first update.
-  private canAnimate = false;
-
   constructor() {
     super();
     if (!isServer) {
@@ -125,13 +121,8 @@ export class Tab extends LitElement {
       </button>`;
   }
 
-  protected override async firstUpdated() {
-    await new Promise(requestAnimationFrame);
-    this.canAnimate = true;
-  }
-
   protected override updated(changed: PropertyValues) {
-    if (changed.has('selected') && this.shouldAnimate()) {
+    if (changed.has('selected') && !this.disabled) {
       this.animateSelected();
     }
   }
@@ -144,10 +135,6 @@ export class Tab extends LitElement {
     dispatchActivationClick(this.button);
   };
 
-  private shouldAnimate() {
-    return this.canAnimate && !this.disabled;
-  }
-
   private readonly getRipple = () => {
     this.showRipple = true;
     return this.ripple;

tabs/lib/tabs.ts

@@ -232,10 +232,6 @@ export class Tabs extends LitElement {
   }
 
   protected override async updated(changed: PropertyValues) {
-    // if there's no items, they may not be ready, so wait before syncronizing
-    if (this.items.length === 0) {
-      await new Promise(requestAnimationFrame);
-    }
     const itemsOrVariantChanged =
         changed.has('items') || changed.has('variant');
     // sync variant with items.
@@ -296,13 +292,20 @@ export class Tabs extends LitElement {
     this.requestUpdate();
   }
 
+  private async itemsUpdateComplete() {
+    for (const item of this.items) {
+      await item.updateComplete;
+    }
+    return true;
+  }
+
   // ensures the given item is visible in view; defaults to the selected item
   private async scrollItemIntoView(item = this.selectedItem) {
     if (!item) {
       return;
     }
     // wait for items to render.
-    await new Promise(requestAnimationFrame);
+    await this.itemsUpdateComplete();
     const isVertical = this.orientation === 'vertical';
     const offset = isVertical ? item.offsetTop : item.offsetLeft;
     const extent = isVertical ? item.offsetHeight : item.offsetWidth;
@@ -311,8 +314,11 @@ export class Tabs extends LitElement {
     const min = offset - this.scrollMargin;
     const max = offset + extent - hostExtent + this.scrollMargin;
     const to = Math.min(min, Math.max(max, scroll));
+    const behavior =
+        // type annotation because `instant` is valid but not included in type.
+        this.focusedItem !== undefined ? 'smooth' : 'instant' as ScrollBehavior;
     this.scrollTo({
-      behavior: 'smooth',
+      behavior,
       [isVertical ? 'left' : 'top']: 0,
       [isVertical ? 'top' : 'left']: to
     });

tabs/test/window_size.json

@@ -0,0 +1,13 @@
+{
+  "capabilities": {
+    "goog:chromeOptions": {
+      "args": ["--window-position=0,0", "--window-size=3400,2215"]
+    },
+    "moz:firefoxOptions": {
+      "args": ["-width=3400","-height=2215"]
+    }
+  },
+  "extension": {
+    "xvfbResolution": "3400x2215x24"
+  }
+}

tokens/_md-comp-tab.scss

@@ -24,7 +24,6 @@ $_default: (
   'md-sys-shape': md-sys-shape.values(),
   'md-sys-state': md-sys-state.values(),
   'md-sys-typescale': md-sys-typescale.values(),
-  'md-comp-divider': md-comp-divider.values(),
 );
 
 $supported-tokens: (
@@ -242,7 +241,7 @@ $unsupported-tokens: (
 
 // add tokens for divider / label-text
 @function _add-missing-tokens($tokens, $deps) {
-  $divider-tokens: map.get($deps, 'md-comp-divider');
+  $divider-tokens: md-comp-divider.values();
   @each $key, $value in $divider-tokens {
     $key: 'divider-#{$key}';
     $tokens: map.set($tokens, $key, $value);