From f0ebfea85844b915ac07554df31f11eea90fd29e Mon Sep 17 00:00:00 2001
From: Bonnie Zhou <bzbee003@gmail.com>
Date: Wed, 22 Aug 2018 13:45:48 -0700
Subject: [PATCH] fix(tab-bar): Early exit (#3386)

Move the early exit for activating a tab from Tab to TabBar.
---
 packages/mdc-tab-bar/foundation.js       | 7 ++-----
 packages/mdc-tab/foundation.js           | 5 -----
 test/unit/mdc-tab-bar/foundation.test.js | 9 +++++++++
 test/unit/mdc-tab/foundation.test.js     | 7 -------
 4 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/packages/mdc-tab-bar/foundation.js b/packages/mdc-tab-bar/foundation.js
index e902810cd00..9f3e3b1b24d 100644
--- a/packages/mdc-tab-bar/foundation.js
+++ b/packages/mdc-tab-bar/foundation.js
@@ -125,7 +125,7 @@ class MDCTabBarFoundation extends MDCFoundation {
    */
   activateTab(index) {
     const previousActiveIndex = this.adapter_.getActiveTabIndex();
-    if (!this.indexIsInRange_(index)) {
+    if (!this.indexIsInRange_(index) || index === previousActiveIndex) {
       return;
     }
 
@@ -133,10 +133,7 @@ class MDCTabBarFoundation extends MDCFoundation {
     this.adapter_.activateTabAtIndex(index, this.adapter_.getTabIndicatorClientRectAtIndex(previousActiveIndex));
     this.scrollIntoView(index);
 
-    // Only notify the tab activation if the index is different than the previously active index
-    if (index !== previousActiveIndex) {
-      this.adapter_.notifyTabActivated(index);
-    }
+    this.adapter_.notifyTabActivated(index);
   }
 
   /**
diff --git a/packages/mdc-tab/foundation.js b/packages/mdc-tab/foundation.js
index 868781a372d..6aee35e5232 100644
--- a/packages/mdc-tab/foundation.js
+++ b/packages/mdc-tab/foundation.js
@@ -98,11 +98,6 @@ class MDCTabFoundation extends MDCFoundation {
    * @param {!ClientRect=} previousIndicatorClientRect
    */
   activate(previousIndicatorClientRect) {
-    // Early exit
-    if (this.isActive()) {
-      return;
-    }
-
     this.adapter_.addClass(cssClasses.ACTIVE);
     this.adapter_.setAttr(strings.ARIA_SELECTED, 'true');
     this.adapter_.setAttr(strings.TABINDEX, '0');
diff --git a/test/unit/mdc-tab-bar/foundation.test.js b/test/unit/mdc-tab-bar/foundation.test.js
index 18969f518a1..3a81cf2c6a8 100644
--- a/test/unit/mdc-tab-bar/foundation.test.js
+++ b/test/unit/mdc-tab-bar/foundation.test.js
@@ -359,6 +359,15 @@ test('#activateTab() does nothing if the index underflows the tab list', () => {
   td.verify(mockAdapter.activateTabAtIndex(td.matchers.isA(Number)), {times: 0});
 });
 
+test('#activateTab() does nothing if the index is the same as the previous active index', () => {
+  const {foundation, mockAdapter} = setupActivateTabTest();
+  td.when(mockAdapter.getActiveTabIndex()).thenReturn(0);
+  td.when(mockAdapter.getTabListLength()).thenReturn(13);
+  foundation.activateTab(0);
+  td.verify(mockAdapter.deactivateTabAtIndex(td.matchers.isA(Number)), {times: 0});
+  td.verify(mockAdapter.activateTabAtIndex(td.matchers.isA(Number)), {times: 0});
+});
+
 test(`#activateTab() does not emit the ${MDCTabBarFoundation.strings.TAB_ACTIVATED_EVENT} event if the index` +
   ' is the currently active index', () => {
   const {foundation, mockAdapter} = setupActivateTabTest();
diff --git a/test/unit/mdc-tab/foundation.test.js b/test/unit/mdc-tab/foundation.test.js
index bfe07c386b6..1dfaf1b5ae7 100644
--- a/test/unit/mdc-tab/foundation.test.js
+++ b/test/unit/mdc-tab/foundation.test.js
@@ -51,13 +51,6 @@ test('defaultAdapter returns a complete adapter implementation', () => {
 
 const setupTest = () => setupFoundationTest(MDCTabFoundation);
 
-test('#activate does nothing if already active', () => {
-  const {foundation, mockAdapter} = setupTest();
-  td.when(mockAdapter.hasClass(MDCTabFoundation.cssClasses.ACTIVE)).thenReturn(true);
-  foundation.activate();
-  td.verify(mockAdapter.addClass(MDCTabFoundation.cssClasses.ACTIVE), {times: 0});
-});
-
 test('#activate adds mdc-tab--active class to the root element', () => {
   const {foundation, mockAdapter} = setupTest();
   foundation.activate();