feat(cdk/tree): implement typeahead for TreeKeyManager (#27202)

* feat(cdk/a11y): implement typeahead (needs test)

* feat(cdk/a11y): handle typeahead in keydown handler

* feat(cdk/a11y): fix typeahead build errors

* feat(cdk/a11y): add tests for typeahead

* feat(cdk/a11y): add TreeKeyManager to public a11y API

* fix(cdk/a11y): tree key manager build errors/weird merge

* feat(cdk/a11y): fix api goldens

* fix(cdk/a11y): fix tests

src/cdk/a11y/key-manager/tree-key-manager.spec.ts

@@ -15,6 +15,7 @@ import {QueryList} from '@angular/core';
 import {take} from 'rxjs/operators';
 import {TreeKeyManager, TreeKeyManagerItem} from './tree-key-manager';
 import {Observable, of as observableOf, Subscription} from 'rxjs';
+import {fakeAsync, tick} from '@angular/core/testing';
 
 class FakeBaseTreeKeyManagerItem {
   _isExpanded = false;
@@ -115,14 +116,19 @@ describe('TreeKeyManager', () => {
         FakeArrayTreeKeyManagerItem | FakeObservableTreeKeyManagerItem
       >;
 
+      let parentItem: FakeArrayTreeKeyManagerItem | FakeObservableTreeKeyManagerItem; // index 0
+      let childItem: FakeArrayTreeKeyManagerItem | FakeObservableTreeKeyManagerItem; // index 1
+      let childItemWithNoChildren: FakeArrayTreeKeyManagerItem | FakeObservableTreeKeyManagerItem; // index 3
+      let lastItem: FakeArrayTreeKeyManagerItem | FakeObservableTreeKeyManagerItem; // index 5
+
       beforeEach(() => {
         itemList = new QueryList<FakeArrayTreeKeyManagerItem | FakeObservableTreeKeyManagerItem>();
-        const parent1 = new itemParam.constructor('parent1');
-        const parent1Child1 = new itemParam.constructor('parent1Child1');
-        const parent1Child1Child1 = new itemParam.constructor('parent1Child1Child1');
-        const parent1Child2 = new itemParam.constructor('parent1Child2');
-        const parent2 = new itemParam.constructor('parent2');
-        const parent2Child1 = new itemParam.constructor('parent2Child1');
+        const parent1 = new itemParam.constructor('one');
+        const parent1Child1 = new itemParam.constructor('two');
+        const parent1Child1Child1 = new itemParam.constructor('three');
+        const parent1Child2 = new itemParam.constructor('four');
+        const parent2 = new itemParam.constructor('five');
+        const parent2Child1 = new itemParam.constructor('six');
 
         parent1._children = [parent1Child1, parent1Child2];
         parent1Child1._parent = parent1;
@@ -132,6 +138,11 @@ describe('TreeKeyManager', () => {
         parent2._children = [parent2Child1];
         parent2Child1._parent = parent2;
 
+        parentItem = parent1;
+        childItem = parent1Child1;
+        childItemWithNoChildren = parent1Child2;
+        lastItem = parent2Child1;
+
         itemList.reset([
           parent1,
           parent1Child1,
@@ -155,16 +166,12 @@ describe('TreeKeyManager', () => {
         keyManager.onClick(itemList.get(0)!);
 
         expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(0);
-        expect(keyManager.getActiveItem()?.getLabel())
-          .withContext('active item label')
-          .toBe('parent1');
+        expect(keyManager.getActiveItem()?.getLabel()).withContext('active item label').toBe('one');
         itemList.reset([new FakeObservableTreeKeyManagerItem('parent0'), ...itemList.toArray()]);
         itemList.notifyOnChanges();
 
         expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(1);
-        expect(keyManager.getActiveItem()?.getLabel())
-          .withContext('active item label')
-          .toBe('parent1');
+        expect(keyManager.getActiveItem()?.getLabel()).withContext('active item label').toBe('one');
       });
 
       describe('Key events', () => {
@@ -728,6 +735,217 @@ describe('TreeKeyManager', () => {
           });
         }
       });
+
+      describe('typeahead mode', () => {
+        const debounceInterval = 300;
+
+        beforeEach(() => {
+          keyManager = new TreeKeyManager({
+            items: itemList,
+            typeAheadDebounceInterval: debounceInterval,
+          });
+        });
+
+        it('should throw if the items do not implement the getLabel method', () => {
+          const invalidQueryList = new QueryList<any>();
+          invalidQueryList.reset([{disabled: false}]);
+
+          expect(
+            () =>
+              new TreeKeyManager({
+                items: invalidQueryList,
+                typeAheadDebounceInterval: true,
+              }),
+          ).toThrowError(/must implement/);
+        });
+
+        it('should debounce the input key presses', fakeAsync(() => {
+          keyManager.onKeydown(createKeyboardEvent('keydown', 79, 'o')); // types "o"
+          tick(1);
+          keyManager.onKeydown(createKeyboardEvent('keydown', 78, 'n')); // types "n"
+          tick(1);
+          keyManager.onKeydown(createKeyboardEvent('keydown', 69, 'e')); // types "e"
+
+          expect(keyManager.getActiveItemIndex())
+            .withContext('active item index, before debounce interval')
+            .not.toBe(0);
+
+          tick(debounceInterval - 1);
+
+          expect(keyManager.getActiveItemIndex())
+            .withContext('active item index, after partial debounce interval')
+            .not.toBe(0);
+
+          tick(1);
+
+          expect(keyManager.getActiveItemIndex())
+            .withContext('active item index, after full debounce interval')
+            .toBe(0);
+        }));
+
+        it('uses a default debounce interval', fakeAsync(() => {
+          const defaultInterval = 200;
+          keyManager = new TreeKeyManager({
+            items: itemList,
+            typeAheadDebounceInterval: true,
+          });
+
+          keyManager.onKeydown(createKeyboardEvent('keydown', 79, 'o')); // types "o"
+          tick(1);
+          keyManager.onKeydown(createKeyboardEvent('keydown', 78, 'n')); // types "n"
+          tick(1);
+          keyManager.onKeydown(createKeyboardEvent('keydown', 69, 'e')); // types "e"
+
+          expect(keyManager.getActiveItemIndex())
+            .withContext('active item index, before debounce interval')
+            .not.toBe(0);
+
+          tick(defaultInterval - 1);
+
+          expect(keyManager.getActiveItemIndex())
+            .withContext('active item index, after partial debounce interval')
+            .not.toBe(0);
+
+          tick(1);
+
+          expect(keyManager.getActiveItemIndex())
+            .withContext('active item index, after full debounce interval')
+            .toBe(0);
+        }));
+
+        it('should focus the first item that starts with a letter', fakeAsync(() => {
+          keyManager.onKeydown(createKeyboardEvent('keydown', 84, 't')); // types "t"
+
+          tick(debounceInterval);
+
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(1);
+        }));
+
+        it('should focus the first item that starts with sequence of letters', fakeAsync(() => {
+          keyManager.onKeydown(createKeyboardEvent('keydown', 84, 't')); // types "t"
+          keyManager.onKeydown(createKeyboardEvent('keydown', 72, 'h')); // types "h"
+
+          tick(debounceInterval);
+
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(2);
+        }));
+
+        it('should cancel any pending timers if a navigation key is pressed', fakeAsync(() => {
+          keyManager.onKeydown(createKeyboardEvent('keydown', 84, 't')); // types "t"
+          keyManager.onKeydown(createKeyboardEvent('keydown', 72, 'h')); // types "h"
+          keyManager.onKeydown(fakeKeyEvents.downArrow);
+
+          tick(debounceInterval);
+
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(0);
+        }));
+
+        it('should handle non-English input', fakeAsync(() => {
+          itemList.reset([
+            new itemParam.constructor('едно'),
+            new itemParam.constructor('две'),
+            new itemParam.constructor('три'),
+          ]);
+          itemList.notifyOnChanges();
+
+          const keyboardEvent = createKeyboardEvent('keydown', 68, 'д');
+
+          keyManager.onKeydown(keyboardEvent); // types "д"
+          tick(debounceInterval);
+
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(1);
+        }));
+
+        it('should handle non-letter characters', fakeAsync(() => {
+          itemList.reset([
+            new itemParam.constructor('[]'),
+            new itemParam.constructor('321'),
+            new itemParam.constructor('`!?'),
+          ]);
+          itemList.notifyOnChanges();
+
+          keyManager.onKeydown(createKeyboardEvent('keydown', 192, '`')); // types "`"
+          tick(debounceInterval);
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(2);
+
+          keyManager.onKeydown(createKeyboardEvent('keydown', 51, '3')); // types "3"
+          tick(debounceInterval);
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(1);
+
+          keyManager.onKeydown(createKeyboardEvent('keydown', 219, '[')); // types "["
+          tick(debounceInterval);
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(0);
+        }));
+
+        it('should not focus disabled items', fakeAsync(() => {
+          expect(keyManager.getActiveItemIndex()).withContext('initial active item index').toBe(-1);
+
+          parentItem.isDisabled = true;
+
+          keyManager.onKeydown(createKeyboardEvent('keydown', 79, 'o')); // types "o"
+          tick(debounceInterval);
+
+          expect(keyManager.getActiveItemIndex()).withContext('initial active item index').toBe(-1);
+        }));
+
+        it('should start looking for matches after the active item', fakeAsync(() => {
+          const frodo = new itemParam.constructor('Frodo');
+          itemList.reset([
+            new itemParam.constructor('Bilbo'),
+            frodo,
+            new itemParam.constructor('Pippin'),
+            new itemParam.constructor('Boromir'),
+            new itemParam.constructor('Aragorn'),
+          ]);
+          itemList.notifyOnChanges();
+
+          keyManager.onClick(frodo);
+          keyManager.onKeydown(createKeyboardEvent('keydown', 66, 'b'));
+          tick(debounceInterval);
+
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(3);
+        }));
+
+        it('should wrap back around if there were no matches after the active item', fakeAsync(() => {
+          const boromir = new itemParam.constructor('Boromir');
+          itemList.reset([
+            new itemParam.constructor('Bilbo'),
+            new itemParam.constructor('Frodo'),
+            new itemParam.constructor('Pippin'),
+            boromir,
+            new itemParam.constructor('Aragorn'),
+          ]);
+          itemList.notifyOnChanges();
+
+          keyManager.onClick(boromir);
+          keyManager.onKeydown(createKeyboardEvent('keydown', 66, 'b'));
+          tick(debounceInterval);
+
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(0);
+        }));
+
+        it('should wrap back around if the last item is active', fakeAsync(() => {
+          keyManager.onClick(lastItem);
+          keyManager.onKeydown(createKeyboardEvent('keydown', 79, 'o'));
+          tick(debounceInterval);
+
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(0);
+        }));
+
+        it('should be able to select the first item', fakeAsync(() => {
+          keyManager.onKeydown(createKeyboardEvent('keydown', 79, 'o'));
+          tick(debounceInterval);
+
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(0);
+        }));
+
+        it('should not do anything if there is no match', fakeAsync(() => {
+          keyManager.onKeydown(createKeyboardEvent('keydown', 87, 'w'));
+          tick(debounceInterval);
+
+          expect(keyManager.getActiveItemIndex()).withContext('active item index').toBe(-1);
+        }));
+      });
     });
   }
 });