Fix accessibility of date sliders by adding aria-labels

(cherry picked from commit 2a881791ba)

cypress/e2e/my-dspace.cy.ts

@@ -22,15 +22,11 @@ describe('My DSpace page', () => {
         testA11y(
             {
                 include: ['ds-my-dspace-page'],
-                exclude: [
-                    ['nouislider'] // Date filter slider is missing ARIA labels. Will be fixed by #1175
-                ],
             },
             {
                 rules: {
-                    // Search filters fail these two "moderate" impact rules
+                    // Search filters fail this "moderate" impact rules
                     'heading-order': { enabled: false },
-                    'landmark-unique': { enabled: false }
                 }
             } as Options
         );

cypress/e2e/search-page.cy.ts

@@ -30,15 +30,11 @@ describe('Search Page', () => {
         testA11y(
             {
                 include: ['ds-search-page'],
-                exclude: [
-                    ['nouislider'] // Date filter slider is missing ARIA labels. Will be fixed by #1175
-                ],
             },
             {
                 rules: {
-                    // Search filters fail these two "moderate" impact rules
+                    // Search filters fail this "moderate" impact rule
                     'heading-order': { enabled: false },
-                    'landmark-unique': { enabled: false }
                 }
             } as Options
         );

src/app/shared/search/search-filters/search-filter/search-range-filter/search-range-filter.component.html

@@ -9,8 +9,8 @@
                   </span>
                   <input type="text" [(ngModel)]="range[0]" [name]="filterConfig.paramName + '.min'"
                          class="form-control" (blur)="onSubmit()"
-                         aria-label="Mininum value"
-                         [placeholder]="'search.filters.filter.' + filterConfig.name + '.min.placeholder' | translate"
+                         [attr.aria-label]="minLabel"
+                         [placeholder]="minLabel"
                   />
                 </label>
             </div>
@@ -21,8 +21,8 @@
                     </span>
                     <input type="text" [(ngModel)]="range[1]" [name]="filterConfig.paramName + '.max'"
                            class="form-control" (blur)="onSubmit()"
-                           aria-label="Maximum value"
-                           [placeholder]="'search.filters.filter.' + filterConfig.name + '.max.placeholder' | translate"
+                           [attr.aria-label]="maxLabel"
+                           [placeholder]="maxLabel"
                     />
                 </label>
             </div>
@@ -33,7 +33,7 @@
         </form>
 
         <ng-container *ngIf="shouldShowSlider()">
-            <nouislider [connect]="true" [min]="min" [max]="max" [step]="1"
+            <nouislider [connect]="true" [config]="config" [min]="min" [max]="max" [step]="1"
                         [dsDebounce]="250" (onDebounce)="onSubmit()"
                         (keydown)="startKeyboardControl()" (keyup)="stopKeyboardControl()"
                         [(ngModel)]="range" ngDefaultControl>

src/app/shared/search/search-filters/search-filter/search-range-filter/search-range-filter.component.ts

@@ -2,6 +2,7 @@ import { BehaviorSubject, combineLatest as observableCombineLatest, Subscription
 import { map, startWith } from 'rxjs/operators';
 import { isPlatformBrowser } from '@angular/common';
 import { Component, Inject, OnDestroy, OnInit, PLATFORM_ID } from '@angular/core';
+import { TranslateService } from '@ngx-translate/core';
 import { RemoteDataBuildService } from '../../../../../core/cache/builders/remote-data-build.service';
 import { FilterType } from '../../../models/filter-type.model';
 import { renderFacetFor } from '../search-filter-type-decorator';
@@ -53,11 +54,27 @@ export class SearchRangeFilterComponent extends SearchFacetFilterComponent imple
    */
   min = 1950;
 
+  /**
+   * i18n Label to use for minimum field
+   */
+  minLabel: string;
+
   /**
    * Fallback maximum for the range
    */
   max = new Date().getUTCFullYear();
 
+  /**
+   * i18n Label to use for maximum field
+   */
+  maxLabel: string;
+
+  /**
+   * Base configuration for nouislider
+   * https://refreshless.com/nouislider/slider-options/
+   */
+  config = {};
+
   /**
    * The current range of the filter
    */
@@ -78,6 +95,7 @@ export class SearchRangeFilterComponent extends SearchFacetFilterComponent imple
               protected filterService: SearchFilterService,
               protected router: Router,
               protected rdbs: RemoteDataBuildService,
+              private translateService: TranslateService,
               @Inject(SEARCH_CONFIG_SERVICE) public searchConfigService: SearchConfigurationService,
               @Inject(IN_PLACE_SEARCH) public inPlaceSearch: boolean,
               @Inject(FILTER_CONFIG) public filterConfig: SearchFilterConfig,
@@ -96,6 +114,8 @@ export class SearchRangeFilterComponent extends SearchFacetFilterComponent imple
     super.ngOnInit();
     this.min = yearFromString(this.filterConfig.minValue) || this.min;
     this.max = yearFromString(this.filterConfig.maxValue) || this.max;
+    this.minLabel = this.translateService.instant('search.filters.filter.' + this.filterConfig.name + '.min.placeholder');
+    this.maxLabel = this.translateService.instant('search.filters.filter.' + this.filterConfig.name + '.max.placeholder');
     const iniMin = this.route.getQueryParameterValue(this.filterConfig.paramName + RANGE_FILTER_MIN_SUFFIX).pipe(startWith(undefined));
     const iniMax = this.route.getQueryParameterValue(this.filterConfig.paramName + RANGE_FILTER_MAX_SUFFIX).pipe(startWith(undefined));
     this.sub = observableCombineLatest(iniMin, iniMax).pipe(
@@ -105,6 +125,15 @@ export class SearchRangeFilterComponent extends SearchFacetFilterComponent imple
         return [minimum, maximum];
       })
     ).subscribe((minmax) => this.range = minmax);
+
+    // Default/base config for nouislider
+    this.config = {
+      // Ensure draggable handles have labels
+      handleAttributes: [
+        { 'aria-label': this.minLabel },
+        { 'aria-label': this.maxLabel },
+      ],
+    };
   }
 
   /**