From ee0786b20fbe918992cac1feae69ea425ff1f0ce Mon Sep 17 00:00:00 2001
From: Andrew Seguin <andrewjs@google.com>
Date: Wed, 16 Apr 2025 05:11:44 -0600
Subject: [PATCH]  fix(material/select): remove value from aria-labelledby

---
 src/material/paginator/paginator.spec.ts |  8 +++---
 src/material/select/select.spec.ts       | 31 +++---------------------
 src/material/select/select.ts            | 13 ++++++++--
 3 files changed, 17 insertions(+), 35 deletions(-)

diff --git a/src/material/paginator/paginator.spec.ts b/src/material/paginator/paginator.spec.ts
index b39927b72d15..9f141ef2b04a 100644
--- a/src/material/paginator/paginator.spec.ts
+++ b/src/material/paginator/paginator.spec.ts
@@ -106,11 +106,9 @@ describe('MatPaginator', () => {
       expect(getNextButton(fixture).getAttribute('aria-label')).toBe('Next page');
 
       const select = fixture.nativeElement.querySelector('.mat-mdc-select');
-      const selectLabelIds = select.getAttribute('aria-labelledby')?.split(/\s/g) as string[];
-      const selectLabelTexts = selectLabelIds?.map(labelId => {
-        return fixture.nativeElement.querySelector(`#${labelId}`)?.textContent?.trim();
-      });
-      expect(selectLabelTexts).toContain('Items per page:');
+      const selectLabelId = select.getAttribute('aria-labelledby').trim();
+      const selectLabelText = fixture.nativeElement.querySelector(`#${selectLabelId}`)?.textContent;
+      expect(selectLabelText).toContain('Items per page:');
     });
 
     it('should re-render when the i18n labels change', () => {
diff --git a/src/material/select/select.spec.ts b/src/material/select/select.spec.ts
index 30d9916a751a..038d723544ff 100644
--- a/src/material/select/select.spec.ts
+++ b/src/material/select/select.spec.ts
@@ -178,31 +178,17 @@ describe('MatSelect', () => {
           fixture.detectChanges();
 
           const labelId = fixture.nativeElement.querySelector('label').id;
-          const valueId = fixture.nativeElement.querySelector('.mat-mdc-select-value').id;
 
-          expect(select.getAttribute('aria-labelledby')).toBe(`${labelId} ${valueId} myLabelId`);
+          expect(select.getAttribute('aria-labelledby')).toBe(`${labelId} myLabelId`);
         });
 
-        it('should set aria-labelledby to the value and label IDs', () => {
+        it('should set aria-labelledby to the label ID', () => {
           fixture.detectChanges();
 
           const labelId = fixture.nativeElement.querySelector('label').id;
-          const valueId = fixture.nativeElement.querySelector('.mat-mdc-select-value').id;
-          expect(select.getAttribute('aria-labelledby')).toBe(`${labelId} ${valueId}`);
+          expect(select.getAttribute('aria-labelledby')).toBe(labelId);
         });
 
-        it('should trim the trigger aria-labelledby when there is no label', fakeAsync(() => {
-          fixture.componentInstance.hasLabel = false;
-          fixture.changeDetectorRef.markForCheck();
-          fixture.detectChanges();
-          flush();
-          fixture.detectChanges();
-
-          // Note that we assert that there are no spaces around the value.
-          const valueId = fixture.nativeElement.querySelector('.mat-mdc-select-value').id;
-          expect(select.getAttribute('aria-labelledby')).toBe(`${valueId}`);
-        }));
-
         it('should set the tabindex of the select to 0 by default', () => {
           expect(select.getAttribute('tabindex')).toEqual('0');
         });
@@ -297,17 +283,6 @@ describe('MatSelect', () => {
           expect(select.getAttribute('tabindex')).toEqual('0');
         });
 
-        it('should set `aria-labelledby` to the value ID if there is no form field', () => {
-          fixture.destroy();
-
-          const labelFixture = TestBed.createComponent(SelectWithChangeEvent);
-          labelFixture.detectChanges();
-          select = labelFixture.debugElement.query(By.css('mat-select'))!.nativeElement;
-          const valueId = labelFixture.nativeElement.querySelector('.mat-mdc-select-value').id;
-
-          expect(select.getAttribute('aria-labelledby')?.trim()).toBe(valueId);
-        });
-
         it('should select options via the UP/DOWN arrow keys on a closed select', fakeAsync(() => {
           const formControl = fixture.componentInstance.control;
           const options = fixture.componentInstance.options.toArray();
diff --git a/src/material/select/select.ts b/src/material/select/select.ts
index 005312acbe1b..005a466f5b2b 100644
--- a/src/material/select/select.ts
+++ b/src/material/select/select.ts
@@ -1439,13 +1439,22 @@ export class MatSelect
       return null;
     }
 
-    const labelId = this._parentFormField?.getLabelId();
-    let value = (labelId ? labelId + ' ' : '') + this._valueId;
+    let value = this._parentFormField?.getLabelId() || '';
 
     if (this.ariaLabelledby) {
       value += ' ' + this.ariaLabelledby;
     }
 
+    // The value should not be used for the trigger's aria-labelledby,
+    // but this currently "breaks" accessibility tests since they complain
+    // there is no aria-labelledby. This is because they are not setting an
+    // appropriate label on the form field or select.
+    // TODO: remove this conditional after fixing clients by ensuring their
+    // selects have a label applied.
+    if (!value) {
+      value = this._valueId;
+    }
+
     return value;
   }