fix(common): don't generate srcset if noopImageLoader is used (#47804)

Do not generate a srcset if the loader being used is the default noopImageLoader. This loader does not take width into account, so it does not make sense to use it with srcsets.

PR Close #47804

Author: atcastle

packages/common/src/directives/ng_optimized_image/ng_optimized_image.ts

@@ -418,7 +418,8 @@ export class NgOptimizedImage implements OnInit, OnChanges, OnDestroy {
 
     if (this.ngSrcset) {
       rewrittenSrcset = this.getRewrittenSrcset();
-    } else if (!this._disableOptimizedSrcset && !this.srcset) {
+    } else if (
+        !this._disableOptimizedSrcset && !this.srcset && this.imageLoader !== noopImageLoader) {
       rewrittenSrcset = this.getAutomaticSrcset();
     }
 

packages/common/test/directives/ng_optimized_image_spec.ts

@@ -1401,6 +1401,20 @@ describe('Image directive', () => {
         return `${IMG_BASE_URL}/${config.src}${width}`;
       };
 
+      it('should not generate a srcset if the default noop loader is used', () => {
+        setupTestingModule({noLoader: true});
+
+        const template = `
+          <img ngSrc="img" width="100" height="50" sizes="100vw">
+        `;
+        const fixture = createTestComponent(template);
+        fixture.detectChanges();
+
+        const nativeElement = fixture.nativeElement as HTMLElement;
+        const img = nativeElement.querySelector('img')!;
+        expect(img.getAttribute('srcset')).toBeNull();
+      });
+
       it('should add a responsive srcset to the img element if sizes attribute exists', () => {
         setupTestingModule({imageLoader});
 
@@ -1538,6 +1552,7 @@ class TestComponent {
 function setupTestingModule(config?: {
   imageConfig?: ImageConfig,
   imageLoader?: ImageLoader,
+  noLoader?: boolean,
   extraProviders?: Provider[],
   component?: Type<unknown>
 }) {
@@ -1548,8 +1563,8 @@ function setupTestingModule(config?: {
   const loader = config?.imageLoader || defaultLoader;
   const extraProviders = config?.extraProviders || [];
   const providers: Provider[] = [
-    {provide: DOCUMENT, useValue: window.document}, {provide: IMAGE_LOADER, useValue: loader},
-    ...extraProviders
+    {provide: DOCUMENT, useValue: window.document},
+    ...(config?.noLoader ? [] : [{provide: IMAGE_LOADER, useValue: loader}]), ...extraProviders
   ];
   if (config?.imageConfig) {
     providers.push({provide: IMAGE_CONFIG, useValue: config.imageConfig});