ng_optimized_image_spec.ts

/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {CommonModule, DOCUMENT} from '@angular/common';
import {RuntimeErrorCode} from '@angular/common/src/errors';
import {PLATFORM_SERVER_ID} from '@angular/common/src/platform_id';
import {Component, PLATFORM_ID, Provider, Type} from '@angular/core';
import {ComponentFixture, TestBed} from '@angular/core/testing';
import {expect} from '@angular/platform-browser/testing/src/matchers';
import {withHead} from '@angular/private/testing';

import {PRELOADED_IMAGES} from '../..//src/directives/ng_optimized_image/tokens';
import {createImageLoader, IMAGE_LOADER, ImageLoader, ImageLoaderConfig} from '../../src/directives/ng_optimized_image/image_loaders/image_loader';
import {ABSOLUTE_SRCSET_DENSITY_CAP, assertValidNgSrcset, IMAGE_CONFIG, ImageConfig, NgOptimizedImage, RECOMMENDED_SRCSET_DENSITY_CAP} from '../../src/directives/ng_optimized_image/ng_optimized_image';
import {PRECONNECT_CHECK_BLOCKLIST} from '../../src/directives/ng_optimized_image/preconnect_link_checker';

describe('Image directive', () => {
  describe('preload <link> element on a server', () => {
    it('should create `<link>` element when the image priority attr is true', () => {
      // Only run this test in a browser since the Node-based DOM mocks don't
      // allow to override `HTMLImageElement.prototype.setAttribute` easily.
      if (!isBrowser) return;

      const src = 'preload1/img.png';

      setupTestingModule({
        extraProviders: [
          {provide: PLATFORM_ID, useValue: PLATFORM_SERVER_ID}, {
            provide: IMAGE_LOADER,
            useValue: (config: ImageLoaderConfig) => config.width ?
                `https://angular.io/${config.src}?width=${config.width}` :
                `https://angular.io/${config.src}`
          }
        ]
      });

      const template =
          `<img ngSrc="${src}" width="150" height="50" priority sizes="10vw" ngSrcset="100w">`;
      TestBed.overrideComponent(TestComponent, {set: {template: template}});

      const _document = TestBed.inject(DOCUMENT);
      const _window = _document.defaultView!;
      const setAttributeSpy =
          spyOn(_window.HTMLLinkElement.prototype, 'setAttribute').and.callThrough();

      const fixture = TestBed.createComponent(TestComponent);
      fixture.detectChanges();

      const head = _document.head;

      const rewrittenSrc = `https://angular.io/${src}`;

      const preloadLink = head.querySelector(`link[href="${rewrittenSrc}"]`);

      expect(preloadLink).toBeTruthy();

      const [name, value] = setAttributeSpy.calls.argsFor(0);

      expect(name).toEqual('as');
      expect(value).toEqual('image');

      expect(preloadLink!.getAttribute('rel')).toEqual('preload');
      expect(preloadLink!.getAttribute('as')).toEqual('image');
      expect(preloadLink!.getAttribute('imagesizes')).toEqual('10vw');
      expect(preloadLink!.getAttribute('imagesrcset')).toEqual(`${rewrittenSrc}?width=100 100w`);

      preloadLink!.remove();
    });

    it('should not create a preload `<link>` element when src is already preloaded.', () => {
      // Only run this test in a browser since the Node-based DOM mocks don't
      // allow to override `HTMLImageElement.prototype.setAttribute` easily.
      if (!isBrowser) return;

      const src = `preload2/img.png`;

      const rewrittenSrc = `https://angular.io/${src}`;

      setupTestingModule({
        extraProviders: [
          {provide: PLATFORM_ID, useValue: PLATFORM_SERVER_ID}, {
            provide: IMAGE_LOADER,
            useValue: (config: ImageLoaderConfig) => `https://angular.io/${config.src}`
          }
        ]
      });

      const template = `<img ngSrc="${src}" width="150" height="50" priority><img ngSrc="${
          src}" width="150" height="50" priority>`;
      TestBed.overrideComponent(TestComponent, {set: {template: template}});

      const _document = TestBed.inject(DOCUMENT);

      const fixture = TestBed.createComponent(TestComponent);
      fixture.detectChanges();

      const head = _document.head;

      const preloadImages = TestBed.inject(PRELOADED_IMAGES);

      expect(preloadImages.has(rewrittenSrc)).toBeTruthy();

      const preloadLinks = head.querySelectorAll(`link[href="${rewrittenSrc}"]`);

      expect(preloadLinks.length).toEqual(1);

      preloadLinks[0]!.remove();
    });

    it('should error when the number of preloaded images is larger than the limit', () => {
      // Only run this test in a browser since the Node-based DOM mocks don't
      // allow to override `HTMLImageElement.prototype.setAttribute` easily.
      if (!isBrowser) return;

      setupTestingModule({
        extraProviders: [
          {provide: PLATFORM_ID, useValue: PLATFORM_SERVER_ID}, {
            provide: IMAGE_LOADER,
            useValue: (config: ImageLoaderConfig) => `https://angular.io/${config.src}`
          }
        ]
      });

      const template = `
                <img ngSrc="preloaderror2/img.png" width="150" height="50" priority>
                <img ngSrc="preloaderror3/img.png" width="150" height="50" priority>
                <img ngSrc="preloaderro4/img.png" width="150" height="50" priority>
                <img ngSrc="preloaderror5/img.png" width="150" height="50" priority>
                <img ngSrc="preloaderror6/img.png" width="150" height="50" priority>
                <img ngSrc="preloaderror7/img.png" width="150" height="50" priority>
                <img ngSrc="preloaderror8/img.png" width="150" height="50" priority>
                <img ngSrc="preloaderror9/img.png" width="150" height="50" priority>
                <img ngSrc="preloaderror10/img.png" width="150" height="50" priority>
                `;

      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02961: The `NgOptimizedImage` directive has detected that more than 5 images were marked as priority. This might negatively affect an overall performance of the page. To fix this, remove the "priority" attribute from images with less priority.');
    });

    it('should not hit max preload limit when not on the server', () => {
      // Only run this test in a browser since the Node-based DOM mocks don't
      // allow to override `HTMLImageElement.prototype.setAttribute` easily.
      if (!isBrowser) return;

      setupTestingModule({
        extraProviders: [{
          provide: IMAGE_LOADER,
          useValue: (config: ImageLoaderConfig) => `https://angular.io/${config.src}`
        }]
      });

      const template = `
                <img ngSrc="preloadbrowser1/img.png" width="150" height="50" priority>
                <img ngSrc="preloadbrowser2/img.png" width="150" height="50" priority>
                <img ngSrc="preloadbrowser3/img.png" width="150" height="50" priority>
                <img ngSrc="preloadbrowser4/img.png" width="150" height="50" priority>
                <img ngSrc="preloadbrowser5/img.png" width="150" height="50" priority>
                <img ngSrc="preloadbrowser6/img.png" width="150" height="50" priority>
                <img ngSrc="preloadbrowser7/img.png" width="150" height="50" priority>
                <img ngSrc="preloadbrowser8/img.png" width="150" height="50" priority>
                <img ngSrc="preloadbrowser9/img.png" width="150" height="50" priority>
                `;

      TestBed.overrideComponent(TestComponent, {set: {template: template}});

      const _document = TestBed.inject(DOCUMENT);

      const fixture = TestBed.createComponent(TestComponent);
      fixture.detectChanges();

      const head = _document.head;

      const preloadImages = TestBed.inject(PRELOADED_IMAGES);

      const preloadLinks = head.querySelectorAll(`link[preload]`);

      expect(preloadImages.size).toEqual(0);
      expect(preloadLinks.length).toEqual(0);
    });
  });

  it('should set `loading` and `fetchpriority` attributes before `src`', () => {
    // Only run this test in a browser since the Node-based DOM mocks don't
    // allow to override `HTMLImageElement.prototype.setAttribute` easily.
    if (!isBrowser) return;

    setupTestingModule();

    const template = '<img ngSrc="path/img.png" width="150" height="50" priority>';
    TestBed.overrideComponent(TestComponent, {set: {template: template}});

    const _document = TestBed.inject(DOCUMENT);
    const _window = _document.defaultView!;
    const setAttributeSpy =
        spyOn(_window.HTMLImageElement.prototype, 'setAttribute').and.callThrough();

    const fixture = TestBed.createComponent(TestComponent);
    fixture.detectChanges();

    const nativeElement = fixture.nativeElement as HTMLElement;

    const img = nativeElement.querySelector('img')!;
    expect(img.getAttribute('loading')).toBe('eager');

    let _imgInstance = null;
    let _loadingAttrId = -1;
    let _fetchpriorityAttrId = -1;
    let _srcAttrId = -1;
    const count = setAttributeSpy.calls.count();
    for (let i = 0; i < count; i++) {
      if (!_imgInstance) {
        _imgInstance = setAttributeSpy.calls.thisFor(i);
      } else if (_imgInstance !== setAttributeSpy.calls.thisFor(i)) {
        // Verify that the <img> instance is the same during the test.
        fail('Unexpected instance of a second <img> instance present in a test.');
      }

      // Note: spy.calls.argsFor(i) returns args as an array: ['src', 'eager']
      const attrName = setAttributeSpy.calls.argsFor(i)[0];
      if (attrName == 'loading') _loadingAttrId = i;
      if (attrName == 'fetchpriority') _fetchpriorityAttrId = i;
      if (attrName == 'src') _srcAttrId = i;
    }
    // Verify that both `loading` and `fetchpriority` are set *before* `src`:
    expect(_loadingAttrId).toBeGreaterThan(-1);       // was actually set
    expect(_loadingAttrId).toBeLessThan(_srcAttrId);  // was set after `src`

    expect(_fetchpriorityAttrId).toBeGreaterThan(-1);       // was actually set
    expect(_fetchpriorityAttrId).toBeLessThan(_srcAttrId);  // was set after `src`
  });

  it('should always reflect the width/height attributes if bound', () => {
    setupTestingModule();

    const template = '<img ngSrc="path/img.png" [width]="width" [height]="height">';
    const fixture = createTestComponent(template);
    fixture.detectChanges();

    const nativeElement = fixture.nativeElement as HTMLElement;
    const img = nativeElement.querySelector('img')!;
    expect(img.getAttribute('width')).toBe('100');
    expect(img.getAttribute('height')).toBe('50');
  });

  describe('setup error handling', () => {
    it('should throw if both `src` and `ngSrc` are present', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" src="path/img2.png" width="100" height="50">';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02950: The NgOptimizedImage directive (activated on an <img> ' +
              'element with the `ngSrc="path/img.png"`) has detected that both ' +
              '`src` and `ngSrc` have been set. Supplying both of these attributes ' +
              'breaks lazy loading. The NgOptimizedImage directive sets `src` ' +
              'itself based on the value of `ngSrc`. To fix this, please remove ' +
              'the `src` attribute.');
    });

    it('should throw if both `ngSrcet` and `srcset` is present', () => {
      setupTestingModule();

      const template =
          '<img ngSrc="img-100.png" ngSrcset="100w, 200w" srcset="img-100.png 100w, img-200.png 200w" width="100" height="50">';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02951: The NgOptimizedImage directive (activated on an <img> ' +
              'element with the `ngSrc="img-100.png"`) has detected that both ' +
              '`srcset` and `ngSrcset` have been set. Supplying both of these ' +
              'attributes breaks lazy loading. ' +
              'The NgOptimizedImage directive sets `srcset` itself based ' +
              'on the value of `ngSrcset`. To fix this, please remove the `srcset` ' +
              'attribute.');
    });

    it('should throw if an old `rawSrc` is present', () => {
      setupTestingModule();

      const template = '<img rawSrc="path/img.png" src="path/img2.png" width="100" height="50">';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02952: The NgOptimizedImage directive has detected that the `rawSrc` ' +
              'attribute was used to activate the directive. Newer version of the directive uses ' +
              'the `ngSrc` attribute instead. Please replace `rawSrc` with `ngSrc` and ' +
              '`rawSrcset` with `ngSrcset` attributes in the template to enable image optimizations.');
    });

    it('should throw if `ngSrc` contains a Base64-encoded image (that starts with `data:`)', () => {
      setupTestingModule();

      expect(() => {
        const template = '<img ngSrc="' + ANGULAR_LOGO_BASE64 + '" width="50" height="50">';
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02952: The NgOptimizedImage directive has detected that `ngSrc` ' +
              'is a Base64-encoded string (data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDov...). ' +
              'NgOptimizedImage does not support Base64-encoded strings. ' +
              'To fix this, disable the NgOptimizedImage directive for this element ' +
              'by removing `ngSrc` and using a standard `src` attribute instead.');
    });

    it('should throw if `ngSrc` contains a `blob:` URL', (done) => {
      // Domino does not support canvas elements properly,
      // so run this test only in a browser.
      if (!isBrowser) {
        done();
        return;
      }

      const canvas = document.createElement('canvas');
      canvas.toBlob(function(blob) {
        const blobURL = URL.createObjectURL(blob!);

        setupTestingModule();

        // Note: use RegExp to partially match the error message, since the blob URL
        // is created dynamically, so it might be different for each invocation.
        const errorMessageRegExp =
            /NG02952: The NgOptimizedImage directive (.*?) has detected that `ngSrc` was set to a blob URL \(blob:/;
        expect(() => {
          const template = '<img ngSrc="' + blobURL + '" width="50" height="50">';
          const fixture = createTestComponent(template);
          fixture.detectChanges();
        }).toThrowError(errorMessageRegExp);
        done();
      });
    });

    it('should throw if `width` and `height` are not set', () => {
      setupTestingModule();

      const template = '<img ngSrc="img.png">';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02954: The NgOptimizedImage directive (activated on an <img> ' +
              'element with the `ngSrc="img.png"`) has detected that these ' +
              'required attributes are missing: "width", "height". Including "width" and ' +
              '"height" attributes will prevent image-related layout shifts. ' +
              'To fix this, include "width" and "height" attributes on the image tag.');
    });

    it('should throw if `width` is not set', () => {
      setupTestingModule();

      const template = '<img ngSrc="img.png" height="10">';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02954: The NgOptimizedImage directive (activated on an <img> ' +
              'element with the `ngSrc="img.png"`) has detected that these ' +
              'required attributes are missing: "width". Including "width" and ' +
              '"height" attributes will prevent image-related layout shifts. ' +
              'To fix this, include "width" and "height" attributes on the image tag.');
    });

    it('should throw if `width` is 0', () => {
      setupTestingModule();

      const template = '<img ngSrc="img.png" width="0" height="10">';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02952: The NgOptimizedImage directive (activated on an <img> ' +
              'element with the `ngSrc="img.png"`) has detected that `width` ' +
              'has an invalid value (`0`). To fix this, provide `width` as ' +
              'a number greater than 0.');
    });

    it('should throw if `width` has an invalid value', () => {
      setupTestingModule();

      const template = '<img ngSrc="img.png" width="10px" height="10">';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02952: The NgOptimizedImage directive (activated on an <img> ' +
              'element with the `ngSrc="img.png"`) has detected that `width` ' +
              'has an invalid value (`10px`). To fix this, provide `width` ' +
              'as a number greater than 0.');
    });

    it('should throw if `height` is not set', () => {
      setupTestingModule();

      const template = '<img ngSrc="img.png" width="10">';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02954: The NgOptimizedImage directive (activated on an <img> ' +
              'element with the `ngSrc="img.png"`) has detected that these required ' +
              'attributes are missing: "height". Including "width" and "height" ' +
              'attributes will prevent image-related layout shifts. ' +
              'To fix this, include "width" and "height" attributes on the image tag.');
    });

    it('should throw if `height` is 0', () => {
      setupTestingModule();

      const template = '<img ngSrc="img.png" width="10" height="0">';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02952: The NgOptimizedImage directive (activated on an <img> ' +
              'element with the `ngSrc="img.png"`) has detected that `height` ' +
              'has an invalid value (`0`). To fix this, provide `height` as a number ' +
              'greater than 0.');
    });

    it('should throw if `height` has an invalid value', () => {
      setupTestingModule();

      const template = '<img ngSrc="img.png" width="10" height="10%">';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02952: The NgOptimizedImage directive (activated on an <img> element ' +
              'with the `ngSrc="img.png"`) has detected that `height` has an invalid ' +
              'value (`10%`). To fix this, provide `height` as a number greater than 0.');
    });

    it('should throw if `ngSrc` value is not provided', () => {
      setupTestingModule();

      const template = '<img ngSrc>';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02952: The NgOptimizedImage directive (activated on an <img> ' +
              'element with the `ngSrc=""`) has detected that `ngSrc` has an ' +
              'invalid value (``). ' +
              'To fix this, change the value to a non-empty string.');
    });

    it('should throw if `ngSrc` value is set to an empty string', () => {
      setupTestingModule();

      const template = '<img ngSrc="  ">';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02952: The NgOptimizedImage directive (activated on an <img> element ' +
              'with the `ngSrc="  "`) has detected that `ngSrc` has an invalid value ' +
              '(`  `). To fix this, change the value to a non-empty string.');
    });

    describe('invalid `ngSrcset` values', () => {
      const mockDirectiveInstance = {ngSrc: 'img.png'} as NgOptimizedImage;

      it('should throw for empty ngSrcSet', () => {
        const imageLoader = (config: ImageLoaderConfig) => {
          const width = config.width ? `-${config.width}` : ``;
          return window.location.origin + `/path/${config.src}${width}.png`;
        };
        setupTestingModule({imageLoader});

        const template = `
            <img ngSrc="img" ngSrcset="" width="100" height="50">
          `;
        expect(() => {
          const fixture = createTestComponent(template);
          fixture.detectChanges();
        })
            .toThrowError(
                'NG02952: The NgOptimizedImage directive (activated on an <img> ' +
                'element with the `ngSrc="img"`) has detected that `ngSrcset` ' +
                'has an invalid value (``). ' +
                'To fix this, change the value to a non-empty string.');
      });

      it('should throw for invalid ngSrcSet', () => {
        const imageLoader = (config: ImageLoaderConfig) => {
          const width = config.width ? `-${config.width}` : ``;
          return window.location.origin + `/path/${config.src}${width}.png`;
        };
        setupTestingModule({imageLoader});

        const template = `
            <img ngSrc="img" ngSrcset="100q, 200q" width="100" height="50">
          `;
        expect(() => {
          const fixture = createTestComponent(template);
          fixture.detectChanges();
        })
            .toThrowError(
                'NG02952: The NgOptimizedImage directive (activated on an <img> element ' +
                'with the `ngSrc="img"`) has detected that `ngSrcset` has an invalid value ' +
                '(`100q, 200q`). To fix this, supply `ngSrcset` using a comma-separated list ' +
                'of one or more width descriptors (e.g. "100w, 200w") or density descriptors ' +
                '(e.g. "1x, 2x").');
      });

      it('should throw if ngSrcset exceeds the density cap', () => {
        const imageLoader = (config: ImageLoaderConfig) => {
          const width = config.width ? `-${config.width}` : ``;
          return window.location.origin + `/path/${config.src}${width}.png`;
        };
        setupTestingModule({imageLoader});

        const template = `
            <img ngSrc="img" ngSrcset="1x, 2x, 3x, 4x, 5x" width="100" height="50">
          `;
        expect(() => {
          const fixture = createTestComponent(template);
          fixture.detectChanges();
        })
            .toThrowError(
                `NG0${
                    RuntimeErrorCode
                        .INVALID_INPUT}: The NgOptimizedImage directive (activated on an <img> element with the \`ngSrc="img"\`) ` +
                `has detected that the \`ngSrcset\` contains an unsupported image density:` +
                `\`1x, 2x, 3x, 4x, 5x\`. NgOptimizedImage generally recommends a max image density of ` +
                `${RECOMMENDED_SRCSET_DENSITY_CAP}x but supports image densities up to ` +
                `${ABSOLUTE_SRCSET_DENSITY_CAP}x. The human eye cannot distinguish between image densities ` +
                `greater than ${
                    RECOMMENDED_SRCSET_DENSITY_CAP}x - which makes them unnecessary for ` +
                `most use cases. Images that will be pinch-zoomed are typically the primary use case for ` +
                `${ABSOLUTE_SRCSET_DENSITY_CAP}x images. Please remove the high density descriptor and try again.`);
      });


      it('should throw if ngSrcset exceeds the density cap with multiple digits', () => {
        const imageLoader = (config: ImageLoaderConfig) => {
          const width = config.width ? `-${config.width}` : ``;
          return window.location.origin + `/path/${config.src}${width}.png`;
        };
        setupTestingModule({imageLoader});

        const template = `
            <img ngSrc="img" ngSrcset="1x, 200x" width="100" height="50">
          `;
        expect(() => {
          const fixture = createTestComponent(template);
          fixture.detectChanges();
        })
            .toThrowError(
                `NG0${
                    RuntimeErrorCode
                        .INVALID_INPUT}: The NgOptimizedImage directive (activated on an <img> element with the \`ngSrc="img"\`) ` +
                `has detected that the \`ngSrcset\` contains an unsupported image density:` +
                `\`1x, 200x\`. NgOptimizedImage generally recommends a max image density of ` +
                `${RECOMMENDED_SRCSET_DENSITY_CAP}x but supports image densities up to ` +
                `${ABSOLUTE_SRCSET_DENSITY_CAP}x. The human eye cannot distinguish between image densities ` +
                `greater than ${
                    RECOMMENDED_SRCSET_DENSITY_CAP}x - which makes them unnecessary for ` +
                `most use cases. Images that will be pinch-zoomed are typically the primary use case for ` +
                `${ABSOLUTE_SRCSET_DENSITY_CAP}x images. Please remove the high density descriptor and try again.`);
      });

      it('should throw if width srcset is missing a comma', () => {
        expect(() => {
          assertValidNgSrcset(mockDirectiveInstance, '100w 200w');
        }).toThrowError();
      });

      it('should throw if density srcset is missing a comma', () => {
        expect(() => {
          assertValidNgSrcset(mockDirectiveInstance, '1x 2x');
        }).toThrowError();
      });

      it('should throw if density srcset has too many digits', () => {
        expect(() => {
          assertValidNgSrcset(mockDirectiveInstance, '100x, 2x');
        }).toThrowError();
      });

      it('should throw if width srcset includes a file name', () => {
        expect(() => {
          assertValidNgSrcset(mockDirectiveInstance, 'a.png 100w, b.png 200w');
        }).toThrowError();
      });

      it('should throw if density srcset includes a file name', () => {
        expect(() => {
          assertValidNgSrcset(mockDirectiveInstance, 'a.png 1x, b.png 2x');
        }).toThrowError();
      });

      it('should throw if srcset starts with a letter', () => {
        expect(() => {
          assertValidNgSrcset(mockDirectiveInstance, 'a100w, 200w');
        }).toThrowError();
      });

      it('should throw if srcset starts with another non-digit', () => {
        expect(() => {
          assertValidNgSrcset(mockDirectiveInstance, '--100w, 200w');
        }).toThrowError();
      });

      it('should throw if first descriptor in srcset is junk', () => {
        expect(() => {
          assertValidNgSrcset(mockDirectiveInstance, 'foo, 1x');
        }).toThrowError();
      });

      it('should throw if later descriptors in srcset are junk', () => {
        expect(() => {
          assertValidNgSrcset(mockDirectiveInstance, '100w, foo');
        }).toThrowError();
      });

      it('should throw if srcset has a density descriptor after a width descriptor', () => {
        expect(() => {
          assertValidNgSrcset(mockDirectiveInstance, '100w, 1x');
        }).toThrowError();
      });

      it('should throw if srcset has a width descriptor after a density descriptor', () => {
        expect(() => {
          assertValidNgSrcset(mockDirectiveInstance, '1x, 200w');
        }).toThrowError();
      });
    });

    const inputs = [
      ['ngSrc', 'new-img.png'],  //
      ['width', 10],             //
      ['height', 20],            //
      ['priority', true]
    ];
    inputs.forEach(([inputName, value]) => {
      it(`should throw if an input changed after directive initialized the input`, () => {
        setupTestingModule();

        const template =
            '<img [ngSrc]="ngSrc" [width]="width" [height]="height" [priority]="priority">';
        // Initial render
        const fixture = createTestComponent(template);
        fixture.detectChanges();

        expect(() => {
          // Update input (expect to throw)
          (fixture.componentInstance as unknown as {[key: string]: unknown})[inputName as string] =
              value;
          fixture.detectChanges();
        })
            .toThrowError(
                'NG02953: The NgOptimizedImage directive (activated on an <img> element ' +
                `with the \`ngSrc="img.png"\`) has detected that \`${inputName}\` was updated ` +
                'after initialization. The NgOptimizedImage directive will not react ' +
                `to this input change. To fix this, switch \`${inputName}\` a static value or ` +
                'wrap the image element in an *ngIf that is gated on the necessary value.');
      });
    });
  });

  describe('lazy loading', () => {
    it('should eagerly load priority images', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" width="150" height="50" priority>';
      const fixture = createTestComponent(template);
      fixture.detectChanges();

      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.getAttribute('loading')).toBe('eager');
    });

    it('should lazily load non-priority images', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" width="150" height="50">';
      const fixture = createTestComponent(template);
      fixture.detectChanges();

      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.getAttribute('loading')).toBe('lazy');
    });
  });

  describe('loading attribute', () => {
    it('should override the default loading behavior for non-priority images', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" width="150" height="50" loading="eager">';
      const fixture = createTestComponent(template);
      fixture.detectChanges();

      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.getAttribute('loading')).toBe('eager');
    });

    it('should throw if used with priority images', () => {
      setupTestingModule();

      const template =
          '<img ngSrc="path/img.png" width="150" height="50" loading="eager" priority>';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02952: The NgOptimizedImage directive (activated on an <img> element ' +
              'with the `ngSrc="path/img.png"`) has detected that the `loading` attribute ' +
              'was used on an image that was marked "priority". Setting `loading` on priority ' +
              'images is not allowed because these images will always be eagerly loaded. ' +
              'To fix this, remove the “loading” attribute from the priority image.');
    });

    it('should support setting loading priority to "auto"', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" width="150" height="50" loading="auto">';
      const fixture = createTestComponent(template);
      fixture.detectChanges();

      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.getAttribute('loading')).toBe('auto');
    });

    it('should throw for invalid loading inputs', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" width="150" height="150" loading="fast">';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02952: The NgOptimizedImage directive (activated on an <img> element ' +
              'with the `ngSrc="path/img.png"`) has detected that the `loading` attribute ' +
              'has an invalid value (`fast`). To fix this, provide a valid value ("lazy", ' +
              '"eager", or "auto").');
    });
  });

  describe('fetch priority', () => {
    it('should be "high" for priority images', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" width="150" height="50" priority>';
      const fixture = createTestComponent(template);
      fixture.detectChanges();

      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.getAttribute('fetchpriority')).toBe('high');
    });

    it('should be "auto" for non-priority images', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" width="150" height="50">';
      const fixture = createTestComponent(template);
      fixture.detectChanges();

      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.getAttribute('fetchpriority')).toBe('auto');
    });
  });

  describe('fill mode', () => {
    it('should allow unsized images in fill mode', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" fill>';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      }).not.toThrow();
    });
    it('should throw if width is provided for fill mode image', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" width="500" fill>';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02952: The NgOptimizedImage directive (activated on an <img> element with the ' +
              '`ngSrc="path/img.png"`) has detected that the attributes `height` and/or `width` ' +
              'are present along with the `fill` attribute. Because `fill` mode causes an image ' +
              'to fill its containing element, the size attributes have no effect and should be removed.');
    });
    it('should throw if height is provided for fill mode image', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" height="500" fill>';
      expect(() => {
        const fixture = createTestComponent(template);
        fixture.detectChanges();
      })
          .toThrowError(
              'NG02952: The NgOptimizedImage directive (activated on an <img> element with the ' +
              '`ngSrc="path/img.png"`) has detected that the attributes `height` and/or `width` ' +
              'are present along with the `fill` attribute. Because `fill` mode causes an image ' +
              'to fill its containing element, the size attributes have no effect and should be removed.');
    });
    it('should apply appropriate styles in fill mode', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" fill>';

      const fixture = createTestComponent(template);
      fixture.detectChanges();
      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.getAttribute('style')?.replace(/\s/g, ''))
          .toBe('position:absolute;width:100%;height:100%;inset:0px;');
    });
    it('should augment existing styles in fill mode', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" style="border-radius: 5px; padding: 10px" fill>';

      const fixture = createTestComponent(template);
      fixture.detectChanges();
      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.getAttribute('style')?.replace(/\s/g, ''))
          .toBe(
              'border-radius:5px;padding:10px;position:absolute;width:100%;height:100%;inset:0px;');
    });
    it('should not add fill styles if not in fill mode', () => {
      setupTestingModule();

      const template =
          '<img ngSrc="path/img.png" width="400" height="300" style="position: relative; border-radius: 5px">';

      const fixture = createTestComponent(template);
      fixture.detectChanges();
      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.getAttribute('style')?.replace(/\s/g, ''))
          .toBe('position:relative;border-radius:5px;');
    });
    it('should add default sizes value in fill mode', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" fill>';

      const fixture = createTestComponent(template);
      fixture.detectChanges();
      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.getAttribute('sizes')).toBe('100vw');
    });
    it('should not overwrite sizes value in fill mode', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" sizes="50vw" fill>';

      const fixture = createTestComponent(template);
      fixture.detectChanges();
      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.getAttribute('sizes')).toBe('50vw');
    });
    it('should cause responsive srcset to be generated in fill mode', () => {
      setupTestingModule();

      const template = '<img ngSrc="path/img.png" fill>';

      const fixture = createTestComponent(template);
      fixture.detectChanges();
      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.getAttribute('srcset'))
          .toBe(
              `${IMG_BASE_URL}/path/img.png 640w, ${IMG_BASE_URL}/path/img.png 750w, ${
                  IMG_BASE_URL}/path/img.png 828w, ` +
              `${IMG_BASE_URL}/path/img.png 1080w, ${IMG_BASE_URL}/path/img.png 1200w, ${
                  IMG_BASE_URL}/path/img.png 1920w, ` +
              `${IMG_BASE_URL}/path/img.png 2048w, ${IMG_BASE_URL}/path/img.png 3840w`);
    });
  });

  describe('preconnect detector', () => {
    const imageLoader = () => {
      // We need something different from the `localhost` (as we don't want to produce
      // a preconnect warning for local environments).
      return 'https://angular.io/assets/images/logos/angular/angular.svg';
    };

    it('should log a warning if there is no preconnect link for a priority image',
       withHead('', () => {
         setupTestingModule({imageLoader});

         const consoleWarnSpy = spyOn(console, 'warn');
         const template = '<img ngSrc="a.png" width="100" height="50" priority>';
         const fixture = createTestComponent(template);
         fixture.detectChanges();

         expect(consoleWarnSpy.calls.count()).toBe(1);
         expect(consoleWarnSpy.calls.argsFor(0)[0])
             .toBe(
                 'NG02956: The NgOptimizedImage directive (activated on an <img> element ' +
                 'with the `ngSrc="a.png"`) has detected that there is no preconnect tag ' +
                 'present for this image. Preconnecting to the origin(s) that serve ' +
                 'priority images ensures that these images are delivered as soon as ' +
                 'possible. To fix this, please add the following element into the <head> ' +
                 'of the document:' +
                 '\n  <link rel="preconnect" href="https://angular.io">');
       }));

    it('should not log a warning if there is no preconnect link, but the image is not set as a priority',
       withHead('', () => {
         setupTestingModule({imageLoader});

         const consoleWarnSpy = spyOn(console, 'warn');
         const template = '<img ngSrc="a.png" width="100" height="50">';
         const fixture = createTestComponent(template);
         fixture.detectChanges();

         // Expect no warnings in the console.
         expect(consoleWarnSpy.calls.count()).toBe(0);
       }));

    it('should log a warning if there is a preconnect, but it doesn\'t match the priority image',
       withHead('<link rel="preconnect" href="http://angular.io">', () => {
         setupTestingModule({imageLoader});

         const consoleWarnSpy = spyOn(console, 'warn');
         const template = '<img ngSrc="a.png" width="100" height="50" priority>';
         const fixture = createTestComponent(template);
         fixture.detectChanges();

         expect(consoleWarnSpy.calls.count()).toBe(1);
         expect(consoleWarnSpy.calls.argsFor(0)[0])
             .toBe(
                 'NG02956: The NgOptimizedImage directive (activated on an <img> element ' +
                 'with the `ngSrc="a.png"`) has detected that there is no preconnect tag ' +
                 'present for this image. Preconnecting to the origin(s) that serve priority ' +
                 'images ensures that these images are delivered as soon as possible. ' +
                 'To fix this, please add the following element into the <head> of the document:' +
                 '\n  <link rel="preconnect" href="https://angular.io">');
       }));

    it('should log a warning if there is no matching preconnect link for a priority image, but there is a preload tag',
       withHead(
           '<link rel="preload" href="https://angular.io/assets/images/logos/angular/angular.svg" as="image">',
           () => {
             setupTestingModule({imageLoader});

             const consoleWarnSpy = spyOn(console, 'warn');
             const template = '<img ngSrc="a.png" width="100" height="50" priority>';
             const fixture = createTestComponent(template);
             fixture.detectChanges();

             expect(consoleWarnSpy.calls.count()).toBe(1);
             expect(consoleWarnSpy.calls.argsFor(0)[0])
                 .toBe(
                     'NG02956: The NgOptimizedImage directive (activated on an <img> element ' +
                     'with the `ngSrc="a.png"`) has detected that there is no preconnect tag ' +
                     'present for this image. Preconnecting to the origin(s) that serve priority ' +
                     'images ensures that these images are delivered as soon as possible. ' +
                     'To fix this, please add the following element into the <head> of the document:' +
                     '\n  <link rel="preconnect" href="https://angular.io">');
           }));

    it('should not log a warning if there is a matching preconnect link for a priority image (with an extra `/` at the end)',
       withHead('<link rel="preconnect" href="https://angular.io/">', () => {
         setupTestingModule({imageLoader});

         const consoleWarnSpy = spyOn(console, 'warn');
         const template = '<img ngSrc="a.png" width="100" height="50" priority>';
         const fixture = createTestComponent(template);
         fixture.detectChanges();

         // Expect no warnings in the console.
         expect(consoleWarnSpy.calls.count()).toBe(0);
       }));

    ['localhost', '127.0.0.1', '0.0.0.0'].forEach(blocklistedHostname => {
      it(`should not log a warning if an origin domain is blocklisted ` +
             `(checking ${blocklistedHostname})`,
         withHead('', () => {
           const imageLoader = () => {
             return `http://${blocklistedHostname}/a.png`;
           };
           setupTestingModule({imageLoader});

           const consoleWarnSpy = spyOn(console, 'warn');
           const template = '<img ngSrc="a.png" width="100" height="50" priority>';
           const fixture = createTestComponent(template);
           fixture.detectChanges();

           // Expect no warnings in the console.
           expect(consoleWarnSpy.calls.count()).toBe(0);
         }));
    });

    describe('PRECONNECT_CHECK_BLOCKLIST token', () => {
      it(`should allow passing host names`, withHead('', () => {
           const providers = [{provide: PRECONNECT_CHECK_BLOCKLIST, useValue: 'angular.io'}];
           setupTestingModule({imageLoader, extraProviders: providers});

           const consoleWarnSpy = spyOn(console, 'warn');
           const template = '<img ngSrc="a.png" width="100" height="50" priority>';
           const fixture = createTestComponent(template);
           fixture.detectChanges();

           // Expect no warnings in the console.
           expect(consoleWarnSpy.calls.count()).toBe(0);
         }));

      it(`should allow passing origins`, withHead('', () => {
           const providers =
               [{provide: PRECONNECT_CHECK_BLOCKLIST, useValue: 'https://angular.io'}];
           setupTestingModule({imageLoader, extraProviders: providers});

           const consoleWarnSpy = spyOn(console, 'warn');
           const template = '<img ngSrc="a.png" width="100" height="50" priority>';
           const fixture = createTestComponent(template);
           fixture.detectChanges();

           // Expect no warnings in the console.
           expect(consoleWarnSpy.calls.count()).toBe(0);
         }));

      it(`should allow passing arrays of host names`, withHead('', () => {
           const providers =
               [{provide: PRECONNECT_CHECK_BLOCKLIST, useValue: ['https://angular.io']}];
           setupTestingModule({imageLoader, extraProviders: providers});

           const consoleWarnSpy = spyOn(console, 'warn');
           const template = '<img ngSrc="a.png" width="100" height="50" priority>';
           const fixture = createTestComponent(template);
           fixture.detectChanges();

           // Expect no warnings in the console.
           expect(consoleWarnSpy.calls.count()).toBe(0);
         }));

      it(`should allow passing nested arrays of host names`, withHead('', () => {
           const providers =
               [{provide: PRECONNECT_CHECK_BLOCKLIST, useValue: [['https://angular.io']]}];
           setupTestingModule({imageLoader, extraProviders: providers});

           const consoleWarnSpy = spyOn(console, 'warn');
           const template = '<img ngSrc="a.png" width="100" height="50" priority>';
           const fixture = createTestComponent(template);
           fixture.detectChanges();

           // Expect no warnings in the console.
           expect(consoleWarnSpy.calls.count()).toBe(0);
         }));
    });
  });

  describe('loaders', () => {
    it('should set `src` to match `ngSrc` if image loader is not provided', () => {
      setupTestingModule();

      const template = `<img ngSrc="${IMG_BASE_URL}/img.png" width="100" height="50">`;
      const fixture = createTestComponent(template);
      fixture.detectChanges();

      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.src).toBe(`${IMG_BASE_URL}/img.png`);
    });

    it('should set `src` using the image loader provided via the `IMAGE_LOADER` token to compose src URL',
       () => {
         const imageLoader = (config: ImageLoaderConfig) => `${IMG_BASE_URL}/${config.src}`;
         setupTestingModule({imageLoader});

         const template = `
         <img ngSrc="img.png" width="150" height="50">
         <img ngSrc="img-2.png" width="150" height="50">
       `;
         const fixture = createTestComponent(template);
         fixture.detectChanges();

         const nativeElement = fixture.nativeElement as HTMLElement;
         const imgs = nativeElement.querySelectorAll('img')!;
         expect(imgs[0].src.trim()).toBe(`${IMG_BASE_URL}/img.png`);
         expect(imgs[1].src.trim()).toBe(`${IMG_BASE_URL}/img-2.png`);
       });

    it('should pass absolute URLs defined in the `ngSrc` to custom image loaders provided via the `IMAGE_LOADER` token',
       () => {
         const imageLoader = (config: ImageLoaderConfig) => `${config.src}?rewritten=true`;
         setupTestingModule({imageLoader});

         const template = `
            <img ngSrc="${IMG_BASE_URL}/img.png" width="150" height="50">
          `;
         const fixture = createTestComponent(template);
         fixture.detectChanges();

         const nativeElement = fixture.nativeElement as HTMLElement;
         const imgs = nativeElement.querySelectorAll('img')!;
         expect(imgs[0].src.trim()).toBe(`${IMG_BASE_URL}/img.png?rewritten=true`);
       });

    it('should set `src` to an image URL that does not include a default width parameter', () => {
      const imageLoader = (config: ImageLoaderConfig) => {
        const widthStr = config.width ? `?w=${config.width}` : ``;
        return `${IMG_BASE_URL}/${config.src}${widthStr}`;
      };
      setupTestingModule({imageLoader});

      const template = '<img ngSrc="img.png" width="150" height="50">';
      const fixture = createTestComponent(template);
      fixture.detectChanges();

      const nativeElement = fixture.nativeElement as HTMLElement;
      const img = nativeElement.querySelector('img')!;
      expect(img.src).toBe(`${IMG_BASE_URL}/img.png`);
    });

    it(`should allow providing image loaders via Component providers`, withHead('', () => {
         const createImgUrl = (path: string, config: ImageLoaderConfig) => `${path}/${config.src}`;
         const loaderWithPath = createImageLoader(createImgUrl);

         @Component({
           selector: 'test-cmp',
           template: '<img ngSrc="a.png" width="100" height="50" priority>',
           providers: [loaderWithPath('https://component.io')]
         })
         class TestComponent {
         }

         setupTestingModule(
             {component: TestComponent, extraProviders: [loaderWithPath('https://default.io')]});

         const fixture = TestBed.createComponent(TestComponent);
         fixture.detectChanges();

         const defaultLoader = TestBed.inject(IMAGE_LOADER);
         const nativeElement = fixture.nativeElement as HTMLElement;
         const img = nativeElement.querySelector('img')!;

         expect(defaultLoader({src: 'a.png'})).toBe('https://default.io/a.png');
         expect(img.src).toBe('https://component.io/a.png');
       }));

    describe('`ngSrcset` values', () => {
      let imageLoader!: ImageLoader;

      beforeEach(() => {
        imageLoader = (config: ImageLoaderConfig) => {
          const width = config.width ? `?w=${config.width}` : ``;
          return `${IMG_BASE_URL}/${config.src}${width}`;
        };
      });

      it('should set the `srcset` using the `ngSrcset` value with width descriptors', () => {
        setupTestingModule({imageLoader});

        const template = `
           <img ngSrc="img.png" ngSrcset="100w, 200w" width="100" height="50">
         `;
        const fixture = createTestComponent(template);
        fixture.detectChanges();

        const nativeElement = fixture.nativeElement as HTMLElement;
        const img = nativeElement.querySelector('img')!;
        expect(img.src).toBe(`${IMG_BASE_URL}/img.png`);
        expect(img.srcset)
            .toBe(`${IMG_BASE_URL}/img.png?w=100 100w, ${IMG_BASE_URL}/img.png?w=200 200w`);
      });

      it('should set the `srcset` using the `ngSrcset` value with density descriptors', () => {
        setupTestingModule({imageLoader});

        const template = `
           <img ngSrc="img.png" ngSrcset="1x, 2x" width="100" height="50">
         `;
        const fixture = createTestComponent(template);
        fixture.detectChanges();

        const nativeElement = fixture.nativeElement as HTMLElement;
        const img = nativeElement.querySelector('img')!;
        expect(img.src).toBe(`${IMG_BASE_URL}/img.png`);
        expect(img.srcset)
            .toBe(`${IMG_BASE_URL}/img.png?w=100 1x, ${IMG_BASE_URL}/img.png?w=200 2x`);
      });

      it('should set the `srcset` if `ngSrcset` has only one src defined', () => {
        setupTestingModule({imageLoader});

        const template = `
           <img ngSrc="img.png" ngSrcset="100w" width="100" height="50">
         `;
        const fixture = createTestComponent(template);
        fixture.detectChanges();

        const nativeElement = fixture.nativeElement as HTMLElement;
        const img = nativeElement.querySelector('img')!;
        expect(img.src.trim()).toBe(`${IMG_BASE_URL}/img.png`);
        expect(img.srcset.trim()).toBe(`${IMG_BASE_URL}/img.png?w=100 100w`);
      });

      it('should set the `srcset` if `ngSrcSet` has extra spaces', () => {
        setupTestingModule({imageLoader});

        const template = `
           <img ngSrc="img.png" ngSrcset="  100w,  200w   " width="100" height="50">
         `;
        const fixture = createTestComponent(template);
        fixture.detectChanges();

        const nativeElement = fixture.nativeElement as HTMLElement;
        const img = nativeElement.querySelector('img')!;
        expect(img.src).toBe(`${IMG_BASE_URL}/img.png`);
        expect(img.srcset)
            .toBe(`${IMG_BASE_URL}/img.png?w=100 100w, ${IMG_BASE_URL}/img.png?w=200 200w`);
      });

      it('should set the `srcset` if `ngSrcSet` has a trailing comma', () => {
        setupTestingModule({imageLoader});

        const template = `
           <img ngSrc="img.png" ngSrcset="1x, 2x," width="100" height="50">
         `;
        const fixture = createTestComponent(template);
        fixture.detectChanges();

        const nativeElement = fixture.nativeElement as HTMLElement;
        const img = nativeElement.querySelector('img')!;
        expect(img.src).toBe(`${IMG_BASE_URL}/img.png`);
        expect(img.srcset)
            .toBe(`${IMG_BASE_URL}/img.png?w=100 1x, ${IMG_BASE_URL}/img.png?w=200 2x`);
      });

      it('should set the `srcset` if `ngSrcSet` has 3+ srcs', () => {
        setupTestingModule({imageLoader});

        const template = `
           <img ngSrc="img.png" ngSrcset="100w, 200w, 300w" width="100" height="50">
         `;
        const fixture = createTestComponent(template);
        fixture.detectChanges();

        const nativeElement = fixture.nativeElement as HTMLElement;
        const img = nativeElement.querySelector('img')!;
        expect(img.src).toBe(`${IMG_BASE_URL}/img.png`);
        expect(img.srcset)
            .toBe(
                `${IMG_BASE_URL}/img.png?w=100 100w, ` +
                `${IMG_BASE_URL}/img.png?w=200 200w, ` +
                `${IMG_BASE_URL}/img.png?w=300 300w`);
      });

      it('should set the `srcset` if `ngSrcSet` has decimal density descriptors', () => {
        setupTestingModule({imageLoader});

        const template = `
           <img ngSrc="img.png" ngSrcset="1.75x, 2.5x, 3x" width="100" height="50">
         `;
        const fixture = createTestComponent(template);
        fixture.detectChanges();

        const nativeElement = fixture.nativeElement as HTMLElement;
        const img = nativeElement.querySelector('img')!;
        expect(img.src).toBe(`${IMG_BASE_URL}/img.png`);
        expect(img.srcset)
            .toBe(
                `${IMG_BASE_URL}/img.png?w=175 1.75x, ` +
                `${IMG_BASE_URL}/img.png?w=250 2.5x, ` +
                `${IMG_BASE_URL}/img.png?w=300 3x`);
      });
    });

    describe('sizes attribute', () => {
      it('should pass through the sizes attribute', () => {
        setupTestingModule();

        const template = '<img ngSrc="path/img.png" width="150" height="50" ' +
            'sizes="(max-width: 768px) 100vw, (max-width: 1200px) 50vw, 33vw">';
        const fixture = createTestComponent(template);
        fixture.detectChanges();

        const nativeElement = fixture.nativeElement as HTMLElement;
        const img = nativeElement.querySelector('img')!;

        expect(img.getAttribute('sizes'))
            .toBe('(max-width: 768px) 100vw, (max-width: 1200px) 50vw, 33vw');
      });

      it('should throw if a complex `sizes` is used', () => {
        setupTestingModule();

        const template =
            '<img ngSrc="path/img.png" width="100" height="50" sizes="(min-width: 768px) 500px, 100vw">';
        expect(() => {
          const fixture = createTestComponent(template);
          fixture.detectChanges();
        })
            .toThrowError(
                'NG02952: The NgOptimizedImage directive has detected that `sizes` was set to a string including pixel values. ' +
                'For automatic `srcset` generation, `sizes` must only include responsive values, such as `sizes="50vw"` or ' +
                '`sizes="(min-width: 768px) 50vw, 100vw"`. To fix this, modify the `sizes` attribute, or provide your own \`ngSrcset\` value directly.');
      });
      it('should throw if a complex `sizes` is used with srcset', () => {
        setupTestingModule();

        const template =
            '<img ngSrc="path/img.png" width="100" height="50" sizes="(min-width: 768px) 500px, 100vw" srcset="www.example.com/img.png?w=500 768w, www.example.com/img.png?w=2000" >';
        expect(() => {
          const fixture = createTestComponent(template);
          fixture.detectChanges();
        })
            .toThrowError(
                'NG02952: The NgOptimizedImage directive has detected that `sizes` was set to a string including pixel values. ' +
                'For automatic `srcset` generation, `sizes` must only include responsive values, such as `sizes="50vw"` or ' +
                '`sizes="(min-width: 768px) 50vw, 100vw"`. To fix this, modify the `sizes` attribute, or provide your own \`ngSrcset\` value directly.');
      });
      it('should not throw if a complex `sizes` is used with ngSrcset', () => {
        setupTestingModule();

        const template =
            '<img ngSrc="path/img.png" width="100" height="50" sizes="(min-width: 768px) 500px, 100vw" ngSrcset="100w, 200w">';
        expect(() => {
          const fixture = createTestComponent(template);
          fixture.detectChanges();
        }).not.toThrow();
      });
    });

    describe('automatic srcset generation', () => {
      const imageLoader = (config: ImageLoaderConfig) => {
        const width = config.width ? `?w=${config.width}` : ``;
        return `${IMG_BASE_URL}/${config.src}${width}`;
      };

      it('should add a responsive srcset to the img element if sizes attribute exists', () => {
        setupTestingModule({imageLoader});

        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'))
            .toBe(`${IMG_BASE_URL}/img?w=640 640w, ${IMG_BASE_URL}/img?w=750 750w, ${
                IMG_BASE_URL}/img?w=828 828w, ${IMG_BASE_URL}/img?w=1080 1080w, ${
                IMG_BASE_URL}/img?w=1200 1200w, ${IMG_BASE_URL}/img?w=1920 1920w, ${
                IMG_BASE_URL}/img?w=2048 2048w, ${IMG_BASE_URL}/img?w=3840 3840w`);
      });

      it('should use the long responsive srcset if sizes attribute exists and is less than 100vw',
         () => {
           setupTestingModule({imageLoader});

           const template = `
      <img ngSrc="img" width="100" height="50" sizes="2vw">
    `;
           const fixture = createTestComponent(template);
           fixture.detectChanges();

           const nativeElement = fixture.nativeElement as HTMLElement;
           const img = nativeElement.querySelector('img')!;
           expect(img.getAttribute('srcset'))
               .toBe(`${IMG_BASE_URL}/img?w=16 16w, ${IMG_BASE_URL}/img?w=32 32w, ${
                   IMG_BASE_URL}/img?w=48 48w, ${IMG_BASE_URL}/img?w=64 64w, ${
                   IMG_BASE_URL}/img?w=96 96w, ${IMG_BASE_URL}/img?w=128 128w, ${
                   IMG_BASE_URL}/img?w=256 256w, ${IMG_BASE_URL}/img?w=384 384w, ${
                   IMG_BASE_URL}/img?w=640 640w, ${IMG_BASE_URL}/img?w=750 750w, ${
                   IMG_BASE_URL}/img?w=828 828w, ${IMG_BASE_URL}/img?w=1080 1080w, ${
                   IMG_BASE_URL}/img?w=1200 1200w, ${IMG_BASE_URL}/img?w=1920 1920w, ${
                   IMG_BASE_URL}/img?w=2048 2048w, ${IMG_BASE_URL}/img?w=3840 3840w`);
         });

      it('should add a fixed srcset to the img element if sizes attribute does not exist', () => {
        setupTestingModule({imageLoader});

        const template = `
      <img ngSrc="img" width="100" height="50">
    `;
        const fixture = createTestComponent(template);
        fixture.detectChanges();

        const nativeElement = fixture.nativeElement as HTMLElement;
        const img = nativeElement.querySelector('img')!;
        expect(img.getAttribute('srcset'))
            .toBe(`${IMG_BASE_URL}/img?w=100 1x, ${IMG_BASE_URL}/img?w=200 2x`);
      });

      it('should use a custom breakpoint set if one is provided', () => {
        const imageConfig = {
          breakpoints: [16, 32, 48, 64, 96, 128, 256, 384, 640, 1280, 3840],
        };
        setupTestingModule({imageLoader, imageConfig});

        const template = `
      <img ngSrc="img" width="100" height="50" sizes="2vw">
    `;
        const fixture = createTestComponent(template);
        fixture.detectChanges();
        const nativeElement = fixture.nativeElement as HTMLElement;
        const img = nativeElement.querySelector('img')!;
        expect(img.getAttribute('srcset'))
            .toBe(`${IMG_BASE_URL}/img?w=16 16w, ${IMG_BASE_URL}/img?w=32 32w, ${
                IMG_BASE_URL}/img?w=48 48w, ${IMG_BASE_URL}/img?w=64 64w, ${
                IMG_BASE_URL}/img?w=96 96w, ${IMG_BASE_URL}/img?w=128 128w, ${
                IMG_BASE_URL}/img?w=256 256w, ${IMG_BASE_URL}/img?w=384 384w, ${
                IMG_BASE_URL}/img?w=640 640w, ${IMG_BASE_URL}/img?w=1280 1280w, ${
                IMG_BASE_URL}/img?w=3840 3840w`);
      });

      it('should sort custom breakpoint set', () => {
        const imageConfig = {
          breakpoints: [48, 16, 3840, 640, 1280],
        };
        setupTestingModule({imageLoader, imageConfig});

        const template = `
      <img ngSrc="img" width="100" height="50" sizes="2vw">
    `;
        const fixture = createTestComponent(template);
        fixture.detectChanges();
        const nativeElement = fixture.nativeElement as HTMLElement;
        const img = nativeElement.querySelector('img')!;
        expect(img.getAttribute('srcset'))
            .toBe(`${IMG_BASE_URL}/img?w=16 16w, ${IMG_BASE_URL}/img?w=48 48w, ${
                IMG_BASE_URL}/img?w=640 640w, ${IMG_BASE_URL}/img?w=1280 1280w, ${
                IMG_BASE_URL}/img?w=3840 3840w`);
      });

      it('should disable automatic srcset generation if "disableOptimizedSrcset" attribute is set',
         () => {
           setupTestingModule({imageLoader});

           const template = `
      <img ngSrc="img" width="100" height="50" sizes="50vw" disableOptimizedSrcset>
    `;
           const fixture = createTestComponent(template);
           fixture.detectChanges();
           const nativeElement = fixture.nativeElement as HTMLElement;
           const img = nativeElement.querySelector('img')!;
           expect(img.getAttribute('srcset')).toBeNull();
         });
    });
  });
});

// Helpers

// Base URL that can be used in tests to construct absolute URLs.
const IMG_BASE_URL = {
  // Use `toString` here to delay referencing the `window` until the tests
  // execution starts, otherwise the `window` might not be defined in Node env.
  toString: () => window.location.origin
};

const ANGULAR_LOGO_BASE64 =
    'data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCAyNTAgMjUwIj4KICAgIDxwYXRoIGZpbGw9IiNERDAwMzEiIGQ9Ik0xMjUgMzBMMzEuOSA2My4ybDE0LjIgMTIzLjFMMTI1IDIzMGw3OC45LTQzLjcgMTQuMi0xMjMuMXoiIC8+CiAgICA8cGF0aCBmaWxsPSIjQzMwMDJGIiBkPSJNMTI1IDMwdjIyLjItLjFWMjMwbDc4LjktNDMuNyAxNC4yLTEyMy4xTDEyNSAzMHoiIC8+CiAgICA8cGF0aCAgZmlsbD0iI0ZGRkZGRiIgZD0iTTEyNSA1Mi4xTDY2LjggMTgyLjZoMjEuN2wxMS43LTI5LjJoNDkuNGwxMS43IDI5LjJIMTgzTDEyNSA1Mi4xem0xNyA4My4zaC0zNGwxNy00MC45IDE3IDQwLjl6IiAvPgogIDwvc3ZnPg==';

@Component({selector: 'test-cmp', template: ''})
class TestComponent {
  width = 100;
  height = 50;
  ngSrc = 'img.png';
  priority = false;
}

function setupTestingModule(config?: {
  imageConfig?: ImageConfig,
  imageLoader?: ImageLoader,
  extraProviders?: Provider[],
  component?: Type<unknown>
}) {
  const defaultLoader = (config: ImageLoaderConfig) => {
    const isAbsolute = /^https?:\/\//.test(config.src);
    return isAbsolute ? config.src : window.location.origin + '/' + config.src;
  };
  const loader = config?.imageLoader || defaultLoader;
  const extraProviders = config?.extraProviders || [];
  const providers: Provider[] = [
    {provide: DOCUMENT, useValue: window.document}, {provide: IMAGE_LOADER, useValue: loader},
    ...extraProviders
  ];
  if (config?.imageConfig) {
    providers.push({provide: IMAGE_CONFIG, useValue: config.imageConfig});
  }

  TestBed.configureTestingModule({
    declarations: [config?.component ?? TestComponent],
    // Note: the `NgOptimizedImage` directive is experimental and is not a part of the
    // `CommonModule` yet, so it's imported separately.
    imports: [CommonModule, NgOptimizedImage],
    providers
  });
}

function createTestComponent(template: string): ComponentFixture<TestComponent> {
  return TestBed.overrideComponent(TestComponent, {set: {template: template}})
      .createComponent(TestComponent);
}