diff --git a/adev/src/app/core/services/content-loader.service.spec.ts b/adev/src/app/core/services/content-loader.service.spec.ts
index 1ab71a44d34..3b1ce041deb 100644
--- a/adev/src/app/core/services/content-loader.service.spec.ts
+++ b/adev/src/app/core/services/content-loader.service.spec.ts
@@ -6,23 +6,193 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
+import {HttpErrorResponse, provideHttpClient} from '@angular/common/http';
+import {HttpTestingController, provideHttpClientTesting} from '@angular/common/http/testing';
 import {TestBed} from '@angular/core/testing';
-
+import {DocContent} from '@angular/docs';
 import {ContentLoader} from './content-loader.service';
-import {HttpClientTestingModule} from '@angular/common/http/testing';
 
 describe('ContentLoader', () => {
   let service: ContentLoader;
+  let httpTestingController: HttpTestingController;
 
   beforeEach(() => {
     TestBed.configureTestingModule({
-      providers: [ContentLoader],
-      imports: [HttpClientTestingModule],
+      providers: [ContentLoader, provideHttpClient(), provideHttpClientTesting()],
     });
+
     service = TestBed.inject(ContentLoader);
+    httpTestingController = TestBed.inject(HttpTestingController);
   });
 
-  it('should be created', () => {
-    expect(service).toBeTruthy();
+  afterEach(() => {
+    httpTestingController.verify();
+  });
+
+  describe('getContent', () => {
+    it('should fetch content successfully', async () => {
+      const path = 'test-document.md.html';
+      const mockContent = '<h1>Test Document</h1>';
+      const expectedDocContent: DocContent = {
+        contents: mockContent,
+        id: path,
+      };
+
+      const contentPromise = service.getContent(path);
+
+      const req = httpTestingController.expectOne(`assets/content/${path}`);
+      expect(req.request.method).toEqual('GET');
+      expect(req.request.responseType).toEqual('text');
+      req.flush(mockContent);
+
+      const result = await contentPromise;
+      expect(result).toEqual(expectedDocContent);
+    });
+
+    it('should add .md.html extension when path has no extension', async () => {
+      const path = 'test-document';
+      const expectedPath = 'test-document.md.html';
+      const mockContent = '<h1>Test Document</h1>';
+
+      const contentPromise = service.getContent(path);
+
+      const req = httpTestingController.expectOne(`assets/content/${expectedPath}`);
+      expect(req.request.method).toEqual('GET');
+      req.flush(mockContent);
+
+      const result = await contentPromise;
+      expect(result.id).toEqual(expectedPath);
+      expect(result.contents).toEqual(mockContent);
+    });
+
+    it('should not modify path when it already has an extension', async () => {
+      const path = 'test-document.html';
+      const mockContent = '<h1>Test Document</h1>';
+
+      const contentPromise = service.getContent(path);
+
+      const req = httpTestingController.expectOne(`assets/content/${path}`);
+      req.flush(mockContent);
+
+      const result = await contentPromise;
+      expect(result.id).toEqual(path);
+    });
+
+    it('should cache content and return cached version on subsequent calls', async () => {
+      const path = 'cached-document.md.html';
+      const mockContent = '<h1>Cached Document</h1>';
+
+      // First call
+      const firstCallPromise = service.getContent(path);
+      const req1 = httpTestingController.expectOne(`assets/content/${path}`);
+      req1.flush(mockContent);
+      const firstResult = await firstCallPromise;
+
+      // Second call - should use cache, no HTTP request
+      const secondResult = await service.getContent(path);
+
+      expect(firstResult).toEqual(secondResult);
+      expect(firstResult.contents).toEqual(mockContent);
+      httpTestingController.expectNone(`assets/content/${path}`);
+    });
+
+    it('should handle 404 errors and keep them in cache', async () => {
+      const path = 'non-existent.md.html';
+
+      const contentPromise = service.getContent(path);
+
+      const req = httpTestingController.expectOne(`assets/content/${path}`);
+      req.flush('Not Found', {status: 404, statusText: 'Not Found'});
+
+      try {
+        await contentPromise;
+        fail('Expected promise to be rejected');
+      } catch (error) {
+        expect(error).toBeInstanceOf(HttpErrorResponse);
+        expect((error as HttpErrorResponse).status).toBe(404);
+      }
+
+      // Second call should also fail without making another HTTP request
+      // because 404 errors are cached
+      try {
+        await service.getContent(path);
+        fail('Expected second call to be rejected');
+      } catch (error) {
+        expect(error).toBeInstanceOf(HttpErrorResponse);
+        expect((error as HttpErrorResponse).status).toBe(404);
+      }
+      httpTestingController.expectNone(`assets/content/${path}`);
+    });
+
+    it('should not cache non-404 errors and retry on subsequent calls', async () => {
+      const path = 'server-error.md.html';
+
+      // First call - server error
+      const firstCallPromise = service.getContent(path);
+      const req1 = httpTestingController.expectOne(`assets/content/${path}`);
+      req1.flush('Server Error', {status: 500, statusText: 'Internal Server Error'});
+
+      try {
+        await firstCallPromise;
+        fail('Expected first call to be rejected');
+      } catch (error) {
+        expect(error).toBeInstanceOf(HttpErrorResponse);
+        expect((error as HttpErrorResponse).status).toBe(500);
+      }
+
+      // Second call should make another HTTP request since 500 errors are not cached
+      const secondCallPromise = service.getContent(path);
+      const req2 = httpTestingController.expectOne(`assets/content/${path}`);
+      req2.flush('Success content');
+
+      const result = await secondCallPromise;
+      expect(result.contents).toEqual('Success content');
+    });
+
+    it('should handle network errors and not cache them', async () => {
+      const path = 'network-error.md.html';
+
+      // First call - network error
+      const firstCallPromise = service.getContent(path);
+      const req1 = httpTestingController.expectOne(`assets/content/${path}`);
+      req1.error(new ProgressEvent('Network error'));
+
+      try {
+        await firstCallPromise;
+        fail('Expected first call to be rejected');
+      } catch (error) {
+        expect(error).toBeInstanceOf(HttpErrorResponse);
+      }
+
+      // Second call should make another HTTP request since network errors are not cached
+      const secondCallPromise = service.getContent(path);
+      const req2 = httpTestingController.expectOne(`assets/content/${path}`);
+      req2.flush('Success after network error');
+
+      const result = await secondCallPromise;
+      expect(result.contents).toEqual('Success after network error');
+    });
+
+    it('should handle paths with different extensions correctly', async () => {
+      const testCases = [
+        {input: 'document.txt', expected: 'document.txt'},
+        {input: 'document.json', expected: 'document.json'},
+        {input: 'document.xml', expected: 'document.xml'},
+        {input: 'document', expected: 'document.md.html'},
+      ];
+
+      for (const testCase of testCases) {
+        const mockContent = `Content for ${testCase.input}`;
+
+        const contentPromise = service.getContent(testCase.input);
+
+        const req = httpTestingController.expectOne(`assets/content/${testCase.expected}`);
+        req.flush(mockContent);
+
+        const result = await contentPromise;
+        expect(result.id).toEqual(testCase.expected);
+        expect(result.contents).toEqual(mockContent);
+      }
+    });
   });
 });