docs: add testing section

Author: nartc

apps/astro-docs/src/content/docs/blog/v2.mdx

@@ -32,6 +32,7 @@ Consequently, even though the surface-level APIs of v1 and v2 are similar, as bo
 - Better composability 🧩
 - Better `Portal` powered components 🪞
 - Improved documentation 📖
+- Testing (Experimental) 🧪
 
 While this list might seem modest at first glance, the core improvements in Angular Three v2 unlock a wealth of potential that has been incorporated into other packages like `angular-three-soba`, `angular-three-cannon`, and `angular-three-postprocessing`.
 
@@ -374,6 +375,47 @@ Angular Three v2 documentation is powered by [Starlight](https://starlight.astro
 
 This very release blog post is powered by the same stack, making it a delight to work with. With this, we aim to provide a superior documentation experience for Angular Three users.
 
+### Testing (Experimental) 🧪
+
+Angular Three v2 introduces an experimental testing module available through the `angular-three/testing` entry point. This module provides utilities to help you write unit tests for your Angular Three components and scene graphs.
+
+:::caution
+
+The testing API is currently in Developer Preview and may be subject to changes without following semantic versioning.
+
+:::
+
+### Key Features
+
+1. **NgtTestBed**: A utility that extends Angular's TestBed, specifically tailored for Angular Three components.
+2. **Mocked Rendering**: Tests run without actual 3D rendering, focusing on scene graph state assertions.
+3. **Event Simulation**: Ability to simulate Three.js-specific events like `click`, `pointerover`, etc.
+4. **Animation Frame Control**: Methods to advance animation frames for testing time-based behaviors.
+
+### Basic Usage
+
+Here's a simple example of how you might use the testing utilities:
+
+```ts
+import { NgtTestBed } from 'angular-three/testing';
+
+describe('MyThreeComponent', () => {
+  it('should render a mesh', async () => {
+    const { scene, fireEvent, advance } = NgtTestBed.create(MyThreeComponent);
+
+    expect(scene.children.length).toBe(1);
+    const mesh = scene.children[0] as THREE.Mesh;
+    expect(mesh.isMesh).toBe(true);
+
+    await fireEvent(mesh, 'click');
+    // Assert changes after click
+
+    await advance(1); // Advance one frame
+    // Assert changes after animation
+  });
+});
+```
+
 ## Getting Started
 
 To get started with Angular Three v2, check out the [documentation](https://angularthree.org/).