extract inline images from MFM and Markdown

packages/backend/test/unit/core/activitypub/misc/extract-media-from-mfm.ts

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+/*
+ * SPDX-FileCopyrightText: hazelnoot and other Sharkey contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { extractMediaFromMfm } from '@/core/activitypub/misc/extract-media-from-mfm.js';
+
+describe(extractMediaFromMfm, () => {
+	it('should return empty for empty input', () => {
+		const result = extractMediaFromMfm('');
+		expect(result).toEqual([]);
+	});
+
+	it('should return empty for invalid input', () => {
+		const result = extractMediaFromMfm('*broken markdown\0');
+		expect(result).toEqual([]);
+	});
+
+	it('should extract all image links', () => {
+		const result = extractMediaFromMfm(`
+			![1](https://example.com/images/1.png)
+			![](https://example.com/images/2.png)
+			**![3](https://example.com/images/3.png)**
+		`);
+
+		expect(result).toEqual([
+			{
+				type: 'Image',
+				url: 'https://example.com/images/1.png',
+				name: '1',
+			},
+			{
+				type: 'Image',
+				url: 'https://example.com/images/2.png',
+				name: null,
+			},
+			{
+				type: 'Image',
+				url: 'https://example.com/images/3.png',
+				name: '3',
+			},
+		]);
+	});
+
+	it('should ignore regular links', () => {
+		const result = extractMediaFromMfm(`
+			[1](https://example.com/images/1.png)
+			[](https://example.com/images/2.png)
+			**[3](https://example.com/images/3.png)**
+		`);
+
+		expect(result).toEqual([]);
+	});
+
+	it('should ignore silent links', () => {
+		const result = extractMediaFromMfm(`
+			?[1](https://example.com/images/1.png)
+			?[](https://example.com/images/2.png)
+			**?[3](https://example.com/images/3.png)**
+		`);
+
+		expect(result).toEqual([]);
+	});
+
+	it('should extract complex text', () => {
+		const result = extractMediaFromMfm('![this is an **image** with *complex* text! :owo: 💙](https://example.com/image.png)');
+
+		expect(result).toEqual([
+			{
+				type: 'Image',
+				url: 'https://example.com/image.png',
+				name: 'this is an image with complex text! :owo: 💙',
+			},
+		]);
+	});
+
+	it('should de-duplicate images', () => {
+		const result = extractMediaFromMfm(`
+			![1](https://example.com/images/1.png)
+			![](https://example.com/images/1.png)
+			**![3](https://example.com/images/1.png)**
+		`);
+
+		expect(result).toEqual([
+			{
+				type: 'Image',
+				url: 'https://example.com/images/1.png',
+				name: '3',
+			},
+		]);
+	});
+});