diff --git a/packages/backend/test/tests/mfm.ts b/packages/backend/test/tests/mfm.ts
deleted file mode 100644
index 884f39d7fb..0000000000
--- a/packages/backend/test/tests/mfm.ts
+++ /dev/null
@@ -1,89 +0,0 @@
-import * as assert from 'assert';
-import * as mfm from 'mfm-js';
-
-import { toHtml } from '../../src/mfm/to-html.js';
-import { fromHtml } from '../../src/mfm/from-html.js';
-
-describe('toHtml', () => {
-	test('br', () => {
-		const input = 'foo\nbar\nbaz';
-		const output = '<p><span>foo<br>bar<br>baz</span></p>';
-		assert.equal(toHtml(mfm.parse(input)), output);
-	});
-
-	test('br alt', () => {
-		const input = 'foo\r\nbar\rbaz';
-		const output = '<p><span>foo<br>bar<br>baz</span></p>';
-		assert.equal(toHtml(mfm.parse(input)), output);
-	});
-});
-
-describe('fromHtml', () => {
-	test('p', () => {
-		assert.deepStrictEqual(fromHtml('<p>a</p><p>b</p>'), 'a\n\nb');
-	});
-
-	test('block element', () => {
-		assert.deepStrictEqual(fromHtml('<div>a</div><div>b</div>'), 'a\nb');
-	});
-
-	test('inline element', () => {
-		assert.deepStrictEqual(fromHtml('<ul><li>a</li><li>b</li></ul>'), 'a\nb');
-	});
-
-	test('block code', () => {
-		assert.deepStrictEqual(fromHtml('<pre><code>a\nb</code></pre>'), '```\na\nb\n```');
-	});
-
-	test('inline code', () => {
-		assert.deepStrictEqual(fromHtml('<code>a</code>'), '`a`');
-	});
-
-	test('quote', () => {
-		assert.deepStrictEqual(fromHtml('<blockquote>a\nb</blockquote>'), '> a\n> b');
-	});
-
-	test('br', () => {
-		assert.deepStrictEqual(fromHtml('<p>abc<br><br/>d</p>'), 'abc\n\nd');
-	});
-
-	test('link with different text', () => {
-		assert.deepStrictEqual(fromHtml('<p>a <a href="https://example.com/b">c</a> d</p>'), 'a [c](https://example.com/b) d');
-	});
-
-	test('link with different text, but not encoded', () => {
-		assert.deepStrictEqual(fromHtml('<p>a <a href="https://example.com/ä">c</a> d</p>'), 'a [c](<https://example.com/ä>) d');
-	});
-
-	test('link with same text', () => {
-		assert.deepStrictEqual(fromHtml('<p>a <a href="https://example.com/b">https://example.com/b</a> d</p>'), 'a https://example.com/b d');
-	});
-
-	test('link with same text, but not encoded', () => {
-		assert.deepStrictEqual(fromHtml('<p>a <a href="https://example.com/ä">https://example.com/ä</a> d</p>'), 'a <https://example.com/ä> d');
-	});
-
-	test('link with no url', () => {
-		assert.deepStrictEqual(fromHtml('<p>a <a href="b">c</a> d</p>'), 'a [c](b) d');
-	});
-
-	test('link without href', () => {
-		assert.deepStrictEqual(fromHtml('<p>a <a>c</a> d</p>'), 'a c d');
-	});
-
-	test('link without text', () => {
-		assert.deepStrictEqual(fromHtml('<p>a <a href="https://example.com/b"></a> d</p>'), 'a https://example.com/b d');
-	});
-
-	test('link without both', () => {
-		assert.deepStrictEqual(fromHtml('<p>a <a></a> d</p>'), 'a  d');
-	});
-
-	test('mention', () => {
-		assert.deepStrictEqual(fromHtml('<p>a <a href="https://example.com/@user" class="u-url mention">@user</a> d</p>'), 'a @user@example.com d');
-	});
-
-	test('hashtag', () => {
-		assert.deepStrictEqual(fromHtml('<p>a <a href="https://example.com/tags/a">#a</a> d</p>', ['#a']), 'a #a d');
-	});
-});
diff --git a/packages/backend/test/tests/extract-mentions.ts b/packages/backend/test/unit/extract-mentions.ts
similarity index 81%
rename from packages/backend/test/tests/extract-mentions.ts
rename to packages/backend/test/unit/extract-mentions.ts
index e81d04c2db..66d32be1c5 100644
--- a/packages/backend/test/tests/extract-mentions.ts
+++ b/packages/backend/test/unit/extract-mentions.ts
@@ -1,11 +1,11 @@
 import * as assert from 'assert';
 
 import { parse } from 'mfm-js';
-import { extractMentions } from '../../src/misc/extract-mentions.js';
+import { extractMentions } from '@/misc/extract-mentions.js';
 
 describe('Extract mentions', () => {
 	test('simple', () => {
-		const ast = parse('@foo @bar @baz')!;
+		const ast = parse('@foo @bar @baz');
 		const mentions = extractMentions(ast);
 		assert.deepStrictEqual(mentions, [{
 			username: 'foo',
@@ -23,7 +23,7 @@ describe('Extract mentions', () => {
 	});
 
 	test('nested', () => {
-		const ast = parse('@foo **@bar** @baz')!;
+		const ast = parse('@foo **@bar** @baz');
 		const mentions = extractMentions(ast);
 		assert.deepStrictEqual(mentions, [{
 			username: 'foo',
diff --git a/packages/backend/test/unit/mfm.ts b/packages/backend/test/unit/mfm.ts
new file mode 100644
index 0000000000..d7ef14dfa3
--- /dev/null
+++ b/packages/backend/test/unit/mfm.ts
@@ -0,0 +1,109 @@
+import * as assert from 'assert';
+import * as mfm from 'mfm-js';
+import { Test } from '@nestjs/testing';
+
+import { CoreModule } from '@/core/CoreModule.js';
+import { MfmService } from '@/core/MfmService.js';
+import { GlobalModule } from '@/GlobalModule.js';
+
+describe('toHtml', () => {
+	let mfmService: MfmService;
+
+	beforeEach(async () => {
+		const app = await Test.createTestingModule({
+			imports: [GlobalModule, CoreModule],
+		}).compile();
+		mfmService = app.get<MfmService>(MfmService);
+	});
+
+	test('br', () => {
+		const input = 'foo\nbar\nbaz';
+		const output = '<p><span>foo<br>bar<br>baz</span></p>';
+		assert.equal(mfmService.toHtml(mfm.parse(input)), output);
+	});
+
+	test('br alt', () => {
+		const input = 'foo\r\nbar\rbaz';
+		const output = '<p><span>foo<br>bar<br>baz</span></p>';
+		assert.equal(mfmService.toHtml(mfm.parse(input)), output);
+	});
+});
+
+describe('fromHtml', () => {
+	let mfmService: MfmService;
+
+	beforeEach(async () => {
+		const app = await Test.createTestingModule({
+			imports: [GlobalModule, CoreModule],
+		}).compile();
+		mfmService = app.get<MfmService>(MfmService);
+	});
+
+	test('p', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<p>a</p><p>b</p>'), 'a\n\nb');
+	});
+
+	test('block element', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<div>a</div><div>b</div>'), 'a\nb');
+	});
+
+	test('inline element', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<ul><li>a</li><li>b</li></ul>'), 'a\nb');
+	});
+
+	test('block code', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<pre><code>a\nb</code></pre>'), '```\na\nb\n```');
+	});
+
+	test('inline code', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<code>a</code>'), '`a`');
+	});
+
+	test('quote', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<blockquote>a\nb</blockquote>'), '> a\n> b');
+	});
+
+	test('br', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<p>abc<br><br/>d</p>'), 'abc\n\nd');
+	});
+
+	test('link with different text', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<p>a <a href="https://example.com/b">c</a> d</p>'), 'a [c](https://example.com/b) d');
+	});
+
+	test('link with different text, but not encoded', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<p>a <a href="https://example.com/ä">c</a> d</p>'), 'a [c](<https://example.com/ä>) d');
+	});
+
+	test('link with same text', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<p>a <a href="https://example.com/b">https://example.com/b</a> d</p>'), 'a https://example.com/b d');
+	});
+
+	test('link with same text, but not encoded', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<p>a <a href="https://example.com/ä">https://example.com/ä</a> d</p>'), 'a <https://example.com/ä> d');
+	});
+
+	test('link with no url', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<p>a <a href="b">c</a> d</p>'), 'a [c](b) d');
+	});
+
+	test('link without href', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<p>a <a>c</a> d</p>'), 'a c d');
+	});
+
+	test('link without text', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<p>a <a href="https://example.com/b"></a> d</p>'), 'a https://example.com/b d');
+	});
+
+	test('link without both', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<p>a <a></a> d</p>'), 'a  d');
+	});
+
+	test('mention', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<p>a <a href="https://example.com/@user" class="u-url mention">@user</a> d</p>'), 'a @user@example.com d');
+	});
+
+	test('hashtag', () => {
+		assert.deepStrictEqual(mfmService.fromHtml('<p>a <a href="https://example.com/tags/a">#a</a> d</p>', ['#a']), 'a #a d');
+	});
+});