diff --git a/tests/utils/code_markup_parser.test.ts b/tests/utils/code_markup_parser.test.ts
new file mode 100644
index 0000000..a03312d
--- /dev/null
+++ b/tests/utils/code_markup_parser.test.ts
@@ -0,0 +1,138 @@
+import { describe, expect, test } from 'bun:test';
+
+import { CodeMarkupParser } from '../../src/utils/code_markup_parser';
+import type { Facet, FacetLink, FacetMention, FacetTag } from '../../lib/rich_text_lite';
+
+const encoder = new TextEncoder();
+
+function lines(parts: string[]): string {
+  return parts.join('\n');
+}
+
+function facetMention(did: string): FacetMention {
+  return { $type: 'app.bsky.richtext.facet#mention', did: did };
+}
+
+function facetTag(tag: string): FacetTag {
+  return { $type: 'app.bsky.richtext.facet#tag', tag: tag };
+}
+
+function facetFor(text: string, token: string, feature: FacetLink | FacetMention | FacetTag, occurrence = 0): Facet {
+  let start = -1;
+
+  for (let i = 0; i <= occurrence; i++) {
+    start = text.indexOf(token, start + 1);
+  }
+
+  if (start == -1) {
+    throw new Error(`Missing token in test text: ${token}`);
+  }
+
+  return {
+    index: {
+      byteStart: encoder.encode(text.slice(0, start)).byteLength,
+      byteEnd: encoder.encode(text.slice(0, start + token.length)).byteLength,
+    },
+    features: [feature],
+  };
+}
+
+describe('CodeMarkupParser', () => {
+  describe('asSingleSegment', () => {
+    test('returns the whole text as a plain text segment', () => {
+      expect(new CodeMarkupParser('something with `code` etc').asSingleSegment()).toEqual(
+        { kind: 'text', text: 'something with `code` etc', start: 0, end: 25 }
+      );
+    });
+  });
+
+  describe('segments', () => {
+    test('returns a single text segment when no backticks are present', () => {
+      expect(new CodeMarkupParser('plain text').segments()).toEqual([
+        { kind: 'text', text: 'plain text', start: 0, end: 10 },
+      ]);
+    });
+
+    test('splits inline code from surrounding text', () => {
+      expect(new CodeMarkupParser('hello `code` world').segments()).toEqual([
+        { kind: 'text', text: 'hello ', start: 0, end: 6 },
+        { kind: 'inlineCode', text: 'code', start: 6, end: 12 },
+        { kind: 'text', text: ' world', start: 12, end: 18 },
+      ]);
+    });
+
+    test('extracts code blocks with a language', () => {
+      let text = lines([
+        'before',
+        '```ts',
+        'const x = 1;',
+        '```',
+        'after',
+      ]);
+
+      expect(new CodeMarkupParser(text).segments()).toEqual([
+        { kind: 'text', text: 'before\n', start: 0, end: 7 },
+        {
+          kind: 'codeBlock',
+          text: 'const x = 1;\n',
+          language: 'ts',
+          start: 7,
+          end: 30,
+        },
+        { kind: 'text', text: 'after', start: 30, end: 35 },
+      ]);
+    });
+
+    test('extracts code blocks with no language tag', () => {
+      let text = lines([
+        'before',
+        '```',
+        '[config]',
+        'user = root',
+        '```',
+        'after',
+      ]);
+
+      expect(new CodeMarkupParser(text).segments()).toEqual([
+        { kind: 'text', text: 'before\n', start: 0, end: 7 },
+        {
+          kind: 'codeBlock',
+          text: '[config]\nuser = root\n',
+          language: undefined,
+          start: 7,
+          end: 36,
+        },
+        { kind: 'text', text: 'after', start: 36, end: 41 },
+      ]);
+    });
+  });
+
+  describe('removeFacetsInCodeSegments', () => {
+    test('removes facets that overlap code ranges', () => {
+      let text = lines([
+        '@atproto.com new C library #atdev',
+        '',
+        '```c',
+        '#include "atproto.h"',
+        'makePost("hello @atproto.com");',
+        '```',
+        '',
+        "Don't forget the `#include`",
+      ]);
+
+      let atprotoMention = facetFor(text, '@atproto.com', facetMention('did:web:atproto.com'));
+      let atdevTag = facetFor(text, '#atdev', facetTag('atdev'));
+
+      let originalFacets: Facet[] = [
+        atprotoMention,
+        atdevTag,
+        facetFor(text, '#include', facetTag('include')),
+        facetFor(text, '@atproto.com', facetMention('did:web:atproto.com'), 1),
+        facetFor(text, '#include', facetTag('include'), 1),
+      ];
+
+      let filteredFacets = new CodeMarkupParser(text).removeFacetsInCodeSegments(originalFacets);
+      expect(filteredFacets).toEqual([atprotoMention, atdevTag]);
+    });
+  });
+});