feat: add ebook MIME types, fix azw3/mobi detection collision, trust undetectable ebook formats

test/mime.test.js

@@ -113,6 +113,85 @@ describe('outputMimeType — fonts', () => {
   });
 });
 
+describe('outputMimeType — ebooks', () => {
+  it('returns the correct MIME type for each ebook target format', () => {
+    expect(outputMimeType('epub')).toBe('application/epub+zip');
+    expect(outputMimeType('fb2')).toBe('application/x-fictionbook+xml');
+    expect(outputMimeType('mobi')).toBe('application/x-mobipocket-ebook');
+    expect(outputMimeType('azw3')).toBe('application/vnd.amazon.ebook');
+    expect(outputMimeType('pdb')).toBe('application/vnd.palm');
+    expect(outputMimeType('lrf')).toBe('application/octet-stream');
+    expect(outputMimeType('rb')).toBe('application/octet-stream');
+    expect(outputMimeType('snb')).toBe('application/octet-stream');
+    expect(outputMimeType('tcr')).toBe('application/octet-stream');
+  });
+});
+
+describe('resolveInputFormat — azw3/mobi collision', () => {
+  function buildMobiFamilyBuffer() {
+    // PDB header: 8-byte "BOOKMOBI" type+creator magic at offset 60, shared by both
+    // real .mobi and real .azw3 files (confirmed in file-type's source).
+    const buffer = Buffer.alloc(68);
+    buffer.write('BOOKMOBI', 60, 'ascii');
+    return buffer;
+  }
+
+  it('confirms file-type reports mobi-family content as ext "mobi" regardless of which of the two formats it is (documents the collision this fix works around)', async () => {
+    const fixturePath = path.join(import.meta.dirname, 'fixtures', 'sample-mobi-family.bin');
+    await fs.writeFile(fixturePath, buildMobiFamilyBuffer());
+
+    const detected = await detectInputMime(fixturePath);
+    expect(detected).toEqual({ ext: 'mobi', mime: 'application/x-mobipocket-ebook' });
+
+    await fs.unlink(fixturePath);
+  });
+
+  it('accepts a real mobi-family file declared as mobi', async () => {
+    const fixturePath = path.join(import.meta.dirname, 'fixtures', 'sample-mobi-family.bin');
+    await fs.writeFile(fixturePath, buildMobiFamilyBuffer());
+
+    const result = await resolveInputFormat(fixturePath, 'mobi');
+    expect(result).toEqual({ mime: 'application/x-mobipocket-ebook', valid: true });
+
+    await fs.unlink(fixturePath);
+  });
+
+  it('accepts a real mobi-family file declared as azw3 despite file-type reporting it as mobi', async () => {
+    const fixturePath = path.join(import.meta.dirname, 'fixtures', 'sample-mobi-family.bin');
+    await fs.writeFile(fixturePath, buildMobiFamilyBuffer());
+
+    const result = await resolveInputFormat(fixturePath, 'azw3');
+    expect(result).toEqual({ mime: 'application/x-mobipocket-ebook', valid: true });
+
+    await fs.unlink(fixturePath);
+  });
+});
+
+describe('resolveInputFormat — undetectable ebook formats', () => {
+  const undetectableFormats = {
+    fb2: 'application/x-fictionbook+xml',
+    lrf: 'application/octet-stream',
+    pdb: 'application/vnd.palm',
+    rb: 'application/octet-stream',
+    snb: 'application/octet-stream',
+    tcr: 'application/octet-stream',
+  };
+
+  it.each(Object.entries(undetectableFormats))(
+    'trusts the declared format for undetectable %s files',
+    async (declaredFormat, expectedMime) => {
+      const fixturePath = path.join(import.meta.dirname, 'fixtures', `sample.${declaredFormat}`);
+      await fs.writeFile(fixturePath, 'arbitrary bytes with no recognizable magic number');
+
+      const result = await resolveInputFormat(fixturePath, declaredFormat);
+
+      expect(result).toEqual({ mime: expectedMime, valid: true });
+
+      await fs.unlink(fixturePath);
+    }
+  );
+});
+
 describe('resolveInputFormat — dfont', () => {
   it('confirms file-type alone misidentifies the dfont fixture as ico (documents the bug this fix works around)', async () => {
     const fixturePath = path.join(import.meta.dirname, 'fixtures', 'sample.dfont');