implemented a lot of features

tests/unit/content.spec.ts

@@ -0,0 +1,45 @@
+import { test } from '@japa/runner'
+import yencode from 'yencode'
+import { sniffContentType } from '#lib/content/index'
+import { crc32Hex, decodeSegment, YencError } from '#lib/yenc/index'
+
+test.group('content / sniffContentType', () => {
+  test('recognises containers and media by magic bytes', ({ assert }) => {
+    const magic = (hex: string, pad = 16) => Buffer.concat([Buffer.from(hex, 'hex'), Buffer.alloc(pad)])
+    assert.equal(sniffContentType(Buffer.concat([Buffer.from('nzbe'), Buffer.alloc(40)])), 'nzbe')
+    assert.equal(sniffContentType(magic('5041523200504b54')), 'par2')
+    assert.equal(sniffContentType(magic('526172211a070100')), 'rar5')
+    assert.equal(sniffContentType(magic('526172211a0700')), 'rar4')
+    assert.equal(sniffContentType(magic('1a45dfa3')), 'matroska')
+    assert.equal(sniffContentType(magic('0000001866747970')), 'mp4')
+    assert.equal(sniffContentType(magic('28b52ffd')), 'zstd')
+    assert.equal(sniffContentType(Buffer.from('<?xml version="1.0"?>\n<!DOCTYPE nzb PUBLIC "x">')), 'nzb')
+    assert.isNull(sniffContentType(Buffer.from('plain text')))
+    assert.equal(sniffContentType(magic('ffd8ffe0')), 'jpeg')
+    assert.equal(sniffContentType(magic('89504e470d0a1a0a')), 'png')
+    assert.equal(sniffContentType(Buffer.concat([Buffer.from('ID3'), Buffer.alloc(16)])), 'mp3')
+    assert.equal(sniffContentType(Buffer.concat([Buffer.from('fLaC'), Buffer.alloc(16)])), 'flac')
+    assert.equal(sniffContentType(Buffer.from('RIFF\x00\x00\x00\x00AVI LIST', 'latin1')), 'avi')
+
+    // UDF (Blu-ray) volume recognition sequence at 32 KiB
+    const udf = Buffer.alloc(0x9000)
+    udf.write('BEA01', 0x8001, 'latin1')
+    udf.write('NSR03', 0x8801, 'latin1')
+    assert.equal(sniffContentType(udf), 'udf')
+  })
+})
+
+test.group('yenc / lenientSize', () => {
+  test('decodes a part whose declared size leaves out a header, still checking the CRC', ({ assert }) => {
+    const data = Buffer.concat([Buffer.from('nzbe'), Buffer.alloc(16, 7), Buffer.from('ciphertext-here')])
+    const declared = data.length - 20
+    const body = Buffer.from(
+      `=ybegin part=1 line=128 size=${declared} name=f6dd6b156692a52b.bin\r\n=ypart begin=1 end=${declared}\r\n` +
+        yencode.encode(data).toString('latin1') +
+        `\r\n=yend size=${declared} part=1 pcrc32=${crc32Hex(data)}`,
+      'latin1'
+    )
+    assert.throws(() => decodeSegment(body), YencError as any)
+    assert.isTrue(decodeSegment(body, { lenientSize: true }).data.equals(data))
+  })
+})