test: lt-codes should allow loss and disorder

Author: LittleSound

test/lt.test.ts

@@ -1,29 +1,73 @@
 import fs from 'node:fs/promises'
 import { join } from 'node:path'
 
-import { expect, it } from 'vitest'
+import { describe, expect, it } from 'vitest'
 import { binaryToBlock, blockToBinary, createDecoder, encodeFountain } from '../utils/lt-codes'
 
-it('slice binary', async () => {
-  const input = (await fs.readFile(join('test', 'SampleJPGImage_100kbmb.jpg'), null)).buffer
-  const data = new Uint32Array(input)
-
-  const decoder = createDecoder()
-  let count = 0
-  for (const block of encodeFountain(data, 1000)) {
-    count += 1
-    if (count > 1000)
-      throw new Error('Too many blocks')
-    const binary = blockToBinary(block)
-    // Use the binary to transfer
-    const back = binaryToBlock(binary)
-    const result = decoder.addBlock([back])
-    if (result)
-      break
-  }
-
-  const result = decoder.getDecoded()!
-  expect(result).toBeDefined()
-  expect(result).toBeInstanceOf(Uint32Array)
-  expect(result.length).toBe(data.length)
+describe('lt-codes', () => {
+  it('slice binary', async () => {
+    const input = (await fs.readFile(join('test', 'SampleJPGImage_100kbmb.jpg'), null)).buffer
+    const data = new Uint32Array(input)
+
+    const decoder = createDecoder()
+    let count = 0
+    for (const block of encodeFountain(data, 1000)) {
+      count += 1
+      if (count > 1000)
+        throw new Error('Too many blocks')
+      const binary = blockToBinary(block)
+      // Use the binary to transfer
+      const back = binaryToBlock(binary)
+      const result = decoder.addBlock([back])
+      if (result)
+        break
+    }
+
+    const result = decoder.getDecoded()!
+    expect(result).toBeDefined()
+    expect(result).toBeInstanceOf(Uint32Array)
+    expect(result.length).toBe(data.length)
+  })
+
+  it(`allow loss and disorder`, async () => {
+    const input = (await fs.readFile(join('test', 'SampleJPGImage_100kbmb.jpg'), null)).buffer
+    const data = new Uint32Array(input)
+
+    const decoder = createDecoder()
+    let count = 0
+
+    const packets: Uint32Array[] = []
+
+    // Encode the data
+    for (const block of encodeFountain(data, 1000)) {
+      count += 1
+      if (count > 1000)
+        break
+      packets.push(blockToBinary(block))
+    }
+
+    // Dissupt the order of packets
+    packets.sort(() => Math.random() - 0.5)
+    // Simulate 50% of packet loss
+    packets.length = Math.floor(packets.length * 0.5)
+
+    count = 0
+    // Decode the data
+    for (const packet of packets) {
+      count += 1
+      if (count > 500)
+        throw new Error('Too many blocks')
+
+      // Use the binary to transfer
+      const back = binaryToBlock(packet)
+      const result = decoder.addBlock([back])
+      if (result)
+        break
+    }
+
+    const result = decoder.getDecoded()!
+    expect(result).toBeDefined()
+    expect(result).toBeInstanceOf(Uint32Array)
+    expect(result.length).toBe(data.length)
+  })
 })