Add tests for TS brotli decoder

PiperOrigin-RevId: 527326003

js/bundle_test.js

@@ -15,8 +15,8 @@ const CRC_64_POLY = new Uint32Array([0xD7870F42, 0xC96C5795]);
  * @return {string} footprint
  */
 function calculateCrc64(data) {
-  let crc = new Uint32Array([0xFFFFFFFF, 0xFFFFFFFF]);
+  const crc = new Uint32Array([0xFFFFFFFF, 0xFFFFFFFF]);
-  let c = new Uint32Array(2);
+  const c = new Uint32Array(2);
   for (let i = 0; i < data.length; ++i) {
     c[1] = 0;
     c[0] = (crc[0] ^ data[i]) & 0xFF;
@@ -58,7 +58,7 @@ function checkEntry(entry, data) {
 
 describe("BundleTest", () => {
   const testData = makeTestData();
-  for (let entry in testData) {
+  for (const entry in testData) {
     if (!testData.hasOwnProperty(entry)) {
       continue;
     }

js/bundle_test.ts

@@ -0,0 +1,63 @@
+/* Copyright 2023 Google Inc. All Rights Reserved.
+
+   Distributed under MIT license.
+   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+import {brotliDecode} from "./decode";
+import {makeTestData} from "./test_data";
+
+const CRC_64_POLY = new Uint32Array([0xD7870F42, 0xC96C5795]);
+
+/**
+ * Calculates binary data footprint.
+ */
+function calculateCrc64(data: Int8Array): string {
+  const crc = new Uint32Array([0xFFFFFFFF, 0xFFFFFFFF]);
+  const c = new Uint32Array(2);
+  for (let i = 0; i < data.length; ++i) {
+    c[1] = 0;
+    c[0] = (crc[0] ^ data[i]) & 0xFF;
+    for (let k = 0; k < 8; ++k) {
+      const isOdd = c[0] & 1;
+      c[0] = (c[0] >>> 1) | ((c[1] & 1) << 31);
+      c[1] = c[1] >>> 1;
+      if (isOdd) {
+        c[0] = c[0] ^ CRC_64_POLY[0];
+        c[1] = c[1] ^ CRC_64_POLY[1];
+      }
+    }
+    crc[0] = ((crc[0] >>> 8) | ((crc[1] & 0xFF) << 24)) ^ c[0];
+    crc[1] = (crc[1] >>> 8) ^ c[1];
+  }
+  crc[0] = ~crc[0];
+  crc[1] = ~crc[1];
+
+  let lo = crc[0].toString(16);
+  lo = "0".repeat(8 - lo.length) + lo;
+  let hi = crc[1].toString(16);
+  hi = "0".repeat(8 - hi.length) + hi;
+
+  return hi + lo;
+}
+
+/**
+ * Decompresses data and checks that output footprint is correct.
+ */
+function checkEntry(entry: string, data: Int8Array) {
+  const expectedCrc = entry.substring(0, 16);
+  const decompressed = brotliDecode(data);
+  const crc = calculateCrc64(decompressed);
+  expect(expectedCrc).toEqual(crc);
+}
+
+describe("BundleTest", () => {
+  const testData = makeTestData();
+  for (const entry in testData) {
+    if (!testData.hasOwnProperty(entry)) {
+      continue;
+    }
+    const name = entry.substring(17);
+    const data = testData[entry];
+    it('test_' + name, checkEntry.bind(null, entry, data));
+  }
+});

js/decode_synth_test.js

@@ -7,15 +7,18 @@ import {BrotliDecode} from "./decode.js";
 
 /**
  * NB: Use intermediate chunks to avoid "Maximum call stack size exceeded".
+ *
+ * @param {!Int8Array} bytes
+ * @return {string}
  */
 function bytesToString(bytes) {
   const kChunkSize = 4096;
   if (bytes.length <= kChunkSize) {
     return String.fromCharCode.apply(null, new Uint8Array(bytes));
   }
-  let chunks = [];
+  const chunks = [];
   for (let start = 0; start < bytes.length; start += kChunkSize) {
-    let end = Math.min(start +  4096, bytes.length)
+    const end = Math.min(start + 4096, bytes.length);
     chunks.push(bytesToString(bytes.slice(start, end)));
   }
   return chunks.join('');
@@ -32,6 +35,11 @@ function repeat(char, count) {
   return char.repeat(count);
 }
 
+/**
+ * @param {!Array<number>} compressed
+ * @param {boolean} expectSuccess
+ * @param {string} expectedOutput
+ */
 function checkSynth(compressed, expectSuccess, expectedOutput) {
   let success = true;
   let actual;
@@ -50,7 +58,7 @@ const allTests = {
 /* GENERATED CODE START */
 
 testAllTransforms10() {
-  let compressed = [
+  const compressed = [
     0x1b, 0xfc, 0x05, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x13, 0x7c,
     0x84, 0x26, 0xf8, 0x04, 0x10, 0x4c, 0xf0, 0x89, 0x38, 0x30, 0xc1, 0x27,
@@ -257,7 +265,7 @@ testAllTransforms10() {
 },
 
 testAllTransforms4() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x40, 0x03, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x51, 0x3e,
     0x42, 0x51, 0x3e, 0x81, 0x02, 0x51, 0x3e, 0x11, 0x04, 0xa2, 0x7c, 0xe2,
@@ -453,7 +461,7 @@ testAllTransforms4() {
 },
 
 testBaseDictWord() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x03, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x41, 0x02
   ];
@@ -472,7 +480,7 @@ testBaseDictWord() {
 },
 
 testBaseDictWordFinishBlockOnRingbufferWrap() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x1f, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x9b, 0x58, 0x32,
     0x34, 0x34, 0x34, 0x34, 0x34, 0x34, 0x34, 0x34, 0x34, 0x34, 0x34, 0x34,
@@ -492,7 +500,7 @@ testBaseDictWordFinishBlockOnRingbufferWrap() {
 },
 
 testBaseDictWordTooLong() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x41, 0x02
   ];
@@ -512,7 +520,7 @@ testBaseDictWordTooLong() {
 },
 
 testBlockCountMessage() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x0b, 0x00, 0x11, 0x01, 0x8c, 0xc1, 0xc5, 0x0d, 0x08, 0x00, 0x22,
     0x65, 0xe1, 0xfc, 0xfd, 0x22, 0x2c, 0xc4, 0x00, 0x00, 0x38, 0xd8, 0x32,
     0x89, 0x01, 0x12, 0x00, 0x00, 0x77, 0xda, 0x04, 0x10, 0x42, 0x00, 0x00,
@@ -563,7 +571,7 @@ testBlockCountMessage() {
 },
 
 testBlockSwitchMessage() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x0b, 0x00, 0xd1, 0xe1, 0x01, 0xc6, 0xe0, 0xe2, 0x06, 0x04, 0x00,
     0x91, 0xb2, 0x70, 0xfe, 0x7e, 0x11, 0x16, 0x62, 0x00, 0x00, 0x1c, 0x6c,
     0x99, 0xc4, 0x00, 0x09, 0x00, 0x80, 0x3b, 0x6d, 0x02, 0x08, 0x82, 0x00,
@@ -616,7 +624,7 @@ testBlockSwitchMessage() {
 },
 
 testClClTreeDeficiency() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x03, 0x00, 0x00, 0x00, 0x01, 0x80, 0x43, 0x01, 0xe0, 0x05, 0x88,
     0x55, 0x90, 0x01, 0x00, 0x38, 0xd8, 0x32, 0x89, 0x01, 0x12, 0x00, 0x00,
     0x77, 0xda, 0x28, 0x40, 0x23
@@ -647,7 +655,7 @@ testClClTreeDeficiency() {
 },
 
 testClClTreeExcess() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x03, 0x00, 0x00, 0x00, 0x01, 0x80, 0xc3, 0x7b, 0x80, 0x58, 0x41,
     0x06, 0x00, 0xe0, 0x60, 0xcb, 0x24, 0x06, 0x48, 0x00, 0x00, 0xdc, 0x69,
     0xa3, 0x00, 0x8d, 0x00
@@ -678,7 +686,7 @@ testClClTreeExcess() {
 },
 
 testComplexHuffmanCodeTwoSymbols() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x01, 0x00, 0x00, 0x80, 0x03, 0xe0, 0xa2, 0x1a, 0x00, 0x00, 0x0e,
     0xb6, 0x4c, 0x62, 0x80, 0x04, 0x00, 0xc0, 0x9d, 0x36, 0x12, 0x04
   ];
@@ -711,7 +719,7 @@ testComplexHuffmanCodeTwoSymbols() {
 },
 
 testCompressedUncompressedShortCompressed() {
-  let compressed = [
+  const compressed = [
     0x8b, 0xfe, 0x01, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x9b, 0x66, 0x6f,
     0x1b, 0x0a, 0x50, 0x00, 0x10, 0x62, 0x62, 0x62, 0x62, 0x62, 0x62, 0x31,
@@ -748,7 +756,7 @@ testCompressedUncompressedShortCompressed() {
 },
 
 testCompressedUncompressedShortCompressedSmallWindow() {
-  let compressed = [
+  const compressed = [
     0x21, 0xf4, 0x0f, 0x00, 0x00, 0x00, 0x00, 0x1c, 0xa7, 0x6d, 0x00, 0x00,
     0x38, 0xd8, 0x32, 0x89, 0x01, 0x12, 0x00, 0x00, 0x77, 0xda, 0x34, 0x7b,
     0xdb, 0x50, 0x80, 0x02, 0x80, 0x62, 0x62, 0x62, 0x62, 0x62, 0x62, 0x31,
@@ -785,7 +793,7 @@ testCompressedUncompressedShortCompressedSmallWindow() {
 },
 
 testCopyLengthTooLong() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x01, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x11, 0x86,
     0x02
@@ -805,7 +813,7 @@ testCopyLengthTooLong() {
 },
 
 testCopyTooLong() {
-  let compressed = [
+  const compressed = [
     0xa1, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1c, 0xa7, 0x6d, 0x00, 0x00,
     0x38, 0xd8, 0x32, 0x89, 0x01, 0x12, 0x00, 0x00, 0x77, 0xda, 0x34, 0xab,
     0xdb, 0x50, 0x00
@@ -825,7 +833,7 @@ testCopyTooLong() {
 },
 
 testCustomHuffmanCode() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x03, 0x00, 0x00, 0x00, 0x01, 0x80, 0xc3, 0x3d, 0x80, 0x58, 0x82,
     0x08, 0x00, 0xc0, 0xc1, 0x96, 0x49, 0x0c, 0x90, 0x00, 0x00, 0xb8, 0xd3,
     0x46, 0x01, 0x1a, 0x01
@@ -870,7 +878,7 @@ testCustomHuffmanCode() {
 },
 
 testDistanceLut() {
-  let compressed = [
+  const compressed = [
     0x8b, 0x02, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x99, 0x86,
     0x46, 0xc6, 0x22, 0x14, 0x00, 0x00, 0x03, 0x00, 0x00, 0x1c, 0xa7, 0x6d,
@@ -906,7 +914,7 @@ testDistanceLut() {
 },
 
 testEmpty() {
-  let compressed = [
+  const compressed = [
     0x3b
   ];
   checkSynth(
@@ -921,7 +929,7 @@ testEmpty() {
 },
 
 testHelloWorld() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x0a, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x9b, 0x00, 0x59,
     0x98, 0xda, 0xd8, 0xd8, 0x13, 0xb8, 0xdb, 0x3b, 0xd9, 0x98, 0x00
@@ -938,7 +946,7 @@ testHelloWorld() {
 },
 
 testInsertTooLong() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x09, 0x86,
     0x46
@@ -958,7 +966,7 @@ testInsertTooLong() {
 },
 
 testIntactDistanceRingBuffer0() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x0a, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0xa1, 0x80,
     0x20, 0x00
@@ -979,7 +987,7 @@ testIntactDistanceRingBuffer0() {
 },
 
 testIntactDistanceRingBuffer1() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x09, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x21, 0xa0,
     0x20, 0x00
@@ -1000,7 +1008,7 @@ testIntactDistanceRingBuffer1() {
 },
 
 testIntactDistanceRingBuffer2() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x0f, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x41, 0x80,
     0x20, 0x50, 0x10, 0x24, 0x08, 0x06
@@ -1025,7 +1033,7 @@ testIntactDistanceRingBuffer2() {
 },
 
 testIntactDistanceRingBufferNoDistanceValue0() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x17, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x40, 0x82,
     0x40, 0x41, 0x90, 0x20, 0x58, 0x18, 0x00
@@ -1055,7 +1063,7 @@ testIntactDistanceRingBufferNoDistanceValue0() {
 },
 
 testIntactDistanceRingBufferNoDistanceValue1() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x19, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0xc0, 0x82,
     0x41, 0x41, 0x90, 0x20, 0x58, 0x18, 0x00
@@ -1085,7 +1093,7 @@ testIntactDistanceRingBufferNoDistanceValue1() {
 },
 
 testInvalidNoLastMetablock() {
-  let compressed = [
+  const compressed = [
     0x0b, 0x06, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x9b, 0x00, 0x13,
     0x59, 0x98, 0xda, 0xd8, 0xd8, 0x13, 0xb8, 0xdb, 0x3b, 0xd9, 0x98, 0xe8,
@@ -1103,7 +1111,7 @@ testInvalidNoLastMetablock() {
 },
 
 testInvalidNoMetaBlocks() {
-  let compressed = [
+  const compressed = [
     0x0b
   ];
   checkSynth(
@@ -1117,7 +1125,7 @@ testInvalidNoMetaBlocks() {
 },
 
 testInvalidTooFarDist() {
-  let compressed = [
+  const compressed = [
     0xa1, 0x48, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1c, 0xa7, 0x6d, 0x00, 0x00,
     0x38, 0xd8, 0x32, 0x89, 0x01, 0x12, 0x00, 0x00, 0x77, 0xda, 0xe8, 0xe0,
     0x62, 0x6f, 0x4f, 0x60, 0x66, 0xe8, 0x44, 0x38, 0x0f, 0x09, 0x0d
@@ -1139,7 +1147,7 @@ testInvalidTooFarDist() {
 },
 
 testInvalidTooLargeContextMap() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x00, 0x00, 0xd1, 0xe1, 0x01, 0xc6, 0xe0, 0xe2, 0x06, 0x00, 0x00,
     0x91, 0xb2, 0x70, 0xfe, 0xfb, 0x45, 0x58, 0x88, 0x01, 0x00, 0x70, 0xb0,
     0x65, 0x12, 0x03, 0x24, 0x00, 0x00, 0xee, 0xb4, 0x11, 0x01
@@ -1185,7 +1193,7 @@ testInvalidTooLargeContextMap() {
 },
 
 testInvalidTransformType() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x03, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x41, 0x2d,
     0x01, 0x19
@@ -1204,7 +1212,7 @@ testInvalidTransformType() {
 },
 
 testInvalidWindowBits9() {
-  let compressed = [
+  const compressed = [
     0x91, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1c, 0xa7, 0x6d, 0x00, 0x00,
     0x38, 0xd8, 0x32, 0x89, 0x01, 0x12, 0x00, 0x00, 0x77, 0xda, 0xc8, 0x20,
     0x32, 0xd4, 0x01
@@ -1221,7 +1229,7 @@ testInvalidWindowBits9() {
 },
 
 testManyTinyMetablocks() {
-  let compressed = [
+  const compressed = [
     0x0b, 0x00, 0x80, 0x61, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x38, 0x4e,
     0xdb, 0x00, 0x00, 0x70, 0xb0, 0x65, 0x12, 0x03, 0x24, 0x00, 0x00, 0xee,
     0xb4, 0x11, 0x61, 0x04, 0x00, 0x80, 0x61, 0x00, 0x00, 0x00, 0x00, 0x00,
@@ -1923,7 +1931,7 @@ testManyTinyMetablocks() {
 },
 
 testNegativeDistance() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x0f, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x41, 0x02,
     0x01, 0x42, 0x01, 0x42, 0x01, 0x42, 0x01, 0x42, 0x01, 0x42, 0x01, 0x1c
@@ -1954,7 +1962,7 @@ testNegativeDistance() {
 },
 
 testNegativeRemainingLenBetweenMetablocks() {
-  let compressed = [
+  const compressed = [
     0x0b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x09, 0x86,
     0x46, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x38, 0x4e, 0xdb, 0x00, 0x00,
@@ -1976,7 +1984,7 @@ testNegativeRemainingLenBetweenMetablocks() {
 },
 
 testOneCommand() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x02, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x11, 0x86,
     0x02
@@ -1995,7 +2003,7 @@ testOneCommand() {
 },
 
 testOneInsert() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x01, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x09, 0x86,
     0x46
@@ -2014,7 +2022,7 @@ testOneInsert() {
 },
 
 testSimplePrefix() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x03, 0x00, 0x00, 0xa0, 0xc3, 0xc4, 0xc6, 0xc8, 0x02, 0x00, 0x70,
     0xb0, 0x65, 0x12, 0x03, 0x24, 0x00, 0x00, 0xee, 0xb4, 0x51, 0xa0, 0x1d
   ];
@@ -2036,7 +2044,7 @@ testSimplePrefix() {
 },
 
 testSimplePrefixDuplicateSymbols() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x03, 0x00, 0x00, 0xa0, 0xc3, 0xc4, 0xc2, 0xc4, 0x02, 0x00, 0x70,
     0xb0, 0x65, 0x12, 0x03, 0x24, 0x00, 0x00, 0xee, 0xb4, 0x51, 0xa0, 0x1d
   ];
@@ -2058,7 +2066,7 @@ testSimplePrefixDuplicateSymbols() {
 },
 
 testSimplePrefixOutOfRangeSymbols() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x03, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x4d, 0xff, 0xef,
     0x7f, 0xff, 0xfc, 0x07, 0x00, 0xb8, 0xd3, 0x06
   ];
@@ -2080,7 +2088,7 @@ testSimplePrefixOutOfRangeSymbols() {
 testSimplePrefixPlusExtraData() {
   // SKIP: JS decoder does not tolerate extra input after the brotli stream.
   if ({}.toString() == {}) return;  // same as 'if (true) return'
-  let compressed = [
+  const compressed = [
     0x1b, 0x03, 0x00, 0x00, 0xa0, 0xc3, 0xc4, 0xc6, 0xc8, 0x02, 0x00, 0x70,
     0xb0, 0x65, 0x12, 0x03, 0x24, 0x00, 0x00, 0xee, 0xb4, 0x51, 0xa0, 0x1d,
     0x55, 0xaa
@@ -2105,7 +2113,7 @@ testSimplePrefixPlusExtraData() {
 },
 
 testStressReadDistanceExtraBits() {
-  let compressed = [
+  const compressed = [
     0x4f, 0xfe, 0xff, 0x3f, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00,
     0x00, 0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x9b, 0xf6,
     0x69, 0xef, 0xff, 0x0c, 0x8d, 0x8c, 0x05, 0x10, 0x00, 0x00, 0x00, 0x00,
@@ -2119,7 +2127,7 @@ testStressReadDistanceExtraBits() {
     0x46, 0x03
   ];
   /* This line is added manually. */
-  let stub = repeat("c", 8388602); let hex = "0123456789ABCDEF";
+  const stub = repeat("c", 8388602); const hex = "0123456789ABCDEF";
   checkSynth(
     /*
      * main_header: 24
@@ -2178,7 +2186,7 @@ testStressReadDistanceExtraBits() {
 },
 
 testTooManySymbolsRepeated() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x03, 0x00, 0x00, 0x00, 0x01, 0x80, 0xc3, 0x3d, 0x80, 0x58, 0x82,
     0x0c, 0x00, 0xc0, 0xc1, 0x96, 0x49, 0x0c, 0x90, 0x00, 0x00, 0xb8, 0xd3,
     0x46, 0x01, 0x1a, 0x01
@@ -2209,7 +2217,7 @@ testTooManySymbolsRepeated() {
 },
 
 testTransformedDictWord() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x41, 0x09,
     0x01, 0x01
@@ -2229,7 +2237,7 @@ testTransformedDictWord() {
 },
 
 testTransformedDictWordTooLong() {
-  let compressed = [
+  const compressed = [
     0x1b, 0x03, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe3, 0xb4, 0x0d, 0x00, 0x00,
     0x07, 0x5b, 0x26, 0x31, 0x40, 0x02, 0x00, 0xe0, 0x4e, 0x1b, 0x41, 0x09,
     0x01, 0x01
@@ -2251,12 +2259,12 @@ testTransformedDictWordTooLong() {
 },
 
 testZeroCostLiterals() {
-  let compressed = [
+  const compressed = [
     0x9b, 0xff, 0xff, 0xff, 0x00, 0x20, 0x54, 0x00, 0x00, 0x38, 0xd8, 0x32,
     0x89, 0x01, 0x12, 0x00, 0x00, 0x77, 0xda, 0xcc, 0xe1, 0x7b, 0xfa, 0x0f
   ];
   /* This line is added manually. */
-  let expected = repeat("*", 16777216);
+  const expected = repeat("*", 16777216);
   checkSynth(
     /*
      * main_header

js/decode_test.ts

@@ -0,0 +1,38 @@
+/* Copyright 2023 Google Inc. All Rights Reserved.
+
+   Distributed under MIT license.
+   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+
+import 'jasmine';
+
+import {brotliDecode} from './decode';
+
+function bytesToString(bytes: Int8Array): string {
+  const chars: number[] = new Uint16Array(bytes) as unknown as number[];
+  return String.fromCharCode.apply(null, chars);
+}
+
+function stringToBytes(str: string): Int8Array {
+  const out = new Int8Array(str.length);
+  for (let i = 0; i < str.length; ++i) out[i] = str.charCodeAt(i);
+  return out;
+}
+
+describe('DecodeTest', () => {
+  it('testMetadata', () => {
+    expect('').toEqual(
+        bytesToString(brotliDecode(Int8Array.from([1, 11, 0, 42, 3]))));
+  });
+
+  it('testCompoundDictionary', () => {
+    const txt = 'kot lomom kolol slona\n';
+    const dictionary = stringToBytes(txt);
+    const compressed =
+        [0xa1, 0xa8, 0x00, 0xc0, 0x2f, 0x01, 0x10, 0xc4, 0x44, 0x09, 0x00];
+    expect(txt.length).toEqual(compressed.length * 2);
+    const options = {'customDictionary': dictionary};
+    expect(txt).toEqual(
+        bytesToString(brotliDecode(Int8Array.from(compressed), options)));
+  });
+});