Change snapshot tests to compare decompressed bitstreams

The snapshots are compressed differently in Node.js 21. The compression has been stable for many versions but that is not a guarantee, see nodejs/node#50138 for background.

Change tests to compare the decompressed data instead.

lib/snapshot-manager.js

@@ -198,7 +198,7 @@ async function encodeSnapshots(snapshotData) {
 	], READABLE_PREFIX.byteLength + VERSION_HEADER.byteLength + SHA_256_HASH_LENGTH + compressed.byteLength);
 }
 
-function decodeSnapshots(buffer, snapPath) {
+export function extractCompressedSnapshot(buffer, snapPath) {
 	if (isLegacySnapshot(buffer)) {
 		throw new LegacyError(snapPath);
 	}
@@ -220,6 +220,12 @@ function decodeSnapshots(buffer, snapPath) {
 	const compressedOffset = sha256sumOffset + SHA_256_HASH_LENGTH;
 	const compressed = buffer.slice(compressedOffset);
 
+	return {version, compressed, sha256sumOffset, compressedOffset};
+}
+
+function decodeSnapshots(buffer, snapPath) {
+	const {compressed, sha256sumOffset, compressedOffset} = extractCompressedSnapshot(buffer, snapPath);
+
 	const sha256sum = crypto.createHash('sha256').update(compressed).digest();
 	const expectedSum = buffer.slice(sha256sumOffset, compressedOffset);
 	if (!sha256sum.equals(expectedSum)) {

test-tap/integration/snapshots.js

@@ -2,11 +2,13 @@ import {Buffer} from 'node:buffer';
 import fs from 'node:fs';
 import path from 'node:path';
 import {fileURLToPath} from 'node:url';
+import {gunzipSync} from 'node:zlib';
 
 import {execa} from 'execa';
 import {test} from 'tap';
 import {temporaryDirectory} from 'tempy';
 
+import {extractCompressedSnapshot} from '../../lib/snapshot-manager.js';
 import {execCli} from '../helper/cli.js';
 
 const __dirname = fileURLToPath(new URL('.', import.meta.url));
@@ -265,9 +267,9 @@ test('snapshots are identical on different platforms', t => {
 		t.ok(fs.existsSync(snapPath));
 
 		const reportContents = fs.readFileSync(reportPath);
-		const snapContents = fs.readFileSync(snapPath);
+		const snapContents = gunzipSync(extractCompressedSnapshot(fs.readFileSync(snapPath)).compressed);
 		const expectedReportContents = fs.readFileSync(expectedReportPath);
-		const expectedSnapContents = fs.readFileSync(expectedSnapPath);
+		const expectedSnapContents = gunzipSync(extractCompressedSnapshot(fs.readFileSync(expectedSnapPath)).compressed);
 
 		t.ok(reportContents.equals(expectedReportContents), 'report file contents matches snapshot');
 		t.ok(snapContents.equals(expectedSnapContents), 'snap file contents matches snapshot');

test/snapshot-order/randomness.js

@@ -1,8 +1,10 @@
 import fs from 'node:fs';
 import path from 'node:path';
+import {gunzipSync} from 'node:zlib';
 
 import test from '@ava/test';
 
+import {extractCompressedSnapshot} from '../../lib/snapshot-manager.js';
 import {cwd, fixture} from '../helpers/exec.js';
 
 import getSnapshotIds from './helpers/get-snapshot-ids.js';
@@ -23,8 +25,9 @@ test('deterministic and sorted over a large, random test case', async t => {
 
 	// Assert snapshot is unchanged
 	const snapshot = fs.readFileSync(snapshotPath);
+	const {compressed} = extractCompressedSnapshot(snapshot, snapshotPath);
 
-	t.snapshot(snapshot, 'resulting snapshot in binary encoding');
+	t.snapshot(gunzipSync(compressed), 'resulting snapshot in binary encoding');
 
 	// Assert report is sorted
 	const report = fs.readFileSync(reportPath);

test/snapshot-order/snapshots/randomness.js.md

@@ -9,14 +9,26 @@ Generated by [AVA](https://avajs.dev).
 > resulting snapshot in binary encoding
 
     Buffer @Uint8Array [
-      41564120 536e6170 73686f74 2076330a 03008ba7 6ff7a1a2 251e5fa1 afbf3fa8
-      fdf7ca69 3e5b2af2 b0734c95 46791417 ae201f8b 08000000 00000003 5b989694
-      939f9c5d dcba28b5 24b32427 b542ca49 41572125 353927b1 2855a138 3f1748e4
-      25161467 e4971467 c259cd0b 5352124b 12c39819 d8194080 91954190 9123332f
-      25b5c24a c160111e 49c3d49c c4a4d49c dc8cc462 854485dc d4e2e2c4 f4547c1a
-      8c201a8a 12738af3 15507541 5d2cef88 eee2dcfc 22acce6e c4e76c13 9879aace
-      38434021 330f687f 4951a586 265260e0 73be29c4 f9a9f9a5 25a945f8 149a4115
-      66e6e5e1 57680e51 980d3651 21313d31 330fee72 5790cb33 8b93138b 52887179
-      133e7b2c 305d1e8e a2901316 a506385d 54e40274 10aed868 5a88cf50 23bcb2c6
-      00d6e9f1 35b80200 00
+      a166626c 6f636b73 85a26574 69746c65 781a4220 2d206465 636c6172 6520736f
+      6d652073 6e617073 686f7473 69736e61 7073686f 747383a1 64646174 61560300
+      07000000 00000105 00110108 696e6465 783a2030 a2646461 74615603 00070000
+      00000001 05001101 08696e64 65783a20 31656c61 62656c6d 68617320 61206d65
+      73736167 65a26464 61746156 03000700 00000000 01050011 0108696e 6465783a
+      2032656c 6162656c 72616c73 6f206861 73206120 6d657373 616765a2 65746974
+      6c65781f 41202d20 6465636c 61726520 736f6d65 206d6f72 6520736e 61707368
+      6f747369 736e6170 73686f74 7381a164 64617461 56030007 00000000 00010500
+      11010869 6e646578 3a2034a2 65746974 6c657825 43202d20 6465636c 61726520
+      736f6d65 20736e61 7073686f 74732069 6e206120 74727928 2969736e 61707368
+      6f747383 a2646461 74615603 00070000 00000001 05001101 08696e64 65783a20
+      35656c61 62656c65 6f757465 72a26464 61746156 03000700 00000000 01050011
+      0108696e 6465783a 2036656c 6162656c 65696e6e 6572a264 64617461 56030007
+      00000000 00010500 11010869 6e646578 3a203765 6c616265 6c6b6f75 74657220
+      61676169 6ea26574 69746c65 78254520 2d206469 73636172 6420736f 6d652073
+      6e617073 686f7473 20696e20 61207472 79282969 736e6170 73686f74 7382a264
+      64617461 56030007 00000000 00010500 11010869 6e646578 3a203865 6c616265
+      6c656f75 746572a2 64646174 61570300 07000000 00000105 00110109 696e6465
+      783a2031 30656c61 62656c6b 6f757465 72206167 61696ea2 65746974 6c657244
+      202d206d 6f726520 736e6170 73686f74 7369736e 61707368 6f747382 a1646461
+      74615703 00070000 00000001 05001101 09696e64 65783a20 3132a164 64617461
+      57030007 00000000 00010500 11010969 6e646578 3a203133
     ]

test/snapshot-workflow/helpers/macros.js

@@ -1,9 +1,11 @@
 
 import {promises as fs} from 'node:fs';
 import path from 'node:path';
+import {gunzipSync} from 'node:zlib';
 
 import concordance from 'concordance';
 
+import {extractCompressedSnapshot} from '../../../lib/snapshot-manager.js';
 import {fixture} from '../../helpers/exec.js';
 import {withTemporaryFixture} from '../../helpers/with-temporary-fixture.js';
 
@@ -63,9 +65,12 @@ export async function beforeAndAfter(t, {
 }
 
 async function readSnapshots(cwd) {
+	const snapPath = path.join(cwd, 'test.js.snap');
 	const [snapshot, report] = await Promise.all([
-		fs.readFile(path.join(cwd, 'test.js.snap')),
+		fs.readFile(snapPath),
 		fs.readFile(path.join(cwd, 'test.js.md'), 'utf8'),
 	]);
-	return {snapshot, report};
+
+	const {version, compressed} = extractCompressedSnapshot(snapshot, snapPath);
+	return {snapshot: {version, decompressed: gunzipSync(compressed)}, report};
 }