test_runner: remove unused shuffleArrayWithSeed

watilde · aduh95 · commit 9485caa97eec · 2026-06-18T10:10:52.000+02:00
shuffleArrayWithSeed was introduced along with test order randomization but was never called: the feature picks a random pending subtest at dequeue time using createSeededGenerator directly. Remove the dead helper and its export, and add direct unit coverage for createSeededGenerator's deterministic contract. Signed-off-by: Daijiro Wachi <daijiro.wachi@gmail.com> PR-URL: #63847 Reviewed-By: Chemi Atlow <chemi@atlow.co.il> Reviewed-By: Jacob Smith <jacob@frende.me> Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
diff --git a/lib/internal/test_runner/utils.js b/lib/internal/test_runner/utils.js
@@ -7,7 +7,6 @@ const {
   ArrayPrototypePop,
   ArrayPrototypePush,
   ArrayPrototypeReduce,
-  ArrayPrototypeSlice,
   ArrayPrototypeSome,
   JSONParse,
   MathFloor,
@@ -166,31 +165,6 @@ function createSeededGenerator(seed) {
   };
 }
 
-/**
- * Return a deterministically shuffled copy of an array.
- * @template T
- * @param {T[]} values
- * @param {number} seed
- * @returns {T[]}
- */
-function shuffleArrayWithSeed(values, seed) {
-  if (values.length < 2) {
-    return values;
-  }
-
-  const randomized = ArrayPrototypeSlice(values);
-  const random = createSeededGenerator(seed);
-
-  for (let i = randomized.length - 1; i > 0; i--) {
-    const j = MathFloor(random() * (i + 1));
-    const tmp = randomized[i];
-    randomized[i] = randomized[j];
-    randomized[j] = tmp;
-  }
-
-  return randomized;
-}
-
 function tryBuiltinReporter(name) {
   const builtinPath = kBuiltinReporters.get(name);
 
@@ -761,7 +735,6 @@ module.exports = {
   kDefaultPattern,
   kMaxRandomSeed,
   parseCommandLine,
-  shuffleArrayWithSeed,
   reporterScope,
   shouldColorizeTestFiles,
   getCoverageReport,
diff --git a/test/parallel/test-runner-seeded-generator.js b/test/parallel/test-runner-seeded-generator.js
@@ -0,0 +1,33 @@
+// Flags: --expose-internals
+'use strict';
+require('../common');
+const assert = require('node:assert');
+const { createSeededGenerator, kMaxRandomSeed } = require('internal/test_runner/utils');
+
+function sequence(seed, length = 10) {
+  const random = createSeededGenerator(seed);
+  const values = [];
+  for (let i = 0; i < length; i++) {
+    values.push(random());
+  }
+  return values;
+}
+
+// The same seed must always produce the same sequence so that
+// --test-random-seed reproduces a randomized test order across runs.
+assert.deepStrictEqual(sequence(0), sequence(0));
+assert.deepStrictEqual(sequence(12345), sequence(12345));
+assert.deepStrictEqual(sequence(kMaxRandomSeed), sequence(kMaxRandomSeed));
+
+// Different seeds must produce different sequences.
+assert.notDeepStrictEqual(sequence(11111), sequence(22222));
+assert.notDeepStrictEqual(sequence(0), sequence(1));
+
+// Seeds are coerced to uint32, matching the range accepted by
+// --test-random-seed.
+assert.deepStrictEqual(sequence(1), sequence(1 + 2 ** 32));
+
+// All generated values must fall in [0, 1).
+for (const value of sequence(98765, 1000)) {
+  assert.ok(value >= 0 && value < 1, `value ${value} out of range`);
+}
