1 files changed, 74 insertions, 0 deletions
diff --git a/dom/webgpu/tests/cts/checkout/src/unittests/prng.spec.ts b/dom/webgpu/tests/cts/checkout/src/unittests/prng.spec.ts
new file mode 100644
index 0000000000..6317a98eea
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+++ b/dom/webgpu/tests/cts/checkout/src/unittests/prng.spec.ts
@@ -0,0 +1,74 @@
+export const description = `
+Unittests for the pseudo random number generator
+`;
+
+import { makeTestGroup } from '../common/framework/test_group.js';
+import { fullU32Range } from '../webgpu/util/math.js';
+import { PRNG } from '../webgpu/util/prng.js';
+
+import { UnitTest } from './unit_test.js';
+
+export const g = makeTestGroup(UnitTest);
+
+// There exist more formal tests for the quality of random number generators
+// that are out of the scope for testing here (and are checked against the
+// original C implementation).
+// These tests are just intended to be smoke tests for implementation.
+
+// Test against the reference u32 values from the original C implementation
+// https://github.com/MersenneTwister-Lab/TinyMT/blob/master/tinymt/check32.out.txt
+g.test('check').fn(t => {
+  const p = new PRNG(1);
+  // prettier-ignore
+  const expected = [
+    2545341989, 981918433,  3715302833, 2387538352, 3591001365,
+    3820442102, 2114400566, 2196103051, 2783359912, 764534509,
+    643179475,  1822416315, 881558334,  4207026366, 3690273640,
+    3240535687, 2921447122, 3984931427, 4092394160, 44209675,
+    2188315343, 2908663843, 1834519336, 3774670961, 3019990707,
+    4065554902, 1239765502, 4035716197, 3412127188, 552822483,
+    161364450,  353727785,  140085994,  149132008,  2547770827,
+    4064042525, 4078297538, 2057335507, 622384752,  2041665899,
+    2193913817, 1080849512, 33160901,  662956935,   642999063,
+    3384709977, 1723175122, 3866752252, 521822317,  2292524454,
+  ];
+  expected.forEach((_, i) => {
+    const val = p.randomU32();
+    t.expect(
+      val === expected[i],
+      `PRNG(1) failed produced the ${i}th expected item, ${val} instead of ${expected[i]})`
+    );
+  });
+});
+
+// Prove that generator is deterministic for at least 1000 values with different
+// seeds.
+g.test('deterministic_random').fn(t => {
+  fullU32Range().forEach(seed => {
+    const lhs = new PRNG(seed);
+    const rhs = new PRNG(seed);
+    for (let i = 0; i < 1000; i++) {
+      const lhs_val = lhs.random();
+      const rhs_val = rhs.random();
+      t.expect(
+        lhs_val === rhs_val,
+        `For seed ${seed}, the ${i}th item, PRNG was non-deterministic (${lhs_val} vs ${rhs_val})`
+      );
+    }
+  });
+});
+
+g.test('deterministic_randomU32').fn(t => {
+  fullU32Range().forEach(seed => {
+    const lhs = new PRNG(seed);
+    const rhs = new PRNG(seed);
+    for (let i = 0; i < 1000; i++) {
+      const lhs_val = lhs.randomU32();
+      const rhs_val = rhs.randomU32();
+      t.expect(
+        lhs_val === rhs_val,
+        `For seed ${seed}, the ${i}th item, PRNG was non-deterministic (${lhs_val} vs ${rhs_val})`
+      );
+    }
+  });
+});