Initial import of verae-tree-node from zapier monorepo

test/merkle.test.js

@@ -0,0 +1,34 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import {
+  sha256Hex,
+  buildMerkle,
+  merkleProof,
+  verifyProof,
+  shardIndex,
+} from '../src/merkle.js';
+
+describe('merkle', () => {
+  it('one leaf is its own root', () => {
+    const leaf = sha256Hex('only');
+    const t = buildMerkle([leaf]);
+    assert.equal(t.root, leaf);
+    assert.equal(verifyProof(leaf, merkleProof(t.layers, 0), t.root), true);
+  });
+
+  it('three leaves: each proof verifies, unknown leaf does not', () => {
+    const leaves = ['a', 'b', 'c'].map((s) => sha256Hex(s));
+    const t = buildMerkle(leaves);
+    for (let i = 0; i < leaves.length; i += 1) {
+      const proof = merkleProof(t.layers, i);
+      assert.equal(verifyProof(leaves[i], proof, t.root), true);
+    }
+    assert.equal(verifyProof(sha256Hex('nope'), merkleProof(t.layers, 0), t.root), false);
+  });
+
+  it('shards stably into three nodes', () => {
+    const h = sha256Hex('x');
+    assert.equal(shardIndex(h, 3), shardIndex(h, 3));
+    assert.ok(shardIndex(h, 3) >= 0 && shardIndex(h, 3) < 3);
+  });
+});