Alter URL encoding

test/checkbox-tree.test.js

@@ -13,6 +13,8 @@ const {
     base64UrlToBytes,
     bytesToBase64Url,
     decodeTreeState,
+    decodeAdaptiveBitset,
+    encodeAdaptiveBitset,
     getBit,
     loadManifest,
     setBit,
@@ -136,6 +138,28 @@ test('Base64URL encoding is unpadded, URL-safe, and round trips', () => {
     assert.throws(() => base64UrlToBytes('not valid!'), /Invalid Base64URL/);
 });
 
+test('adaptive bitsets choose sparse enabled and disabled representations', () => {
+    const mostlyDisabled = new Map(Array.from(
+        { length: 628 },
+        (_, slot) => [slot, slot === 2 || slot === 400]
+    ));
+    const sparseEnabled = encodeAdaptiveBitset(mostlyDisabled, 628);
+    assert.equal(sparseEnabled[0], 1);
+    const enabled = decodeAdaptiveBitset(sparseEnabled, 628);
+    assert.equal(enabled(2), true);
+    assert.equal(enabled(3), false);
+    assert.equal(enabled(400), true);
+
+    const nearlyAllEnabled = new Map(Array.from({ length: 100 }, (_, slot) => [slot, slot !== 7]));
+    const sparseDisabled = encodeAdaptiveBitset(nearlyAllEnabled, 100);
+    assert.equal(sparseDisabled[0], 2);
+    const enabledExcept = decodeAdaptiveBitset(sparseDisabled, 105);
+    assert.equal(enabledExcept(6), true);
+    assert.equal(enabledExcept(7), false);
+    assert.equal(enabledExcept(99), true);
+    assert.equal(enabledExcept(100), false);
+});
+
 test('loads text and JSON manifests while retaining tombstone slots', () => {
     const text = loadManifest('# tree-state-manifest\nroot\n!deleted\nroot>child\n');
     assert.equal(text.slots.length, 3);
@@ -170,7 +194,7 @@ test('serializes and restores checked and expanded state through a fragment', ()
     checkbox(first.container, 'first').click();
     first.container.querySelector('.checkbox-tree__toggle').click();
     const fragment = first.tree.serializeStateToFragment(manifest);
-    assert.equal(fragment, '#v=1&c=Ag&x=AQ');
+    assert.equal(fragment, '#v=1&c=AAI&x=AAE');
 
     const second = createTree({ manifest });
     const result = second.tree.restoreStateFromLocation(manifest, { hash: fragment });
@@ -201,7 +225,7 @@ test('malformed, oversized, and unsupported URL state fails safely', () => {
     const manifest = loadManifest({ schema: 1, nodes: ['parent', 'parent>first', 'parent>second'] });
     assert.equal(decodeTreeState('#v=2&c=AQ', manifest).applied, false);
     assert.equal(decodeTreeState('#v=1&c=!', manifest).applied, false);
-    assert.equal(decodeTreeState('#v=1&c=AQA', manifest).applied, false);
+    assert.equal(decodeTreeState('#v=1&c=Aw', manifest).applied, false);
 
     const { tree } = createTree({ initiallySelected: true });
     const result = tree.restoreStateFromLocation(manifest, { hash: '#v=1&c=!' });