fix: preserve Set/Map order when restoring referential equalities

src/accessDeep.ts

@@ -106,11 +106,14 @@ export const setDeep = (
   }
 
   if (isSet(parent)) {
-    const oldValue = getNthKey(parent, +lastKey);
+    const index = +lastKey;
+    const oldValue = getNthKey(parent, index);
     const newValue = mapper(oldValue);
     if (oldValue !== newValue) {
-      parent.delete(oldValue);
-      parent.add(newValue);
+      const values = [...parent];
+      values[index] = newValue;
+      parent.clear();
+      values.forEach(value => parent.add(value));
     }
   }
 
@@ -122,10 +125,12 @@ export const setDeep = (
     switch (type) {
       case 'key': {
         const newKey = mapper(keyToRow);
-        parent.set(newKey, parent.get(keyToRow));
-
         if (newKey !== keyToRow) {
-          parent.delete(keyToRow);
+          const entries = [...parent];
+          parent.clear();
+          entries.forEach(([k, v]) =>
+            parent.set(k === keyToRow ? newKey : k, v)
+          );
         }
         break;
       }

src/index.test.ts

@@ -1313,6 +1313,43 @@ test('regression #245: superjson referential equalities only use the top-most pa
   expect(parsed).toEqual(input);
 });
 
+test('restores multiple referentially equal values inside the same Set', () => {
+  const a = { tag: 'a' };
+  const b = { tag: 'b' };
+  const input = {
+    set: new Set([a, b]),
+    a,
+    b,
+  };
+
+  const output: any = SuperJSON.deserialize(SuperJSON.serialize(input));
+
+  expect([...output.set]).toEqual([a, b]);
+  expect(output.set.has(output.a)).toBe(true);
+  expect(output.set.has(output.b)).toBe(true);
+  expect([...output.set][0]).toBe(output.a);
+  expect([...output.set][1]).toBe(output.b);
+});
+
+test('restores multiple referentially equal keys inside the same Map', () => {
+  const a = { tag: 'a' };
+  const b = { tag: 'b' };
+  const input = {
+    map: new Map<any, any>([
+      [a, 1],
+      [b, 2],
+    ]),
+    a,
+    b,
+  };
+
+  const output: any = SuperJSON.deserialize(SuperJSON.serialize(input));
+
+  expect([...output.map.keys()]).toEqual([a, b]);
+  expect(output.map.get(output.a)).toBe(1);
+  expect(output.map.get(output.b)).toBe(2);
+});
+
 test('dedupe=true', () => {
   const instance = new SuperJSON({
     dedupe: true,