adamshone
diff --git a/‎__tests__/Set.ts
Copy file name to clipboardExpand all lines: __tests__/Set.ts
+39-1Lines changed: 39 additions & 1 deletion b/‎__tests__/Set.ts
Copy file name to clipboardExpand all lines: __tests__/Set.ts
+39-1Lines changed: 39 additions & 1 deletion
diff --git a/‎src/List.js
Copy file name to clipboardExpand all lines: src/List.js
+4-3Lines changed: 4 additions & 3 deletions b/‎src/List.js
Copy file name to clipboardExpand all lines: src/List.js
+4-3Lines changed: 4 additions & 3 deletions
diff --git a/‎src/Map.js
Copy file name to clipboardExpand all lines: src/Map.js
+2-4Lines changed: 2 additions & 4 deletions b/‎src/Map.js
Copy file name to clipboardExpand all lines: src/Map.js
+2-4Lines changed: 2 additions & 4 deletions
diff --git a/‎src/TrieUtils.js
Copy file name to clipboardExpand all lines: src/TrieUtils.js
+5-7Lines changed: 5 additions & 7 deletions b/‎src/TrieUtils.js
Copy file name to clipboardExpand all lines: src/TrieUtils.js
+5-7Lines changed: 5 additions & 7 deletions
@@ -8,7 +8,7 @@
 ///<reference path='../resources/jest.d.ts'/>
 
 declare var Symbol: any;
-import { is, List, Map, OrderedSet, Seq, Set } from '../';
+import { fromJS, is, List, Map, OrderedSet, Seq, Set } from '../';
 
 describe('Set', () => {
   it('accepts array of values', () => {
@@ -304,4 +304,42 @@ describe('Set', () => {
     expect(set.count(x => x % 2 === 0)).toEqual(2);
     expect(set.count(x => true)).toEqual(5);
   });
+
+  describe('"size" should correctly reflect the number of elements in a Set', () => {
+    describe('deduplicating custom classes that invoke fromJS() as part of equality check', () => {
+      class Entity {
+        constructor(entityId, entityKey) {
+          this.entityId = entityId;
+          this.entityKey = entityKey;
+        }
+        asImmutable() {
+          return fromJS({
+            entityId: this.entityId,
+            entityKey: this.entityKey,
+          });
+        }
+        valueOf() {
+          return this.asImmutable().toString();
+        }
+      }
+      it('with mutations', () => {
+        const testSet = Set().withMutations(mutableSet => {
+          mutableSet.add(new Entity('hello', 'world'));
+          mutableSet.add(new Entity('testing', 'immutable'));
+          mutableSet.add(new Entity('hello', 'world'));
+        });
+        expect(testSet.size).toEqual(2);
+      });
+      it('without mutations', () => {
+        const testSet0 = Set();
+        const testSet1 = testSet0.add(new Entity('hello', 'world'));
+        const testSet2 = testSet1.add(new Entity('testing', 'immutable'));
+        const testSet3 = testSet2.add(new Entity('hello', 'world'));
+        expect(testSet0.size).toEqual(0);
+        expect(testSet1.size).toEqual(1);
+        expect(testSet2.size).toEqual(2);
+        expect(testSet3.size).toEqual(2);
+      });
+    });
+  });
 });
@@ -10,7 +10,6 @@ import {
   SHIFT,
   SIZE,
   MASK,
-  DID_ALTER,
   OwnerID,
   MakeRef,
   SetRef,
@@ -441,7 +440,7 @@ function updateList(list, index, value) {
 
   let newTail = list._tail;
   let newRoot = list._root;
-  const didAlter = MakeRef(DID_ALTER);
+  const didAlter = MakeRef();
   if (index >= getTailOffset(list._capacity)) {
     newTail = updateVNode(newTail, list.__ownerID, 0, index, value, didAlter);
   } else {
@@ -500,7 +499,9 @@ function updateVNode(node, ownerID, level, index, value, didAlter) {
     return node;
   }
 
-  SetRef(didAlter);
+  if (didAlter) {
+    SetRef(didAlter);
+  }
 
   newNode = editableVNode(node, ownerID);
   if (value === undefined && idx === newNode.array.length - 1) {
 
@@ -14,8 +14,6 @@ import {
   SIZE,
   MASK,
   NOT_SET,
-  CHANGE_LENGTH,
-  DID_ALTER,
   OwnerID,
   MakeRef,
   SetRef,
@@ -656,8 +654,8 @@ function updateMap(map, k, v) {
     newSize = 1;
     newRoot = new ArrayMapNode(map.__ownerID, [[k, v]]);
   } else {
-    const didChangeSize = MakeRef(CHANGE_LENGTH);
-    const didAlter = MakeRef(DID_ALTER);
+    const didChangeSize = MakeRef();
+    const didAlter = MakeRef();
     newRoot = updateNode(
       map._root,
       map.__ownerID,
 
@@ -18,16 +18,14 @@ export const MASK = SIZE - 1;
 export const NOT_SET = {};
 
 // Boolean references, Rough equivalent of `bool &`.
-export const CHANGE_LENGTH = { value: false };
-export const DID_ALTER = { value: false };
-
-export function MakeRef(ref) {
-  ref.value = false;
-  return ref;
+export function MakeRef() {
+  return { value: false };
 }
 
 export function SetRef(ref) {
-  ref && (ref.value = true);
+  if (ref) {
+    ref.value = true;
+  }
 }
 
 // A function which returns a value representing an "owner" for transient writes