Break potential infinite loop

packages/red-black-tree/package.json

@@ -34,7 +34,7 @@
     "ava": "^0.24.0",
     "rimraf": "^2.6.2",
     "tslint": "^5.9.1",
-    "typescript": "^2.6.2"
+    "typescript": "3.5.1"
   },
   "ava": {
     "files": [

packages/red-black-tree/src/internals/path.ts

@@ -67,6 +67,7 @@ export class PathNode<K, V> {
   release (): PathNode<K, V> {
     var p = this.parent;
     this.node = NONE;
+    this.next = BRANCH.NONE;
     this.parent = PathNode.cache;
     PathNode.cache = this;
     return p;

packages/red-black-tree/tests/internals/rebalance.ts

@@ -0,0 +1,77 @@
+import test from 'ava';
+import { empty, set } from '../../src';
+import { RedBlackTreeStructure, isNone } from '../../src/internals';
+
+let tree: RedBlackTreeStructure<string, User>;
+
+type User = {
+  name: string,
+  id: string
+};
+
+const testUser1: User = {
+    name: 'Luke',
+    id: '298'
+};
+
+const testUser2: User = {
+    name: 'Leia',
+    id: '299'
+};
+
+const testUser3: User = {
+  name: 'Han',
+  id: '300'
+};
+
+const testUser4: User = {
+  name: 'Chewbacca',
+  id: '301'
+};
+
+test.beforeEach(() => {
+  tree = empty<string, User>((a, b) => a < b ? -1 : (a > b ? 1 : 0), true);
+});
+
+test('should keep the tree balanced', t => {
+  t.plan(13);
+
+  // Set 298 and make sure it's the root and no other elements are there
+  tree = set(testUser1.id, testUser1, tree);
+  t.is(tree._root.key, testUser1.id);
+  t.is(isNone(tree._root._left), true);
+  t.is(isNone(tree._root._right), true);
+
+  // Set 299, no rebalance. 299 should be on the right
+  tree = set(testUser2.id, testUser2, tree);
+  t.is(tree._root.key, testUser1.id);
+  t.is(isNone(tree._root._left), true);
+  t.is(tree._root._right.key, testUser2.id);
+
+  // Set 300, this should cause a rebalance that puts 299 at the top
+  tree = set(testUser3.id, testUser3, tree);
+  t.is(tree._root.key, testUser2.id); // 299 is root
+  t.is(tree._root._left.key, testUser1.id); // 298 goes left
+  t.is(tree._root._right.key, testUser3.id); // 300 goes right
+
+  // Set 301, no rebalance - will go on the right of 300
+  tree = set(testUser4.id, testUser4, tree);
+  t.is(tree._root.key, testUser2.id); // 299 is root
+  t.is(tree._root._left.key, testUser1.id); // 298 goes left
+  t.is(tree._root._right.key, testUser3.id); // 300 goes right
+  t.is(tree._root._right._right.key, testUser4.id); // 300 goes right
+});
+
+test('should keep the tree balanced - many items synchronously', t => {
+  // Add accounts to the tree which will trigger lots of rebalancing
+  for (let i = 0; i < 1000; i++) {
+    const user: User = {
+      name: i.toString(),
+      id: i.toString()
+    };
+    tree = set(user.id, user, tree);
+  }
+
+  t.is(tree._root.key, '487');
+  t.is(tree._size, 1000);
+});