fix and test subscription and initial values for sort

src/observable/BaseObservableCollection.js

@@ -13,13 +13,13 @@ export default class BaseObservableCollection {
 
     subscribe(handler) {
         this._handlers.add(handler);
-        if (this._handlers.length === 1) {
+        if (this._handlers.size === 1) {
             this.onSubscribeFirst();
         }
         return () => {
             if (handler) {
                 this._handlers.delete(this._handler);
-                if (this._handlers.length === 0) {
+                if (this._handlers.size === 0) {
                     this.onUnsubscribeLast();
                 }
                 handler = null;

src/observable/list/SortedMapList.js

@@ -118,7 +118,7 @@ export default class SortedMapList extends BaseObservableList {
     }
 
     get(index) {
-        return this._sourceMap[index];
+        return this._sortedPairs[index];
     }
 
     get length() {
@@ -126,11 +126,13 @@ export default class SortedMapList extends BaseObservableList {
     }
 
     [Symbol.iterator]() {
-        return this._sortedPairs;
+        return this._sortedPairs.values();
     }
 }
 
 //#ifdef TESTS
+import ObservableMap from "../map/ObservableMap.js";
+
 export function tests() {
     return {
         test_sortIndex(assert) {
@@ -154,6 +156,17 @@ export function tests() {
             assert.deepEqual(a, [1, 2, 5, 8]);
             let idx = sortedIndex(a, 2, cmp);
             assert.equal(idx, 1);
+        },
+
+        test_initial_values(assert) {
+            const map = new ObservableMap([
+                ["a", 50],
+                ["b", 6],
+                ["c", -5],
+            ]);
+            const list = new SortedMapList(map, (a, b) => a - b);
+            list.subscribe({}); //needed to populate iterator
+            assert.deepEqual(Array.from(list), [-5, 6, 50]);
         }
     }
 }