Added orderWatchCount to return total count of orders watched.

packages/order-watcher/src/order_watcher/order_watcher.ts

@@ -213,6 +213,9 @@ export class OrderWatcher {
         this._expirationWatcher.unsubscribe();
         intervalUtils.clearAsyncExcludingInterval(this._cleanupJobIntervalIdIfExists);
     }
+    public getWatchCount(): number {
+        return _.size(this._orderByOrderHash);
+    }
     private async _cleanupAsync(): Promise<void> {
         for (const orderHash of _.keys(this._orderByOrderHash)) {
             this._cleanupOrderRelatedState(orderHash);

packages/order-watcher/test/order_watcher_test.ts

@@ -140,6 +140,23 @@ describe('OrderWatcher', () => {
             expect(() => orderWatcher.subscribe(_.noop.bind(_))).to.throw(OrderWatcherError.SubscriptionAlreadyPresent);
         });
     });
+    describe('#getWatchCount', async () => {
+        it('should increment and decrement order counts', async() => {
+            signedOrder = await fillScenarios.createFillableSignedOrderAsync(
+                makerAssetData,
+                takerAssetData,
+                makerAddress,
+                takerAddress,
+                fillableAmount,
+            );
+            const orderHash = orderHashUtils.getOrderHashHex(signedOrder);
+            expect(orderWatcher.getWatchCount()).to.be.eq(0);
+            await orderWatcher.addOrderAsync(signedOrder);
+            expect(orderWatcher.getWatchCount()).to.be.eq(1);
+            orderWatcher.removeOrder(orderHash);
+            expect(orderWatcher.getWatchCount()).to.be.eq(0);
+        });
+    });
     describe('tests with cleanup', async () => {
         afterEach(async () => {
             orderWatcher.unsubscribe();