add promotion viewed event (#46)

Author: niallzato

Example/Tests/Tests.m

@@ -306,6 +306,30 @@
         }];
     });
 
+    it(@"track Promotion Viewed", ^{
+        SEGTrackPayload *payload = [[SEGTrackPayload alloc] initWithEvent:@"Promotion Viewed"
+            properties:@{
+                @"product_id" : @"507f1f77bcf86cd799439011",
+                @"category" : @"Games",
+                @"name" : @"Monopoly 3rd Edition",
+                @"price" : @18.99,
+                @"quantity" : @1,
+                @"currency" : @"usd",
+            }
+            context:@{}
+            integrations:@{}];
+
+        [integration track:payload];
+        [verify(mockFirebase) logEventWithName:@"present_offer" parameters:@{
+            @"item_id" : @"507f1f77bcf86cd799439011",
+            @"item_category" : @"Games",
+            @"item_name" : @"Monopoly 3rd Edition",
+            @"price" : @18.99,
+            @"quantity" : @1,
+            @"currency" : @"usd",
+        }];
+    });
+
     it(@"track Payment Info Entered", ^{
         SEGTrackPayload *payload = [[SEGTrackPayload alloc] initWithEvent:@"Payment Info Entered"
             properties:@{

Segment-Firebase/Classes/SEGFirebaseIntegration.m

@@ -76,6 +76,7 @@ - (NSString *)formatFirebaseEventNames:(NSString *)event
                                              kFIREventAddToCart, @"Product Added",
                                              kFIREventRemoveFromCart, @"Product Removed",
                                              kFIREventBeginCheckout, @"Checkout Started",
+                                             kFIREventPresentOffer, @"Promotion Viewed",
                                              kFIREventAddPaymentInfo, @"Payment Info Entered",
                                              kFIREventEcommercePurchase, @"Order Completed",
                                              kFIREventPurchaseRefund, @"Order Refunded",