feat(analytics): allow custom event parameters for begin_checkout and purchase events (#7760)

* Allow extra params in begin_checkout/purchase

* Add tests

Author: Minishlink

packages/analytics/__tests__/analytics.test.ts

@@ -272,6 +272,16 @@ describe('Analytics', function () {
         }),
       ).toThrowError('firebase.analytics().logBeginCheckout(*):');
     });
+
+    it('accepts arbitrary custom event parameters', function () {
+      expect(() =>
+        firebase.analytics().logBeginCheckout({
+          value: 123,
+          currency: 'EUR',
+          foo: 'bar',
+        }),
+      ).not.toThrow();
+    });
   });
 
   describe('logGenerateLead()', function () {
@@ -459,6 +469,16 @@ describe('Analytics', function () {
         }),
       ).toThrowError('firebase.analytics().logPurchase(*):');
     });
+
+    it('accepts arbitrary custom event parameters', function () {
+      expect(() =>
+        firebase.analytics().logPurchase({
+          value: 123,
+          currency: 'EUR',
+          foo: 'bar',
+        }),
+      ).not.toThrow();
+    });
   });
 
   describe('logRefund()', function () {

packages/analytics/lib/index.d.ts

@@ -179,6 +179,10 @@ export namespace FirebaseAnalyticsTypes {
     coupon?: string;
 
     items?: Item[];
+    /**
+     * Custom event parameters.
+     */
+    [key: string]: any;
   }
 
   export interface CampaignDetailsEventParameters {
@@ -334,6 +338,10 @@ export namespace FirebaseAnalyticsTypes {
      * A single ID for a ecommerce group transaction.
      */
     transaction_id?: string;
+    /**
+     * Custom event parameters.
+     */
+    [key: string]: any;
   }
 
   export interface ScreenViewParameters {

packages/analytics/lib/structs.js

@@ -65,7 +65,7 @@ export const AddToWishlist = struct({
   currency: 'string?',
 });
 
-export const BeginCheckout = struct({
+export const BeginCheckout = struct.interface({
   items: struct.optional([Item]),
   value: 'number?',
   currency: 'string?',
@@ -131,7 +131,7 @@ export const Refund = struct({
   transaction_id: 'string?',
 });
 
-export const Purchase = struct({
+export const Purchase = struct.interface({
   affiliation: 'string?',
   coupon: 'string?',
   currency: 'string?',