Fix multi-bid adId in Criteo bid adapter (prebid#3340)

* Fix multi-bid adId in Criteo bid adapter

A single bid request can generate multiple bids if it has multiple
sizes. However, by default 'adId' will be filled with the bid request's
'bidId' field, so if we create two bids from the same bid request, they
will share the same 'adId'.

Because of this, Prebid will not know which bid to use once DFP makes
either of those bids win, always taking the first one (see
'auctionManager.findBidByAdId' used in 'pbjs.renderAd').

* Increment Criteo adapter version

* Add test for Criteo multi-bid fix

modules/criteoBidAdapter.js

@@ -6,7 +6,7 @@ import find from 'core-js/library/fn/array/find';
 import JSEncrypt from 'jsencrypt/bin/jsencrypt';
 import sha256 from 'crypto-js/sha256';
 
-const ADAPTER_VERSION = 15;
+const ADAPTER_VERSION = 16;
 const BIDDER_CODE = 'criteo';
 const CDB_ENDPOINT = '//bidder.criteo.com/cdb';
 const CRITEO_VENDOR_ID = 91;
@@ -98,6 +98,7 @@ export const spec = {
         const bidId = bidRequest.bidId;
         const bid = {
           requestId: bidId,
+          adId: slot.bidId || utils.getUniqueIdentifierStr(),
           cpm: slot.cpm,
           currency: slot.currency,
           netRevenue: true,

test/spec/modules/criteoBidAdapter_spec.js

@@ -1,5 +1,7 @@
 import { expect } from 'chai';
 import { cryptoVerify, spec, FAST_BID_PUBKEY } from 'modules/criteoBidAdapter';
+import * as bidfactory from 'src/bidfactory';
+import CONSTANTS from 'src/constants.json';
 import * as utils from 'src/utils';
 
 describe('The Criteo bidding adapter', function () {
@@ -241,6 +243,7 @@ describe('The Criteo bidding adapter', function () {
         body: {
           slots: [{
             impid: 'test-requestId',
+            bidId: 'abc123',
             cpm: 1.23,
             creative: 'test-ad',
             width: 728,
@@ -261,6 +264,7 @@ describe('The Criteo bidding adapter', function () {
       const bids = spec.interpretResponse(response, request);
       expect(bids).to.have.lengthOf(1);
       expect(bids[0].requestId).to.equal('test-bidId');
+      expect(bids[0].adId).to.equal('abc123');
       expect(bids[0].cpm).to.equal(1.23);
       expect(bids[0].ad).to.equal('test-ad');
       expect(bids[0].width).to.equal(728);
@@ -297,6 +301,40 @@ describe('The Criteo bidding adapter', function () {
       expect(bids[0].width).to.equal(728);
       expect(bids[0].height).to.equal(90);
     });
+
+    it('should generate unique adIds if none are returned by the endpoint', function () {
+      const response = {
+        body: {
+          slots: [{
+            impid: 'test-requestId',
+            cpm: 1.23,
+            creative: 'test-ad',
+            width: 300,
+            height: 250,
+          }, {
+            impid: 'test-requestId',
+            cpm: 4.56,
+            creative: 'test-ad',
+            width: 728,
+            height: 90,
+          }],
+        },
+      };
+      const request = {
+        bidRequests: [{
+          adUnitCode: 'test-requestId',
+          bidId: 'test-bidId',
+          sizes: [[300, 250], [728, 90]],
+          params: {
+            networkId: 456,
+          }
+        }]
+      };
+      const bids = spec.interpretResponse(response, request);
+      expect(bids).to.have.lengthOf(2);
+      const prebidBids = bids.map(bid => Object.assign(bidfactory.createBid(CONSTANTS.STATUS.GOOD, request.bidRequests[0]), bid));
+      expect(prebidBids[0].adId).to.not.equal(prebidBids[1].adId);
+    });
   });
 
   describe('cryptoVerify', function () {