Clarify ad unit media filtering warning (#1903)

* Clarify ad unit media filtering warning

* Update message for video too

* Extract common message logic

src/prebid.js

@@ -384,27 +384,19 @@ $$PREBID_GLOBAL$$.requestBids = function ({ bidsBackHandler, timeout, adUnits, a
   adUnits.filter(videoAdUnit).filter(hasNonVideoBidder).forEach(adUnit => {
     const nonVideoBidders = adUnit.bids
       .filter(bid => !videoBidder(bid))
-      .map(bid => bid.bidder)
-      .join(', ');
+      .map(bid => bid.bidder);
 
-    utils.logError(`
-      ${adUnit.code} is a 'video' ad unit but contains non-video bidder(s) ${nonVideoBidders}.
-      No Prebid demand requests will be triggered for those bidders.
-    `);
+    utils.logWarn(utils.unsupportedBidderMessage(adUnit, nonVideoBidders));
     adUnit.bids = adUnit.bids.filter(videoBidder);
   });
 
   // for native-enabled adUnits, only request bids for bidders that support native
   adUnits.filter(nativeAdUnit).filter(hasNonNativeBidder).forEach(adUnit => {
     const nonNativeBidders = adUnit.bids
       .filter(bid => !nativeBidder(bid))
-      .map(bid => bid.bidder)
-      .join(', ');
+      .map(bid => bid.bidder);
 
-    utils.logError(`
-      ${adUnit.code} is a 'native' ad unit but contains non-native bidder(s) ${nonNativeBidders}.
-      No Prebid demand requests will be triggered for those bidders.
-    `);
+    utils.logWarn(utils.unsupportedBidderMessage(adUnit, nonNativeBidders));
     adUnit.bids = adUnit.bids.filter(nativeBidder);
   });
 

src/utils.js

@@ -794,3 +794,20 @@ export function isValidMediaTypes(mediaTypes) {
 
   return true;
 }
+
+/**
+ * Constructs warning message for when unsupported bidders are dropped from an adunit
+ * @param {Object} adUnit ad unit from which the bidder is being dropped
+ * @param {Array} unSupportedBidders arrary of bidder codes that are not compatible with the adUnit
+ * @return {string} warning message to display when condition is met
+ */
+export function unsupportedBidderMessage(adUnit, unSupportedBidders) {
+  const mediaType = adUnit.mediaType || Object.keys(adUnit.mediaTypes).join(', ');
+  const plural = unSupportedBidders.length === 1 ? 'This bidder' : 'These bidders';
+
+  return `
+    ${adUnit.code} is a ${mediaType} ad unit
+    containing bidders that don't support ${mediaType}: ${unSupportedBidders.join(', ')}.
+    ${plural} won't fetch demand.
+  `;
+}