Currency module: Don't block 'responsesReady' when rates are present and no conversion is done

[samuel-palmer-relevant-digital]

Type of change

• Bugfix

Description of change

This fix makes sure to not block the call to adapterDone() call in src/auction.js when the currency-module is being used with pbjs.setConfig({ currency: { rates: { ... }, ... } }) when there are no currency-conversions necessary in the auction.

The issue as that adapterDone() is never called by the following code in src/auction.js under these conditions - as the finally-callback is never executed:

responsesReady(GreedyPromise.resolve()).finally(() => adapterDone.call(this));

The reason is that responseReady.resolve() is never called in modules/currency.js as processBidResponseQueue() is not called when it's not necessary to fetch the currency-file and there is no bid-response with a currency that differs from the adServerCurrency.

Example

The code below delays the bidBackHandler for ~3 seconds (the timeout) because of the bug. With the fix the extra delay disappears.

<script src="https://cdn.jsdelivr.net/npm/prebid.js@latest/dist/not-for-prod/prebid.js"></script>
<h3 id="message">Loading...<h3>
<iframe id="example" scrolling="no" frameborder="0"></iframe>
<script>
    pbjs.addAdUnits([
        {
            code: 'example',
            mediaTypes: { banner: { sizes: [[300, 250]] } },
            bids: [{
                bidder: 'pubmatic',
                params: { publisherId: '45710', adSlot: '829342' },
            }]
        },
    ]);
    pbjs.setConfig({
        currency: {
            adServerCurrency: 'USD', // Change to 'SEK' will remove delay
            rates: { SEK: { USD: 0.1 } }
        },
    });
    const start = new Date();
    pbjs.requestBids({
        bidsBackHandler: () => {
            const [bid] = pbjs.getHighestCpmBids('example');
            if (bid) {
                const doc = example.contentDocument;
                message.innerHTML = `Ms until render: ${new Date() - start}<br>Ms to respond: ${bid.timeToRespond}`;
                pbjs.renderAd(doc, bid.adId);
                doc.body.style.margin = 0;
            }
        },
    });
</script>