Price bucket with 0,3$ step - incorrect granularity

[haroldpussat]

Type of issue

Question

Description

Hi,
We are using prebid 0.34 with a custom price bucket configuration. This price bucket is divided as below

`var customConfigObject = {
"buckets" : [{
"precision": 2,
"min" : 0.1,
"max" : 7,
"increment" : 0.02
},
{
"precision": 2,
"min" : 7,
"max" : 10,
"increment" : 0.1
},
{
"precision": 2,
"min" : 10,
"max" : 22,
"increment" : 0.3
}]
};

var pbjs = pbjs || {};
pbjs.que = pbjs.que || [];

pbjs.que.push(function() {
    pbjs.enableSendAllBids();
    pbjs.setPriceGranularity(customConfigObject);
    pbjs.setBidderSequence('random');
});

`

For bids below 10$ CPM, there is no issue and the price bucket is validated. But for bid > 10$ CPM and < 22$ CPM, we are facing price issue. The bid sent to DFP doesn't correspond to the granularity.

Example :

The pbjs debug info indicates that the granularity is well setup :
Arguments(1)0: buckets: Array(3)0: {precision: 2, min: 0.1, max: 7, increment: 0.02}1: {precision: 2, min: 7, max: 10, increment: 0.1}2: {precision: 2, min: 10.3, max: 22, increment: 0.3}length: 3__proto__: Array(0)__proto__: Objectcallee: (...)length: 1Symbol(Symbol.iterator): ƒ values()get callee: ƒ ()set callee: ƒ ()__proto__: Object
From a test page, I receive from appnexus a bid valued at 12,92$, see the network answer from appnexus

"creative_id": 90355238, "media_type_id": 1, "media_subtype_id": 1, "cpm": 12.92181, "cpm_publisher_currency": 12.92181, "is_bin_price_applied": false, "publisher_currency_code": "$",

My test page send a hb_pb at 12,90$, instead of 13$ or 12,70$. With that difference, my lineItem is not raised because hb_pb doesn't exist at 12,90$.
It seems the issue is linked with the 0,3$ granularity.
There is no error with pbjs_debug=true, only a warning

prebid.js:3 WARNING: pbjs.setPriceGranularity will be removed in Prebid 1.0. Use pbjs.setConfig({ priceGranularity: }) instead.

I also try to change the min of hte last bucket (change from 10 to 10,3, but still have the issue)

Steps to reproduce

As explained, with a custom bucket configuration and a granularity of 0,3$, the issue is raised.

Test page

If needed I can send you a test page

Expected results

The bucket configuration should be respected from 10$ to 22$ (10$ - 10,3$ - 10,6$ - 10,9$...)

Actual results

Platform details

prebid 0.34 with appnexus, criteo, Smart adapter.
I reproduce the issue with Chrome (last stable version - 64)

Other information

[haroldpussat]

FYI, issue reproduced with prebid 0.34.4

[mkendall07]

I think the problem is that the step assumption is from 0 instead of the min bucket. Thanks for the report.