Unable to find the duplicate elements from API response - selenium

Question

We were testing an API and recently got an issue, some of the customers cannot log in to the website.
We found the issue and it is because of Duplicate keys in the API response, it is giving response even if the API contains the duplicate key.
So tests are not helping for the duplicate key conditions,So can anyone please help me or guide how I can find whether there is a duplicate element in the API response.
Tool: postman
Below is the sample API output,
In the below JSON output from API we can find there are duplicates for "operatingSystem",like this duplicate key is coming for different elements.
Since there is no way to debug the API for a while due to some reasons,so need to find out these duplicate cases.
Any idea or suggestions will be much appreciated.Thanks in advance.
JSON
eg: {
"code": 2,
"deviceId": "ID",
"deviceName": "Test",
"platform": "x64",
"operatingSystem": "test",
"operatingSystem": "test",
"gde": 000,
"productVersion": "0.0",
"build": "00000",
"receipt": null
}
How could we handle such a situation. Do we have any method to automate/test this case?

Answer 1

Here's something you can try although it's a bit convoluted. pm.response.json() will normalize the response and remove any duplicates i.e. you won't be able to detect any. So what you can do is take the response in text then manipulate it into a list and look for duplicates there. I used a map object so that if the map already contains a given key then set a flag and fail the test.
This is not thoroughly tested but it should give you an idea or at least a starting point to tackle the problem:
var jsonBody = pm.response.text();
var str = jsonBody.substring(1, jsonBody.length-1);
var keyArr = str.split(",");
var keyMap = {};
var foundDups = false;
for (var i = 0; i < keyArr.length; i++) {
var key = keyArr[i].split(":")[0];
if(!(key in keyMap)) {
keyMap[key] = key;
console.log("added key " + key);
}
else {
console.log("found duplicate: " + key);
foundDups = true;
break;
}
}
pm.test("Look for dups", function() {
pm.expect(foundDups).to.eql(false);
});