Assertions

Assertions in Postman are based on the capabilities of the Chai Assertion Library. You can read an extensive documentation on Chai by visiting http://chaijs.com/api/bdd/

How find object in array by property value?

Given the following response:

{
    "companyId": 10101,
    "regionId": 36554,
    "filters": [
        {
            "id": 101,
            "name": "VENDOR",
            "isAllowed": false
        },
        {
            "id": 102,
            "name": "COUNTRY",
            "isAllowed": true
        },
        {
            "id": 103,
            "name": "MANUFACTURER",
            "isAllowed": false
        }
    ]
}

Assert that the property isAllowed is true for the COUNTRY filter.

pm.test("Check the country filter is allowed", function () {
    // Parse response body
    var jsonData = pm.response.json();

    // Find the array index for the COUNTRY
    var countryFilterIndex = jsonData.filters.map(
            function(filter) {
                return filter.name; // <-- HERE is the name of the property
            }
        ).indexOf('COUNTRY'); // <-- HERE is the value we are searching for

    // Get the country filter object by using the index calculated above
    var countryFilter = jsonData.filters[countryFilterIndex];

    // Check that the country filter exists
    pm.expect(countryFilter).to.exist;

    // Check that the country filter is allowed
    pm.expect(countryFilter.isAllowed).to.be.true;
});

How find nested object by object name?

Given the following response:

{
    "id": "5a866bd667ff15546b84ab78",
    "limits": {
        "59974328d59230f9a3f946fe": {
            "lists": {
                "openPerBoard": {
                    "count": 13,
                    "status": "ok", <-- CHECK ME
                    "disableAt": 950,
                    "warnAt": 900
                },
                "totalPerBoard": {
                    "count": 20,
                    "status": "ok",  <-- CHECK ME
                    "disableAt": 950,
                    "warnAt": 900
                }
            }
        }
    }
}

You want to check the value of the status in both objects (openPerBoard, totalPerBoard). The problem is that in order to reach both objects you need first to reach the lists object, which itself is a property of a randomly named object (59974328d59230f9a3f946fe).

So we could write the whole path limits.59974328d59230f9a3f946fe.lists.openPerBoard.status but this will probably work only once.

For that reason it is first needed to search inside the limits object for the lists object. In order to make the code more readable, we will create a function for that:

function findObjectContaininsLists(limits) {
    // Iterate over the properties (keys) in the object
    for (var key in limits) {
        // console.log(key, limits[key]);
        // If the property is lists, return the lists object
        if (limits[key].hasOwnProperty('lists')) {
            // console.log(limits[key].lists);
            return limits[key].lists;
        }
    }
}

The function will iterate over the limits array to see if any object contains a lists object.

Next all we need to do is to call the function and the assertions will be trivial:

pm.test("Check status", function () {
    // Parse JSON body
    var jsonData = pm.response.json();

    // Retrieve the lists object
    var lists = findObjectContaininsLists(jsonData.limits);
    pm.expect(lists.openPerBoard.status).to.eql('ok');
    pm.expect(lists.totalPerBoard.status).to.eql('ok');
});

How to compare value of a response with an already defined variable?

Lets presume you have a value from a previous response (or other source) that is saved to a variable.

// Getting values from response
var jsonData = pm.response.json();
var username = jsonData.userName;

// Saving the value for later use
pm.globals.set("username", username);

How do you compare that variable with values from another API response?

In order to access the variable in the script, you need to use a special method, basically the companion of setting a variable. Curly brackets will not work in this case:

pm.test("Your test name", function () {
    var jsonData = pm.response.json();
    pm.expect(jsonData.value).to.eql(pm.globals.get("username"));
});

How to compare value of a response against multiple valid values?

Given the following API response:

{
    "SiteId": "aaa-ccc-xxx",
    "ACL": [
        {
            "GroupId": "xxx-xxx-xx-xxx-xx",
            "TargetType": "Subscriber"
        }
    ]
}

You want to check that TargetType is Subscriber or Customer.

The assertion can look like:

pm.test("Should be subscriber or customer", function () {
    var jsonData = pm.response.json();
    pm.expect(.TargetType).to.be.oneOf(["Subscriber", "Customer"]);
});
where:
  • jsonData.ACL[0] is the first element of the ACL array
  • to.be.oneOf allows an array of possible valid values

How to parse a HTML response to extract a specific value?

Presumed you want to get the _csrf hidden field value for assertions or later use from the response below:

<form name="loginForm" action="/login" method="POST">
        <input type="hidden" name="_csrf" value="a0e2d230-9d3e-4066-97ce-f1c3cdc37915" />
        <ul>
            <li>
                <label for="username">Username:</label>
                <input required type="text" id="username" name="username" />
            </li>
            <li>
                <label for="password">Password:</label>
                <input required type="password" id="password" name="password" />
            </li>
            <li>
                <input name="submit" type="submit" value="Login" />
            </li>
        </ul>
</form>

To parse and retrive the value, we will use the cherrio JavaScript library:

// Parse HTML and get the CSRF token
responseHTML = cheerio(pm.response.text());
console.log(responseHTML.find('[name="_csrf"]').val());

Cheerio is designed for non-browser use and implements a subset of the jQuery functionality. Read more about it at https://github.com/cheeriojs/cheerio

How to fix the error “ReferenceError: jsonData is not defined”?

If you have a script like this:

pm.test("Name should be John", function () {
    var jsonData = pm.response.json();
    pm.expect(jsonData.name).to.eql('John');
});

pm.globals.set('name', jsonData.name);

You will get the error ReferenceError: jsonData is not defined while setting the global variable.

The reason is that jsonData is only defined inside the scope of the anonymous function (the part with function() {...} inside pm.test). Where you are trying to set the global variables is outside the function, so jsonData is not defined. jsonData can only live within the scope where it was defined.

So you have multiple ways to deal with this:

  1. define jsonData outside the function, for example before your pm.test function (preferred)

    var jsonData = pm.response.json(); <-- defined outside callback
    
    pm.test("Name should be John", function () {
        pm.expect(jsonData.name).to.eql('John');
    });
    
    pm.globals.set('name', jsonData.name);
    
  2. set the environment or global variable inside the anonymous function (I would personally avoid mixing test / assertions with setting variables but it would work).

    pm.test("Name should be John", function () {
        var jsonData = pm.response.json();
        pm.expect(jsonData.name).to.eql('John');
        pm.globals.set('name', jsonData.name); // <-- usage inside callback
    });
    

Hope this helps and clarifies a bit the error.

How to do a partial object match assertion?

Given the reponse:

{
    "uid": "12344",
    "pid": "8896",
    "firstName": "Jane",
    "lastName": "Doe",
    "companyName": "ACME"
}

You want to assert that a part of the reponse has a specific value. For example you are not interested in the dynamic value of uid and pid but you want to assert firstName, lastName and companyName.

You can do a partial match of the response by using the to.include expression. Optionally you can check the existence of the additional properties without checking the value.

pm.test("Should include object", function () {
    var jsonData = pm.response.json();
    var expectedObject = {
        "firstName": "Jane",
        "lastName": "Doe",
        "companyName": "ACME"
    }
    pm.expect(jsonData).to.include(expectedObject);

    // Optional check if properties actually exist
    pm.expect(jsonData).to.have.property('uid');
    pm.expect(jsonData).to.have.property('pid');
});