Postman test script examples

This page provides post-response script examples for various API testing scenarios in Postman. You can use these post-response scripts in your request to parse response data and make assertions. You can also use these scripts to validate response structure and troubleshoot common test errors.

To write your first post-response script, open a request in Postman, then select the Scripts > Post-response tab. Enter the following JavaScript code:

pm.test("Status code is 200", function () {
  pm.response.to.have.status(200);
});

This code uses the pm library to run the test method. The text string will appear in the test output. The function inside the test represents an assertion. Postman tests can use Chai Assertion Library BDD syntax, which provides options to optimize how readable your tests are to you and your collaborators. In this case, the code uses a to.have chain to express the assertion.

This test checks the response code returned by the API. If the response code is 200, the test will pass, otherwise it will fail. Select Send and go to the Test Results tab in the response area.

To learn what test results look like when they pass or fail, change the status code in the assertion code and send the request again.

You can structure your test assertions in a variety of ways, depending on how you want the results to output. The following code is an alternative way of achieving the same test as the one before using the expect syntax:

pm.test("Status code is 200", () => {
  pm.expect(pm.response.code).to.eql(200);
});

Refer to the Chai Assertion Library Docs for a complete overview of assertion syntax options.

Use multiple assertions

Your tests can include multiple assertions as part of a single test. Use this to group together related assertions:

pm.test("The response has all properties", () => {
    //parse the response JSON and test three properties
    const responseJson = pm.response.json();
    pm.expect(responseJson.type).to.eql('vip');
    pm.expect(responseJson.name).to.be.a('string');
    pm.expect(responseJson.id).to.have.lengthOf(1);
});

If any of the contained assertions fails, the test as a whole will fail. All assertions must be successful for the test to pass.

Parse response body data

To carry out assertions on your responses, you will first need to parse the data into a JavaScript object that your assertions can use.

To parse JSON data, use the following syntax:

const responseJson = pm.response.json();

To parse XML, use the following:

const responseJson = xml2Json(pm.response.text());

If you're dealing with complex XML responses you may find Console logging useful.

To parse CSV, use the CSV parse (csv-parse/lib/sync) utility:

const parse = require('csv-parse/lib/sync');
const responseJson = parse(pm.response.text());

To parse HTML, use cheerio:

const $ = cheerio.load(pm.response.text());
//output the html for testing
console.log($.html());

Handle responses that don't parse

If you can't parse the response body into JavaScript because it's not formatted as JSON, XML, HTML, CSV, or any other parsable data format, you can still make assertions on the data.

Test if the response body has a string:

pm.test("Body contains string",() => {
  pm.expect(pm.response.text()).to.include("customer_id");
});

This doesn't tell you where the string was encountered because it carries out the test on the whole response body. Test if a response matches a string:

pm.test("Body is string", function () {
  pm.response.to.have.body("whole-body-text");
});

Make assertions on the HTTP response

Your tests can check various aspects of a request response, including the body, status codes, headers, cookies, response times, and more.

Test response body

Check for particular values in the response body:

/* Response has the following structure:
{
  "name": "Jane",
  "age": 23
},
*/
pm.test("Person is Jane", () => {
  const responseJson = pm.response.json();
  pm.expect(responseJson.name).to.eql("Jane");
  pm.expect(responseJson.age).to.eql(23);
});

Test status codes

Test for the response status code:

pm.test("Status code is 201", () => {
  pm.response.to.have.status(201);
});

If you want to test for the status code being one of a set, include them all in an array and use oneOf:

pm.test("Successful POST request", () => {
  pm.expect(pm.response.code).to.be.oneOf([201,202]);
});

Check the status code text:

pm.test("Status code name has string", () => {
  pm.response.to.have.status("Created");
});

Test headers

Check that a response header is present:

pm.test("Content-Type header is present", () => {
  pm.response.to.have.header("Content-Type");
});

Test for a response header having a particular value:

pm.test("Content-Type header is application/json", () => {
  pm.expect(pm.response.headers.get('Content-Type')).to.include('application/json');
});

Test cookies

Test if a cookie is present in the response:

pm.test("Cookie isLoggedIn is present", () => {
  pm.expect(pm.cookies.has('isLoggedIn')).to.be.true;
});

Test for a particular cookie value:

pm.test("Cookie isLoggedIn has value 1", () => {
  pm.expect(pm.cookies.get('isLoggedIn')).to.eql('1');
});

Test response times

Test for the response time to be within a specified range:

pm.test("Response time is less than 200ms", () => {
  pm.expect(pm.response.responseTime).to.be.below(200);
});

Common assertion examples

The following examples of common assertions might help you write your post-response scripts.

For a more comprehensive overview of what you can include in your assertions, refer to the Chai Assertion Library Docs.

Assert a response value against a variable

Check if a response property has the same value as a variable (this example uses an environment variable):

pm.test("Response property matches environment variable", function () {
  pm.expect(pm.response.json().name).to.eql(pm.environment.get("name"));
});

See Using variables to learn more about using variables in your post-response scripts.

Assert a value type

Test the type of any part of the response:

/* Response has the following structure:
{
  "name": "Jane",
  "age": 29,
  "hobbies": [
    "skating",
    "painting"
  ],
  "email": null
},
*/
const jsonData = pm.response.json();
pm.test("Test data type of the response", () => {
  pm.expect(jsonData).to.be.an("object");
  pm.expect(jsonData.name).to.be.a("string");
  pm.expect(jsonData.age).to.be.a("number");
  pm.expect(jsonData.hobbies).to.be.an("array");
  pm.expect(jsonData.website).to.be.undefined;
  pm.expect(jsonData.email).to.be.null;
});

Assert array properties

Check if an array is empty, and if it has particular items:

/* Response has the following structure:
{
  "errors": [],
  "areas": [ "goods", "services" ],
  "settings": [
    {
      "type": "notification",
      "detail": [ "email", "sms" ]
    },
    {
      "type": "visual",
      "detail": [ "light", "large" ]
    }
  ]
},
*/

const jsonData = pm.response.json();
pm.test("Test array properties", () => {
    //errors array is empty
  pm.expect(jsonData.errors).to.be.empty;
    //areas array includes "goods"
  pm.expect(jsonData.areas).to.include("goods");
    //get the notification settings object
  const notificationSettings = jsonData.settings.find
      (m => m.type === "notification");
  pm.expect(notificationSettings)
    .to.be.an("object", "Could not find the setting");
    //detail array must include "sms"
  pm.expect(notificationSettings.detail).to.include("sms");
    //detail array must include all listed
  pm.expect(notificationSettings.detail)
    .to.have.members(["email", "sms"]);
});

The order in .members doesn't affect the test.

Assert object properties

Assert that an object has keys or properties:

/* Response has the following structure:
{
  "a": 1,
  "b": 2
},
*/
pm.expect({a: 1, b: 2}).to.have.all.keys('a', 'b');
pm.expect({a: 1, b: 2}).to.have.any.keys('a', 'b');
pm.expect({a: 1, b: 2}).to.not.have.any.keys('c', 'd');
pm.expect({a: 1}).to.have.property('a');
pm.expect({a: 1, b: 2}).to.be.a('object')
  .that.has.all.keys('a', 'b');

Target can be an object, set, array or map. If .keys is run without .all or .any, the expression defaults to .all. As .keys behavior varies based on the target type, it's recommended to check the type before using .keys with .a.

Assert that a value is in a set

Check a response value against a list of valid options:

/* Response has the following structure:
{
  "type": "Subscriber"
},
*/

pm.test("Value is in valid list", () => {
  pm.expect(pm.response.json().type)
    .to.be.oneOf(["Subscriber", "Customer", "User"]);
});

Assert that an object is contained

Check that an object is part of a parent object:

/* Response has the following structure:
{
  "id": "d8893057-3e91-4cdd-a36f-a0af460b6373",
  "created": true,
  "errors": []
},
*/

pm.test("Object is contained", () => {
  const expectedObject = {
    "created": true,
    "errors": []
  };
  pm.expect(pm.response.json()).to.deep.include(expectedObject);
});

The .deep assertion causes all .equal, .include, .members, .keys, and .property assertions that follow in the chain to use deep equality instead of strict (===) equality.

Assert the current environment

Check the active environment in Postman:

pm.test("Check the active environment", () => {
  pm.expect(pm.environment.name).to.eql("Production");
});

Troubleshoot common test errors

When you encounter errors or unexpected behavior in your post-response scripts, the Postman Console can help you to identify the source. By combining console.log(), console.info(), console.warn(), and console.error() debug statements with your test assertions, you can examine the content of the HTTP requests and responses, and Postman data items such as variables. You can also use the console.clear() method to clear information from the console. Select Console from the Postman footer to open it.

Log the value of a variable or response property:

console.log(pm.collectionVariables.get("name"));
console.log(pm.response.json().name);

Log the type of variable or response property:

console.log(typeof pm.response.json().id);

Use Console logs to mark code, sometimes known as "trace statements":

if (pm.response.json().id) {
  console.log("id was found!");
  // do something
} else {
  console.log("no id ...");
  //do something else
}

Assertion deep equality error

You might encounter the AssertionError: expected <value> to deeply equal '<value>' error. For example, this would arise with the following code:

pm.expect(1).to.eql("1");

This happens because the test is comparing a number to a string value. The test will only return true if both the type and value are equal.

Variable not defined error

You might encounter the ReferenceError: <variable> is not defined error. This typically happens when you're attempting to reference a variable that hasn't been declared or is outside the scope of your test code.

In the following example, a JSON object is the value of a variable in the first test. The second test is attempting to reference the variable, but it can't because the variable is outside the scope of the second test's code.

/* Response has the following structure:
{
  "name": "John",
  "age": 29
},
*/
pm.test("Test 1", () => {
  const jsonData = pm.response.json();
  pm.expect(jsonData.name).to.eql("John");
});

pm.test("Test 2", () => {
  pm.expect(jsonData.age).to.eql(29); // ReferenceError: jsonData is not defined
});

Make sure variables are available at the global scope if test functions needs to reference it. In the previous example, moving const jsonData = pm.response.json(); before the first pm.test would make it available to both test functions.

Assertion undefined error

You might encounter the AssertionError: expected undefined to deeply equal <value> error. Typically this happens when you are referring to a property that doesn't exist or is out of scope.

const jsonData = pm.response.json();
pm.expect(jsonData.name).to.eql("John");

In this example, if you get the error AssertionError: expected undefined to deeply equal 'John', this indicates that the name property isn't defined in the jsonData object.

Test not failing

There may be occasions where you expect a test to fail, and it doesn't. Make sure your test code is syntactically correct, then resend your request.

In the following example, the test is expected to fail because true doesn't equal false. The test actually passes because the pm.test function isn't correctly defined. The pm.test function is missing the first parameter, which is a text string that displays in the test result output. You can learn more about defining tests using the pm.test function.

pm.test( function () {
    pm.expect(true).to.eql(false);
});

Validate response structure

You can validate your JSON Schema with Ajv. In the following example, the test will pass only when the request includes a query parameter named alpha.

const schema = {
    required: ["args"],
    properties: {
        args: {
            required: ["alpha"],
            properties: {
                alpha: { type: "string" }
            }
        }
    }
};

pm.test('Response is valid', function() {
  pm.response.to.have.jsonSchema(schema);
});

Learn more about using Ajv JSON Schema validator, which supersedes the deprecated tv4.

Send an asynchronous request

You can send a request from your test code and log the response:

pm.sendRequest("https://postman-echo.com/get", function (err, response) {
    console.log(response.json());
});

Previous style of writing Postman tests (deprecated)

This section refers to deprecated script syntax used in earlier versions of Postman. If you are writing new scripts, use the current syntax.

The previous style of writing Postman tests relies on setting values for the tests object. Set a descriptive key for an element in the object and then assert if it's true or false. For example, the following will check if the response body has the user_id string:

tests["Body contains user_id"] = responsebody.has("user_id");

If you use the previous style of writing Postman tests, the syntax will appear in the code editor with a strikethrough to indicate that the style is deprecated. A warning will log to the Postman Console, letting you know that the style you're using is deprecated. The warning will also log syntax for the current style that's recommended instead.

Add as many keys as needed, depending on how many things you want to test for. View your test results in the response viewer under the Post-response tab. The tab header shows how many tests passed, and the keys that you set in the tests variable are listed there. If the value evaluates to true, the test passed.

//Set an environment variable
postman.setEnvironmentVariable("key", "value");

//Set a nested object as an environment variable
const array = [1, 2, 3, 4];
postman.setEnvironmentVariable("array", JSON.stringify(array, null, 2));
const obj = { a: [1, 2, 3, 4], b: { c: 'val' } };
postman.setEnvironmentVariable("obj", JSON.stringify(obj));

//Get an environment variable
postman.getEnvironmentVariable("key");

//Get an environment variable whose value is a stringified object
//(Wrap in a try-catch block if the data is coming from an unknown source)
const array = JSON.parse(postman.getEnvironmentVariable("array"));
const obj = JSON.parse(postman.getEnvironmentVariable("obj"));

//Clear an environment variable
postman.clearEnvironmentVariable("key");

//Set a global variable
postman.setGlobalVariable("key", "value");

//Get a global variable
postman.getGlobalVariable("key");

//Clear a global variable
postman.clearGlobalVariable("key");

//Set which request to run next when using the Collection Runner or Newman
postman.setNextRequest("request_name");

//Check if response body contains a string
tests["Body matches string"] = responseBody.has("string_you_want_to_search");

//Check if response body is equal to a string
tests["Body is correct"] = responseBody === "response_body_string";

//Check for a JSON value
const data = JSON.parse(responseBody);
tests["Your test name"] = data.value === 100;

//Content-Type is present (Case-insensitive checking)
tests["Content-Type is present"] = postman.getResponseHeader("Content-Type");
tests["Content-Type is present"] = postman.getResponseHeader("Content-Type");
//getResponseHeader() method returns the header value, if it exists

//Content-Type is present (Case-sensitive)
tests["Content-Type is present"] = responseHeaders.hasOwnProperty("Content-Type");

//Response time is less than 200ms
tests["Response time is less than 200ms"] = responseTime < 200;

//Response time is within a specific range
//(lower bound inclusive, upper bound exclusive)
tests["Response time is acceptable"] = _.inRange(responseTime, 100, 1001);

//Status code is 200
tests["Status code is 200"] = responseCode.code === 200;

//Code name contains a string
tests["Status code name has string"] = responseCode.name.has("Created");

//Successful POST request status code
tests["Successful POST request"] = responseCode.code === 201 || responseCode.code === 202;

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