Writing tests and assertions in scripts

You can add test specifications and assertions to your scripts using the pm.test and pm.expect methods.

pm.test

Use the pm.test method to add test specifications inside Pre-request or Post-response scripts (for HTTP) or Before invoke, On message, or After response scripts (for gRPC). Tests include a name and assertion function.

A test for HTTP request would look something like the following:

pm.test(testName , specFunction)

Where:

• testName - A string that contains the test’s name.
• specFunction - The function defining the test logic.

Postman outputs test results as part of the response. The pm.test method returns the pm object, enabling you to chain calls.

Examples

Check whether a response is valid to proceed:

pm.test("response should be okay to process", function () {
  pm.response.to.not.be.error;
  pm.response.to.have.jsonBody('data') // checks existence of a property in the JSON response
  pm.response.to.have.jsonBody('data', { "id" : 1 }); // Performs deep comparison
});

Test an asynchronous function using an optional done callback:

pm.test('async test', function (done) {
  setTimeout(() => {
    pm.expect(pm.response.code).to.equal(200);
    done();
  }, 1500);
});

Get the total number of tests run from a specific location in code:

pm.test.index(); // Number

Include multiple assertions to group the related assertions in a single gRPC test:

pm.test("Should receive update events for both users", function () {
  pm.response.messages.to.include({ action: 'update', userId: 'user1' });
  pm.response.messages.to.include({ action: 'update', userId: 'user2' });
});

Get the total number of tests run from a specific location in code:

pm.test.index; () =>number

Skip a test:

pm.test.skip: (testName, specFunction) => pm

pm.expect

The pm.expect method enables you to write assertions on your response data using ChaiJS expect BDD syntax.

pm.expect(value: *): Assertion

• value - What you want to test, where * can be any type of value, such as a string or integer.
• Assertion - A Chai Assertion object containing chainable methods.

You can also use pm.response.to.have.* and pm.response.to.be.* to build your assertions.

See Postman test script examples for more assertions.

Examples

Check if the response returns an HTTP 200 OK response:

pm.test("Response status code is 200", function () {
    // value: pm.response.code (a number)
    // Assertion: checks if it equals 200
    pm.expect(pm.response.code).to.eql(200);
});

Check if the request’s response body contains the true value:

pm.test("Response body has success = true", function () {
    const jsonData = pm.response.json();
    // value: jsonData.success (a boolean)
    // Assertion: checks if it equals true
    pm.expect(jsonData.success).to.eql(true);
});