JSON value assertions in Postman - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a JSON value assertion in Postman?

It is a check in Postman tests that verifies if a specific value in the JSON response matches the expected value.

beginner

How do you access a JSON value in Postman test scripts?

Use `pm.response.json()` to parse the response, then access values like `jsonData.key` or `jsonData['key']`.

beginner

Example of a simple JSON value assertion in Postman?

```javascript
const jsonData = pm.response.json();
pm.test('Check user name', () => {
  pm.expect(jsonData.name).to.eql('John');
});
``` This checks if the 'name' value is 'John'.

beginner

What happens if a JSON value assertion fails in Postman?

The test will show as failed in the Postman test results, helping you identify issues in the API response.

beginner

Why use JSON value assertions in API testing?

To ensure the API returns correct and expected data, improving reliability and catching errors early.

Which Postman method parses the JSON response body?

A pm.response.body()

B pm.response.text()

C pm.response.json()

D pm.request.json()

pm.response.json() parses the response body as JSON so you can access its values.

How do you assert that a JSON key 'status' equals 'success' in Postman?

A pm.expect(jsonData.status).to.eql('success')

B pm.expect(jsonData.status).to.be.true()

C pm.expect(jsonData.status).to.exist()

D pm.expect(jsonData.status).to.be.null()

Use to.eql('success') to check exact value equality.

What does a failed JSON value assertion indicate?

A The API response value did not match the expected value

B The API is down

C The test script has syntax errors

D The JSON response is empty

A failed assertion means the actual value differs from what was expected.

Which of these is a best practice for JSON value assertions?

A Check every key in the JSON response

B Check only the keys you need to verify

C Ignore JSON structure and check text only

D Use random values for assertions

Checking only necessary keys keeps tests focused and efficient.

In Postman, where do you write JSON value assertions?

A In the Body tab

B In the Pre-request Script tab

C In the Headers tab

D In the Tests tab of the request

The Tests tab is where you write scripts to check response values.

Explain how to write a JSON value assertion in Postman to check if a response key 'age' equals 30.

Think about parsing JSON and using pm.expect to compare values.

Describe what happens when a JSON value assertion fails during a Postman test run.

Consider how Postman shows test results.