Defining mock responses in Postman - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Purpose of Mock Responses in Postman

What is the main purpose of defining mock responses in Postman?

A To automatically generate API documentation

B To simulate API responses without calling the actual server

C To deploy APIs to production environments

D To monitor live API traffic in real-time

💡 Hint

Think about why you might want to test an API before it is ready or available.

Mock responses let you simulate how an API would respond without needing the real backend. This helps in early testing and development.

❓ Predict Output

intermediate

Output of a Mock Response Setup

Given this Postman mock response setup, what will be the HTTP status code returned when the mock is called?

Postman

{
  "name": "User Info Mock",
  "request": {
    "method": "GET",
    "url": "/user/info"
  },
  "response": {
    "status": 200,
    "body": "{\"name\": \"Alice\", \"age\": 30}",
    "headers": [{"key": "Content-Type", "value": "application/json"}]
  }
}

A 500

B 404

C 401

D 200

💡 Hint

Look at the status field inside the response object.

The mock response is configured with status 200, so calling this mock will return HTTP 200 OK.

❓ assertion

advanced

Correct Assertion for Mock Response Body

Which Postman test script assertion correctly verifies that the mock response body contains the user's name as 'Alice'?

Postman

pm.test("User name is Alice", () => {
  const jsonData = pm.response.json();
  // Which assertion goes here?
});

A pm.expect(jsonData.name).to.eql('Alice');

B pm.expect(jsonData.age).to.eql('Alice');

C pm.expect(pm.response.text()).to.include('Bob');

D pm.expect(jsonData.name).to.be.undefined;

💡 Hint

Check the property that holds the user's name and compare it to 'Alice'.

The correct assertion checks that the name property in the JSON response equals 'Alice'.

🔧 Debug

advanced

Identify the Error in Mock Response Setup

What error will occur when this Postman mock response is called?

Postman

{
  "name": "Invalid Mock",
  "request": {
    "method": "POST",
    "url": "/submit"
  },
  "response": {
    "status": "two hundred",
    "body": "Success",
    "headers": [{"key": "Content-Type", "value": "text/plain"}]
  }
}

A No error, mock returns status 200 automatically

B SyntaxError due to invalid JSON format

C Runtime error because status code must be a number, not a string

D TypeError because body must be an object, not a string

💡 Hint

Check the data type of the status field.

The status code must be a number. Using a string like 'two hundred' causes a runtime error when Postman tries to send the response.

❓ framework

expert

Best Practice for Mock Response Matching in Postman

Which option describes the best practice to ensure Postman mock server returns the correct response when multiple mocks have similar request URLs?

A Use exact HTTP method and URL path matching with query parameters included if needed

B Define mocks with only the URL path and ignore HTTP methods to simplify matching

C Use random response selection to test different scenarios automatically

D Create one mock with a wildcard URL to handle all requests

💡 Hint

Think about how Postman decides which mock response to send when requests are similar.

Postman matches mocks based on HTTP method and exact URL path including query parameters to ensure the correct response is returned.