Send request block in Postman - Build an Automation Script

Send a POST request with JSON body and verify response status

Preconditions (3)

Step 1: Open Postman and create a new POST request

Step 2: Enter the URL https://api.example.com/login in the request URL field

Step 3: Select POST method

Step 4: Go to the Body tab and select raw and JSON format

Step 5: Enter the JSON body: {"username": "testuser", "password": "Test@123"}

Step 6: Click the Send button

Step 7: Observe the response status code and body

✅ Expected Result: Response status code is 200 and response body contains a token field

Automation Requirements - Postman/Newman

Assertions Needed:

Verify response status code is 200

Verify response body contains a non-empty token field

Best Practices:

Use environment variables for URL and credentials

Use test scripts in Postman to assert response

Avoid hardcoding sensitive data in the request body

Use descriptive names for requests and collections

Automated Solution

Postman

pm.test('Status code is 200', function () {
    pm.response.to.have.status(200);
});
pm.test('Response has token', function () {
    var jsonData = pm.response.json();
    pm.expect(jsonData.token).to.exist;
    pm.expect(jsonData.token).to.be.a('string').that.is.not.empty;
});

The first test checks if the response status code is exactly 200, which means the request was successful.

The second test parses the JSON response body and verifies that the token field exists, is a string, and is not empty. This confirms that the login was successful and a token was returned.

Using pm.test allows grouping assertions with clear descriptions. Parsing JSON with pm.response.json() is the standard way to access response data in Postman scripts.

Common Mistakes - 3 Pitfalls

Hardcoding the API URL and credentials directly in the request body

Not checking the response status code before accessing response body

Using incorrect assertion syntax like pm.expect(response.status).toBe(200)

Bonus Challenge

Now add data-driven testing with 3 different sets of user credentials to verify login success or failure.

Show Hint

Practice

1. What is the main purpose of the Send request block in Postman?

easy

A. To call APIs and test their responses automatically

B. To design the user interface of an application

C. To write database queries

D. To create user accounts in Postman

Solution

1. Step 1: Understand the role of Send request block

   The Send request block is used to make API calls and check how the API behaves.

2. Step 2: Compare options with the purpose

   Only To call APIs and test their responses automatically correctly describes calling APIs and testing responses automatically.

3. Final Answer:

   To call APIs and test their responses automatically -> Option A

4. Quick Check:

   Send request block = call and test APIs [OK]

Hint: Send request block is for API calls and testing [OK]

Common Mistakes:

• Confusing Send request with UI design
• Thinking it writes database queries
• Assuming it manages user accounts

2. Which of the following is the correct way to send a GET request using the Send request block in Postman scripts?

easy

A. pm.sendRequest({url: 'https://api.example.com', method: 'GET'}, callback);

B. pm.sendRequest('https://api.example.com', 'GET', callback);

C. sendRequest({url: 'https://api.example.com', method: 'GET'});

D. pm.requestSend({url: 'https://api.example.com', method: 'GET'}, callback);

Solution

1. Step 1: Recall correct syntax for pm.sendRequest

   The correct syntax uses an object with url and method, plus a callback function.

2. Step 2: Check each option's syntax

   pm.sendRequest({url: 'https://api.example.com', method: 'GET'}, callback); matches the correct syntax: pm.sendRequest({url: ..., method: ...}, callback); others have wrong function names or argument formats.

3. Final Answer:

   pm.sendRequest({url: 'https://api.example.com', method: 'GET'}, callback); -> Option A

4. Quick Check:

   pm.sendRequest uses object + callback [OK]

Hint: Use object with url and method in pm.sendRequest [OK]

Common Mistakes:

• Passing URL and method as separate arguments
• Using wrong function names like sendRequest or pm.requestSend
• Omitting the callback function

3. Consider this Postman test script snippet:

pm.sendRequest({
  url: 'https://api.example.com/data',
  method: 'GET'
}, function (err, res) {
  pm.test('Status code is 200', function () {
    pm.expect(res.code).to.eql(200);
  });
});

What will happen when this script runs?

medium

A. The script will throw a syntax error

B. The test will fail because the callback is missing

C. The test will always pass regardless of status code

D. The test will pass if the API returns status 200

Solution

1. Step 1: Analyze the sendRequest call and callback

   The script sends a GET request and uses a callback to check the response status code.

2. Step 2: Understand the test assertion

   The test asserts that the response code equals 200, so it passes only if the API returns 200.

3. Final Answer:

   The test will pass if the API returns status 200 -> Option D

4. Quick Check:

   Test passes if res.code == 200 [OK]

Hint: Test passes only if response code matches 200 [OK]

Common Mistakes:

• Thinking callback is missing
• Assuming syntax error without checking code
• Believing test passes regardless of response

4. You wrote this Postman script to send a request:

pm.sendRequest({
  url: 'https://api.example.com/users',
  method: 'POST',
  body: {
    mode: 'raw',
    raw: JSON.stringify({name: 'John'})
  }
}, function (err, res) {
  // callback function
});

But the request is not sent. What is the likely problem?

medium

A. Incorrect HTTP method; POST is not allowed

B. Missing callback function to handle the response

C. Body should be sent as form-data, not raw JSON

D. URL is invalid and causes failure

Solution

1. Step 1: Check the sendRequest syntax

   pm.sendRequest requires a callback function as the second argument to execute the request properly.

2. Step 2: Identify missing callback

   The script lacks the callback function, so the request is not sent or handled.

3. Final Answer:

   Missing callback function to handle the response -> Option B

4. Quick Check:

   sendRequest needs callback to send request [OK]

Hint: Always include callback function in pm.sendRequest [OK]

Common Mistakes:

• Ignoring the need for callback function
• Assuming HTTP method is wrong without checking API docs
• Thinking body format is always wrong
• Blaming URL without testing it

5. You want to send a POST request with JSON data and verify the response contains a field success set to true. Which Postman script correctly sends the request and tests the response?

hard

A. pm.sendRequest({url: 'https://api.example.com/save', method: 'POST', body: {data: 123}}, function (err, res) { pm.test('Success is true', () => { pm.expect(res.success).to.be.true; }); });

B. pm.sendRequest('https://api.example.com/save', 'POST', {data: 123}, function (err, res) { pm.expect(res.success).to.equal(true); });

C. pm.sendRequest({url: 'https://api.example.com/save', method: 'POST', header: {'Content-Type': 'application/json'}, body: {mode: 'raw', raw: JSON.stringify({data: 123})}}, function (err, res) { pm.test('Success is true', () => { pm.expect(res.json().success).to.be.true; }); });

D. pm.sendRequest({url: 'https://api.example.com/save', method: 'POST', body: {mode: 'formdata', formdata: {data: 123}}}, function (err, res) { pm.test('Success is true', () => { pm.expect(res.json().success).to.be.true; }); });

Solution

1. Step 1: Check request format for JSON POST

   The correct script sets Content-Type header to application/json and sends body as raw JSON string.

2. Step 2: Verify response test syntax

   The correct script uses res.json() to parse response and checks success field is true with valid assertion.

3. Step 3: Compare other options

   The incorrect options use wrong argument formats, miss headers, or send formdata instead of raw JSON.

4. Final Answer:

   pm.sendRequest({url: 'https://api.example.com/save', method: 'POST', header: {'Content-Type': 'application/json'}, body: {mode: 'raw', raw: JSON.stringify({data: 123})}}, function (err, res) { pm.test('Success is true', () => { pm.expect(res.json().success).to.be.true; }); }); -> Option C

5. Quick Check:

   JSON POST: header + raw body + res.json().success [OK]

Hint: Set JSON header and use res.json() to test response [OK]

Common Mistakes:

• Omitting Content-Type header for JSON
• Sending body as plain object without raw string
• Using wrong argument order in sendRequest
• Testing response without parsing JSON