First API request in Postman - Build an Automation Script

Send a GET request to retrieve user data

Preconditions (2)

Step 1: Open Postman application

Step 2: Create a new GET request

Step 3: Enter the URL https://jsonplaceholder.typicode.com/users/1 in the request URL field

Step 4: Click the Send button

Step 5: Observe the response status code and body

✅ Expected Result: Response status code is 200 OK and the response body contains user data with id 1

Automation Requirements - Postman (using Postman test scripts)

Assertions Needed:

Verify response status code is 200

Verify response body contains user id equal to 1

Best Practices:

Use built-in Postman test scripting with pm.* API

Write clear and simple assertions

Avoid hardcoding values except the endpoint URL

Use descriptive test names

Automated Solution

Postman

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

pm.test('Response has user id 1', function () {
    const jsonData = pm.response.json();
    pm.expect(jsonData.id).to.eql(1);
});

The first test checks that the HTTP status code returned by the API is 200, which means the request was successful.

The second test parses the JSON response body and verifies that the user id field equals 1, confirming the correct user data was returned.

Using pm.test allows grouping assertions with descriptive names for clear test reports.

This script runs automatically after the request is sent in Postman.

Common Mistakes - 3 Pitfalls

Not checking the response status code

Parsing response body without checking if it is JSON

Hardcoding values inside test scripts without explanation

Bonus Challenge

Now add data-driven testing with 3 different user IDs (1, 2, 3) to verify each returns status 200 and correct user id

Show Hint

Practice

1. What is the main purpose of making a GET request in Postman?

easy

A. To delete data from the server

B. To retrieve data from a server without changing it

C. To send new data to the server

D. To update existing data on the server

Solution

1. Step 1: Understand HTTP methods

   GET is used to request data from a server without modifying it.

2. Step 2: Match method to purpose

   Since GET retrieves data, it does not change or delete anything on the server.

3. Final Answer:

   To retrieve data from a server without changing it -> Option B

4. Quick Check:

   GET = retrieve data [OK]

Hint: GET means get data without changing it [OK]

Common Mistakes:

• Confusing GET with POST or DELETE methods
• Thinking GET changes data on the server
• Assuming GET sends data to the server

2. Which of the following is the correct way to set the HTTP method to GET in Postman?

easy

A. Select GET from the dropdown next to the URL input

B. Type GET in the URL field

C. Add a header named GET

D. Write GET in the request body

Solution

1. Step 1: Locate HTTP method selector in Postman

   Postman has a dropdown menu next to the URL field to choose the HTTP method.

2. Step 2: Choose GET method correctly

   Selecting GET from this dropdown sets the request method properly.

3. Final Answer:

   Select GET from the dropdown next to the URL input -> Option A

4. Quick Check:

   Method dropdown = GET selection [OK]

Hint: Use dropdown near URL to pick GET method [OK]

Common Mistakes:

• Typing GET inside the URL field
• Adding GET as a header instead of method
• Putting GET in the request body

3. You send a GET request to https://api.example.com/users/1 in Postman. The response body is {"id":1,"name":"Alice"} and status code is 200. What does this mean?

medium

A. The request was unauthorized

B. The user with ID 1 was not found

C. There was a server error processing the request

D. The user with ID 1 was found and data returned successfully

Solution

1. Step 1: Interpret status code 200

   Status code 200 means the request was successful and the server returned data.

2. Step 2: Analyze response body content

   The JSON shows user data with id 1 and name Alice, confirming the user was found.

3. Final Answer:

   The user with ID 1 was found and data returned successfully -> Option D

4. Quick Check:

   Status 200 + data = success [OK]

Hint: Status 200 means success with data returned [OK]

Common Mistakes:

• Confusing 200 with error codes like 404 or 500
• Ignoring the response body content
• Assuming 200 means unauthorized access

4. You made a GET request in Postman but got a 404 status code. What is the most likely cause?

medium

A. The server is down

B. You forgot to set the request method to GET

C. The URL endpoint is incorrect or does not exist

D. You sent data in the request body

Solution

1. Step 1: Understand status code 404

   404 means the requested resource was not found on the server.

2. Step 2: Identify common reasons for 404

   Usually caused by wrong URL or endpoint that does not exist.

3. Final Answer:

   The URL endpoint is incorrect or does not exist -> Option C

4. Quick Check:

   404 = resource not found [OK]

Hint: 404 means URL or endpoint is wrong [OK]

Common Mistakes:

• Thinking 404 means server is down
• Assuming method mismatch causes 404
• Believing sending data in GET body causes 404

5. You want to test an API that returns a list of products. Which steps should you follow in Postman to make your first GET request and verify success?

hard

A. Set method to GET, enter the products URL, send request, check status 200 and response data

B. Set method to POST, enter the products URL, add product data in body, send request

C. Set method to DELETE, enter the products URL, send request, check status 204

D. Set method to PUT, enter the products URL, add updated data, send request

Solution

1. Step 1: Choose correct HTTP method for retrieving data

   GET is used to retrieve data like a list of products without changing anything.

2. Step 2: Enter URL and send request

   Input the API endpoint URL for products and send the GET request in Postman.

3. Step 3: Verify response status and data

   Check that status code is 200 (success) and response contains the product list.

4. Final Answer:

   Set method to GET, enter the products URL, send request, check status 200 and response data -> Option A

5. Quick Check:

   GET + URL + 200 status = success [OK]

Hint: GET + URL + check 200 status = first API test [OK]

Common Mistakes:

• Using POST or DELETE instead of GET for retrieval
• Not checking the status code after sending request
• Sending data in GET request body