Basic authentication in Postman - Test Execution Trace

Test Overview

This test sends a request with Basic Authentication headers to verify the server accepts valid credentials and returns a successful response.

Test Code - Postman

Postman

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

pm.test("Response contains authenticated user info", function () {
    const jsonData = pm.response.json();
    pm.expect(jsonData).to.have.property('authenticated', true);
});

Execution Trace - 7 Steps

Step	Action	System State	Assertion	Result
1	Test starts	Postman is ready to send the request	—	PASS
2	Postman sends HTTP GET request with Basic Auth header (username and password encoded in header)	Request is sent to the server endpoint requiring Basic Authentication	—	PASS
3	Server receives request and validates Basic Auth credentials	Server checks Authorization header for correct username and password	—	PASS
4	Server responds with HTTP 200 status and JSON body indicating authentication success	Response contains status 200 and JSON {"authenticated": true}	Check response status is 200	PASS
5	Postman test script runs assertion to verify status code is 200	Response status code is 200	pm.response.to.have.status(200)	PASS
6	Postman test script runs assertion to verify response JSON has property 'authenticated' set to true	Response JSON contains {"authenticated": true}	pm.expect(jsonData).to.have.property('authenticated', true)	PASS
7	Test ends with all assertions passing	Test report shows pass for all checks	—	PASS

Failure Scenario

Failing Condition: Incorrect or missing Basic Auth credentials cause server to reject request

Execution Trace Quiz - 3 Questions

What does the test verify after sending the request?

A The server returns status 200 and confirms authentication

B The server returns status 404 for missing page

C The server returns status 500 due to error

D The server ignores the Authorization header

Key Result

Always verify that authentication credentials are correctly set and encoded in your test requests to avoid false failures.

Practice

1. What does Basic Authentication in Postman primarily require to access a protected API?

easy

A. A username and password

B. An API key only

C. A token generated by OAuth

D. No credentials, just the URL

Solution

1. Step 1: Understand Basic Authentication

   Basic Authentication requires a username and password to verify identity.

2. Step 2: Identify Postman's method

   Postman uses these credentials to add an Authorization header automatically.

3. Final Answer:

   A username and password -> Option A

4. Quick Check:

   Basic Auth = username + password [OK]

Hint: Basic Auth always needs username and password [OK]

Common Mistakes:

• Confusing Basic Auth with API key or OAuth tokens
• Thinking no credentials are needed
• Using only username or only password

2. Which is the correct way to set Basic Authentication in Postman?

easy

A. Select 'Basic Auth' in the Authorization tab and enter credentials

B. Use the Body tab to send username and password

C. Put credentials in the URL query parameters

D. Add username and password in the Headers tab manually

Solution

1. Step 1: Locate Authorization tab in Postman

   Postman provides an Authorization tab to set authentication types easily.

2. Step 2: Choose Basic Auth and enter credentials

   Selecting Basic Auth lets you enter username and password which Postman encodes automatically.

3. Final Answer:

   Select 'Basic Auth' in the Authorization tab and enter credentials -> Option A

4. Quick Check:

   Use Authorization tab for Basic Auth [OK]

Hint: Use Authorization tab, not Headers or Body [OK]

Common Mistakes:

• Manually adding Authorization header incorrectly
• Putting credentials in URL which is insecure
• Sending credentials in request body for Basic Auth

3. What will Postman send in the Authorization header when you enter username 'user1' and password 'pass123' for Basic Auth?

medium

A. Authorization: Basic user1:pass123

B. Authorization: Bearer user1:pass123

C. Authorization: Basic dXNlcjE6cGFzczEyMw==

D. Authorization: Token dXNlcjE6cGFzczEyMw==

Solution

1. Step 1: Understand Basic Auth header format

   Basic Auth sends 'Authorization: Basic ' plus base64 encoding of 'username:password'.

2. Step 2: Encode 'user1:pass123' in base64

   Encoding 'user1:pass123' results in 'dXNlcjE6cGFzczEyMw=='.

3. Final Answer:

   Authorization: Basic dXNlcjE6cGFzczEyMw== -> Option C

4. Quick Check:

   Basic Auth header = 'Basic ' + base64(username:password) [OK]

Hint: Basic Auth header is 'Basic ' + base64(username:password) [OK]

Common Mistakes:

• Using 'Bearer' instead of 'Basic'
• Sending plain username:password without encoding
• Confusing token or API key formats

4. You set Basic Auth in Postman but get a 401 Unauthorized error. What is the most likely cause?

medium

A. Using HTTPS instead of HTTP

B. Incorrect username or password entered

C. Headers tab is empty

D. Request body is missing

Solution

1. Step 1: Understand 401 Unauthorized meaning

   401 means the server rejected the credentials provided.

2. Step 2: Check credentials correctness

   Most common cause is wrong username or password causing authentication failure.

3. Final Answer:

   Incorrect username or password entered -> Option B

4. Quick Check:

   401 error = bad credentials [OK]

Hint: 401 usually means wrong username or password [OK]

Common Mistakes:

• Thinking HTTPS causes 401 error
• Assuming missing body causes authentication failure
• Ignoring credential typos

5. You want to test an API with Basic Auth but keep your password secure. Which Postman feature helps you avoid exposing your password in the request headers?

hard

A. Write the password directly in the URL

B. Disable SSL verification

C. Send credentials in the request body as plain text

D. Use environment variables to store credentials and reference them

Solution

1. Step 1: Identify secure ways to handle credentials

   Storing credentials in environment variables keeps them hidden and reusable.

2. Step 2: Use variables in Authorization tab

   Referencing variables in Basic Auth fields avoids hardcoding sensitive info in requests.

3. Final Answer:

   Use environment variables to store credentials and reference them -> Option D

4. Quick Check:

   Environment variables protect sensitive data [OK]

Hint: Use environment variables for credentials security [OK]

Common Mistakes:

• Putting password in URL exposes it
• Sending password in body is insecure for Basic Auth
• Disabling SSL reduces security, not protects password