Path parameters in Postman - Test Execution Trace

Test Overview

This test sends a GET request using Postman with a path parameter to retrieve a specific user's details. It verifies that the response status is 200 and the returned user ID matches the path parameter.

Test Code - Postman

Postman

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

pm.test("Response has correct user ID", function () {
    const userId = pm.variables.get("userId");
    const jsonData = pm.response.json();
    pm.expect(jsonData.id).to.eql(parseInt(userId));
});

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test starts	Postman app is open with the GET request configured to https://api.example.com/users/:userId with userId=5	—	PASS
2	Send GET request to https://api.example.com/users/5	Request sent, waiting for response	—	PASS
3	Receive response with status 200 and JSON body {"id":5, "name":"John Doe"}	Response received in Postman	Check response status is 200	PASS
4	Run test to verify response status code	Test script executes	pm.response.to.have.status(200)	PASS
5	Run test to verify response user ID matches path parameter	Test script executes	pm.expect(jsonData.id).to.eql(5)	PASS

Failure Scenario

Failing Condition: Response status is not 200 or returned user ID does not match the path parameter

Execution Trace Quiz - 3 Questions

What does the test verify first after sending the GET request?

A Request URL contains query parameters

B Response body contains user name

C Response status code is 200

D Response time is less than 1 second

Key Result

Always verify that path parameters are correctly inserted in the request URL and that the response matches the expected data for those parameters.

Practice

1. What is the purpose of path parameters in a URL when testing APIs in Postman?

easy

A. To specify the HTTP method

B. To add headers to the request

C. To make URLs dynamic by allowing variable parts

D. To set the request body content

Solution

1. Step 1: Understand URL structure in APIs

   URLs can have fixed and variable parts. Variable parts are called path parameters.

2. Step 2: Role of path parameters in Postman

   Path parameters allow you to replace parts of the URL dynamically to test different data.

3. Final Answer:

   To make URLs dynamic by allowing variable parts -> Option C

4. Quick Check:

   Path parameters = dynamic URL parts [OK]

Hint: Path parameters make URLs flexible by using placeholders [OK]

Common Mistakes:

• Confusing path parameters with headers
• Thinking path parameters set HTTP methods
• Mixing path parameters with request body

2. Which of the following is the correct syntax to define a path parameter in a Postman request URL?

easy

A. /users/{userId}

B. /users/:userId

C. /users/[userId]

D. /users/<userId>

Solution

1. Step 1: Identify path parameter syntax in Postman

   Postman uses curly braces {} to mark path parameters in URLs.

2. Step 2: Compare options

   Only /users/{userId} uses curly braces correctly: /users/{userId}.

3. Final Answer:

   /users/{userId} -> Option A

4. Quick Check:

   Curly braces = path parameters in Postman [OK]

Hint: Use curly braces {} for path parameters in URLs [OK]

Common Mistakes:

• Using colon : instead of curly braces
• Using square brackets [] or angle brackets <>
• Omitting braces around parameter name

3. Given the Postman request URL https://api.example.com/users/{userId}/posts/{postId} and path parameters userId=42 and postId=7, what is the final URL sent by Postman?

medium

A. https://api.example.com/users/42/posts/7

B. https://api.example.com/users/{42}/posts/{7}

C. https://api.example.com/users/userId/posts/postId

D. https://api.example.com/users/7/posts/42

Solution

1. Step 1: Replace each path parameter with its value

   Replace {userId} with 42 and {postId} with 7 in the URL.

2. Step 2: Construct the final URL

   The URL becomes https://api.example.com/users/42/posts/7 after substitution.

3. Final Answer:

   https://api.example.com/users/42/posts/7 -> Option A

4. Quick Check:

   Substitute parameters correctly = final URL [OK]

Hint: Replace each {param} with its value exactly [OK]

Common Mistakes:

• Leaving curly braces in final URL
• Swapping parameter values
• Using parameter names instead of values

4. You wrote the URL https://api.example.com/items/{itemId} in Postman but forgot to set the path parameter itemId. What will happen when you send the request?

medium

A. Postman removes the {itemId} part from the URL

B. Postman automatically replaces {itemId} with 0

C. Postman prompts you to enter the missing parameter before sending

D. Postman sends the URL with {itemId} unchanged, causing a 404 or error

Solution

1. Step 1: Understand missing path parameter behavior

   If a path parameter is not set, Postman does not replace it automatically.

2. Step 2: Effect on request URL and response

   The URL is sent with {itemId} literally, likely causing server error or 404.

3. Final Answer:

   Postman sends the URL with {itemId} unchanged, causing a 404 or error -> Option D

4. Quick Check:

   Unset path parameter = URL unchanged, error likely [OK]

Hint: Always set all path parameters before sending requests [OK]

Common Mistakes:

• Assuming Postman auto-fills missing parameters
• Expecting Postman to remove missing parameters
• Thinking Postman prompts automatically

5. You want to test an API endpoint /orders/{orderId}/items/{itemId} in Postman. You have a list of order IDs and item IDs. Which approach correctly tests all combinations using path parameters?

hard

A. Manually replace path parameters for each combination and send requests one by one

B. Use Postman collection runner with a CSV file containing orderId and itemId columns

C. Write all URLs with parameters hardcoded and import them as separate requests

D. Use environment variables but only set one parameter at a time

Solution

1. Step 1: Understand testing multiple parameter combinations

   Testing all combinations manually is slow and error-prone.

2. Step 2: Use Postman collection runner with CSV data

   CSV file with columns orderId and itemId lets Postman run requests for each row, replacing path parameters automatically.

3. Final Answer:

   Use Postman collection runner with a CSV file containing orderId and itemId columns -> Option B

4. Quick Check:

   Collection runner + CSV = efficient parameter testing [OK]

Hint: Use collection runner with CSV for multiple path parameter tests [OK]

Common Mistakes:

• Testing combinations manually one by one
• Hardcoding URLs instead of using parameters
• Setting only one parameter in environment variables