Default and conditional responses in Postman - Test Execution Trace

Test Overview

This test sends a request to an API endpoint and verifies the response status code and body content. It checks for a default response and a conditional response based on a query parameter.

Test Code - Postman

Postman

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

const jsonData = pm.response.json();
const url = pm.request.url.toString();

pm.test("Response contains default message", function () {
    if (!url.includes("param=hello")) {
        pm.expect(jsonData.message).to.eql("Default response");
    } else {
        pm.expect(true).to.be.true; // Skip if condition not met
    }
});

pm.test("Conditional response when param=hello", function () {
    if (url.includes("param=hello")) {
        pm.expect(jsonData.message).to.eql("Hello response");
    } else {
        pm.expect(true).to.be.true; // Skip if condition not met
    }
});

Execution Trace - 4 Steps

Step	Action	System State	Assertion	Result
1	Send GET request to API endpoint without query parameter	API server is running and ready to respond	Check response status code is 200	PASS
2	Parse JSON response body	Response body received: {"message": "Default response"}	Verify response message equals 'Default response'	PASS
3	Send GET request to API endpoint with query parameter param=hello	API server is running and ready to respond	Check response status code is 200	PASS
4	Parse JSON response body	Response body received: {"message": "Hello response"}	Verify response message equals 'Hello response' when param=hello	PASS

Failure Scenario

Failing Condition: API returns a status code other than 200 or response message does not match expected

Execution Trace Quiz - 3 Questions

What does the test verify when no query parameter is sent?

A Response status code is 404

B Response message is 'Default response'

C Response message is 'Hello response'

D Response body is empty

Key Result

Always verify both the status code and the response body content to ensure the API behaves correctly for default and conditional cases.

Practice

1. What is the main purpose of using default and conditional responses in Postman tests?

easy

A. To send multiple requests at the same time

B. To change the API endpoint dynamically

C. To check different API responses in one test script

D. To automatically generate API documentation

Solution

1. Step 1: Understand the role of conditional responses

   Conditional responses allow testing different API replies based on conditions in one place.

2. Step 2: Identify the main purpose

   This helps verify various outcomes without writing separate tests for each response.

3. Final Answer:

   To check different API responses in one test script -> Option C

4. Quick Check:

   Default and conditional responses = test multiple replies [OK]

Hint: Think: one test script, many response checks [OK]

Common Mistakes:

• Confusing response testing with sending requests
• Assuming it changes API endpoints
• Mixing testing with documentation generation

2. Which of the following is the correct syntax to write a conditional test in Postman to check if the response status is 200?

easy

A. pm.test('Status is 200', () => { if (pm.response.code === 200) { pm.expect(true).to.be.true; } });

B. pm.test('Status is 200', () => { pm.expect(pm.response.code).to.equal(200); });

C. pm.test('Status is 200', () => pm.response.code == 200);

D. pm.test('Status is 200', () => { if (pm.response.status == 200) pm.expect(true); });

Solution

1. Step 1: Review Postman test syntax

   Postman uses pm.test with a callback function and pm.expect for assertions.

2. Step 2: Identify correct assertion for status code

   pm.expect(pm.response.code).to.equal(200) correctly asserts status code equals 200.

3. Final Answer:

   pm.test('Status is 200', () => { pm.expect(pm.response.code).to.equal(200); }); -> Option B

4. Quick Check:

   pm.expect with .to.equal(200) = correct syntax [OK]

Hint: Use pm.expect with .to.equal for exact value checks [OK]

Common Mistakes:

• Using '==' instead of .to.equal() in assertions
• Checking pm.response.status instead of pm.response.code
• Not calling pm.expect properly inside pm.test

3. Given this Postman test code, what will be the test result if the response status is 404?

pm.test('Check response', () => {
  if (pm.response.code === 200) {
    pm.expect(pm.response.json().success).to.be.true;
  } else {
    pm.expect(pm.response.code).to.equal(404);
  }
});

medium

A. Test passes because status is 404 and matches else condition

B. Test fails because success property is missing

C. Test throws an error due to missing JSON body

D. Test passes only if success is true

Solution

1. Step 1: Analyze the if-else condition with status 404

   Status 404 triggers the else block which asserts pm.response.code equals 404.

2. Step 2: Check assertion in else block

   pm.expect(pm.response.code).to.equal(404) will pass since status is 404.

3. Final Answer:

   Test passes because status is 404 and matches else condition -> Option A

4. Quick Check:

   404 status triggers else assertion = pass [OK]

Hint: Match status code to correct if/else branch [OK]

Common Mistakes:

• Assuming test fails due to missing success property
• Thinking JSON parsing fails on 404
• Ignoring else block assertions

4. Identify the error in this Postman test script that checks for a 201 status or a 400 error:

pm.test('Status check', () => {
  if (pm.response.code = 201) {
    pm.expect(pm.response.code).to.equal(201);
  } else if (pm.response.code = 400) {
    pm.expect(pm.response.json().error).to.exist;
  }
});

medium

A. No else block to handle other status codes

B. Missing pm.expect in the first if block

C. Incorrect JSON parsing method

D. Using assignment '=' instead of comparison '===' in if conditions

Solution

1. Step 1: Check if condition syntax

   The code uses '=' which assigns value instead of '===' for comparison.

2. Step 2: Understand impact of assignment in conditions

   Assignment always returns true, causing logic errors and wrong test behavior.

3. Final Answer:

   Using assignment '=' instead of comparison '===' in if conditions -> Option D

4. Quick Check:

   Use '===' for comparisons, not '=' [OK]

Hint: Use '===' for comparisons, '=' is assignment [OK]

Common Mistakes:

• Confusing '=' with '==' or '==='
• Ignoring that assignment returns a value
• Not validating all possible status codes

5. You want to write a Postman test that checks if the response status is 200 and the JSON body has a 'data' field, but if the status is 404, it should check for an 'error' message. Which code snippet correctly implements this conditional response test?

hard

A. pm.test('Conditional response test', () => {
if (pm.response.code === 200) {
pm.expect(pm.response.json().data).to.exist;
} else if (pm.response.code === 404) {
pm.expect(pm.response.json().error).to.exist;
} else {
pm.expect.fail('Unexpected status code');
}
});

B. pm.test('Conditional response test', () => {
pm.expect(pm.response.code === 200 && pm.response.json().data).to.exist;
pm.expect(pm.response.code === 404 && pm.response.json().error).to.exist;
});

C. pm.test('Conditional response test', () => {
if (pm.response.code = 200) {
pm.expect(pm.response.json().data).to.exist;
} else if (pm.response.code = 404) {
pm.expect(pm.response.json().error).to.exist;
}
});

D. pm.test('Conditional response test', () => {
pm.expect(pm.response.json().data || pm.response.json().error).to.exist;
});

Solution

1. Step 1: Check correct use of comparison operators

   pm.test('Conditional response test', () => { if (pm.response.code === 200) { pm.expect(pm.response.json().data).to.exist; } else if (pm.response.code === 404) { pm.expect(pm.response.json().error).to.exist; } else { pm.expect.fail('Unexpected status code'); } }); uses '===' for comparisons correctly. Using '=' causes assignment instead of comparison.

2. Step 2: Verify conditional logic and assertions

   The code checks 'data' field existence for status 200, 'error' for 404, and explicitly fails for unexpected codes using pm.expect.fail().

3. Step 3: Evaluate other options

   One option incorrectly combines status and field checks in single pm.expect statements, causing failures. Another does not condition on status codes at all.

4. Final Answer:

   pm.test('Conditional response test', () => { if (pm.response.code === 200) { pm.expect(pm.response.json().data).to.exist; } else if (pm.response.code === 404) { pm.expect(pm.response.json().error).to.exist; } else { pm.expect.fail('Unexpected status code'); } }); -> Option A

5. Quick Check:

   Use if-else with '===' and proper assertions [OK]

Hint: Use if-else with '===' and separate assertions [OK]

Common Mistakes:

• Using '=' instead of '===' in conditions
• Combining conditions inside one pm.expect
• Not handling unexpected status codes