API versioning validation in Postman

Introduction

API versioning validation helps make sure your app talks to the right version of an API. This avoids errors when the API changes.

When your app needs to work with different API versions at the same time.

When you want to check if the API version in the response matches what you requested.

When you want to prevent your app from breaking after an API update.

When you test backward compatibility of your app with older API versions.

When you want to confirm that deprecated API versions are no longer accessible.

Syntax

Postman

pm.test("API version is correct", function () {
    const responseJson = pm.response.json();
    pm.expect(responseJson.version).to.eql("v1.0");
});

Use pm.response.json() to parse the API response body as JSON.

Use pm.expect() with .to.eql() to check exact equality.

Examples

This checks the API version from the response header instead of the body.

Postman

pm.test("API version is v2", function () {
    const version = pm.response.headers.get('API-Version');
    pm.expect(version).to.eql('v2');
});

This test checks if the version string starts with 'v1' using a regular expression.

Postman

pm.test("API version starts with v1", function () {
    const responseJson = pm.response.json();
    pm.expect(responseJson.version).to.match(/^v1/);
});

Sample Program

This Postman test script checks that the API response JSON has a version field exactly equal to 'v1.0'.

Postman

pm.test("Validate API version in response body", function () {
    const responseJson = pm.response.json();
    pm.expect(responseJson.version).to.eql("v1.0");
});

Important Notes

Always confirm where the API version is returned: in headers or response body.

Use exact matches to avoid confusion between similar versions like 'v1' and 'v10'.

Keep your tests updated when the API versions change or new versions are added.

Summary

API versioning validation ensures your app uses the correct API version.

Check version from response body or headers depending on API design.

Use Postman tests with pm.expect() to verify version values.

Practice

1. What is the main purpose of API versioning validation in Postman?

easy

A. To test the API authentication method

B. To check if the API URL is reachable

C. To verify the API response time

D. To ensure the API response uses the correct version

Solution

1. Step 1: Understand API versioning validation

   API versioning validation checks if the API response matches the expected version.

2. Step 2: Identify the main goal in Postman

   In Postman, this means verifying the version value in the response body or headers.

3. Final Answer:

   To ensure the API response uses the correct version -> Option D

4. Quick Check:

   API version check = Correct version [OK]

Hint: Focus on version correctness in API response [OK]

Common Mistakes:

• Confusing version check with response time
• Checking URL reachability instead of version
• Testing authentication instead of version

2. Which Postman test script correctly asserts that the API version in the response header is 'v2'?

easy

A. pm.response.headers.get('api-version').to.eql('v2');

B. pm.expect(pm.response.headers.get('api-version')).to.eql('v2');

C. pm.expect(pm.response.body.apiVersion).to.eql('v2');

D. pm.expect(pm.response.headers['api-version']).to.equal('v2');

Solution

1. Step 1: Check correct method to get header value

   Use pm.response.headers.get('header-name') to get header value in Postman.

2. Step 2: Use pm.expect() with .to.eql() for assertion

   pm.expect(...).to.eql('v2') correctly asserts the value equals 'v2'.

3. Final Answer:

   pm.expect(pm.response.headers.get('api-version')).to.eql('v2'); -> Option B

4. Quick Check:

   Use headers.get() + pm.expect() [OK]

Hint: Use headers.get() with pm.expect().to.eql() for header checks [OK]

Common Mistakes:

• Using pm.response.headers['api-version'] which is undefined
• Calling to.eql() directly on header getter without pm.expect()
• Checking version in body when question asks for header

3. Given this Postman test script, what will be the test result if the response JSON is {"version": "1.0"}?

pm.test('Check API version', () => {
  pm.expect(pm.response.json().version).to.equal('2.0');
});

medium

A. Test throws syntax error

B. Test passes because version key exists

C. Test fails because version is '1.0', not '2.0'

D. Test passes because .to.equal() ignores value

Solution

1. Step 1: Understand the test assertion

   The test expects the version value to be exactly '2.0'.

2. Step 2: Compare actual response version with expected

   The response has version '1.0', which does not equal '2.0', so assertion fails.

3. Final Answer:

   Test fails because version is '1.0', not '2.0' -> Option C

4. Quick Check:

   Expected '2.0' vs actual '1.0' = Fail [OK]

Hint: Match expected version exactly to pass test [OK]

Common Mistakes:

• Assuming test passes if key exists
• Thinking .to.equal() ignores value differences
• Confusing syntax error with assertion failure

4. You wrote this Postman test to check API version in response header:

pm.test('API version is v1', () => {
  pm.expect(pm.response.headers['api-version']).to.eql('v1');
});

But the test always fails. What is the likely issue?

medium

A. pm.response.headers is not an object with keys, use .get() method instead

B. The header name should be capitalized as 'Api-Version'

C. The assertion method should be .to.equal() not .to.eql()

D. pm.expect() cannot be used for header validation

Solution

1. Step 1: Understand how to access headers in Postman

   pm.response.headers is a special object; headers must be accessed with .get('header-name').

2. Step 2: Identify the error in header access

   Using pm.response.headers['api-version'] returns undefined, causing assertion failure.

3. Final Answer:

   pm.response.headers is not an object with keys, use .get() method instead -> Option A

4. Quick Check:

   Use headers.get() to access headers [OK]

Hint: Use headers.get('name') to access headers in Postman [OK]

Common Mistakes:

• Accessing headers like a normal object
• Changing header name case unnecessarily
• Confusing .to.eql() with .to.equal() causing failure

5. You want to validate that your API supports multiple versions: 'v1', 'v2', or 'v3'. Which Postman test script correctly checks the response header 'api-version' against these allowed versions?

hard

A. pm.test('API version is valid', () => {
const version = pm.response.headers.get('api-version');
pm.expect(version).to.be.oneOf(['v1', 'v2', 'v3']);
});

B. pm.test('API version is valid', () => {
const version = pm.response.headers.get('api-version');
pm.expect(version === 'v1' || 'v2' || 'v3').to.be.true;
});

C. pm.test('API version is valid', () => {
const version = pm.response.headers.get('api-version');
pm.expect(version).to.include(['v1', 'v2', 'v3']);
});

D. pm.test('API version is valid', () => {
const version = pm.response.headers.get('api-version');
pm.expect(version).to.eql('v1' || 'v2' || 'v3');
});

Solution

1. Step 1: Understand how to check multiple allowed values

   pm.expect(...).to.be.oneOf(array) checks if value is in the array.

2. Step 2: Analyze each option's correctness

   pm.test('API version is valid', () => { const version = pm.response.headers.get('api-version'); pm.expect(version).to.be.oneOf(['v1', 'v2', 'v3']); }); uses .to.be.oneOf(['v1','v2','v3']) correctly. pm.test('API version is valid', () => { const version = pm.response.headers.get('api-version'); pm.expect(version).to.include(['v1', 'v2', 'v3']); }); uses .to.include(array) which is invalid. pm.test('API version is valid', () => { const version = pm.response.headers.get('api-version'); pm.expect(version === 'v1' || 'v2' || 'v3').to.be.true; }); uses incorrect boolean logic. pm.test('API version is valid', () => { const version = pm.response.headers.get('api-version'); pm.expect(version).to.eql('v1' || 'v2' || 'v3'); }); uses .to.eql() with || which evaluates incorrectly.

3. Final Answer:

   pm.expect(version).to.be.oneOf(['v1', 'v2', 'v3']); -> Option A

4. Quick Check:

   Use .to.be.oneOf() for multiple allowed values [OK]

Hint: Use .to.be.oneOf() to check multiple valid versions [OK]

Common Mistakes:

• Using .to.include() incorrectly on array
• Writing boolean OR logic inside pm.expect()
• Using .to.eql() with OR operator causing wrong check