Timestamp generation in Postman - Build an Automation Script

Generate and verify current timestamp in Postman

Preconditions (2)

Step 1: Open the Postman request

Step 2: Go to the Pre-request Script tab

Step 3: Add script to generate current timestamp in milliseconds

Step 4: Save the script

Step 5: Send the request

Step 6: Go to the Tests tab

Step 7: Add script to verify the timestamp is a number and is recent

Step 8: Send the request again to run the test

✅ Expected Result: The test passes confirming the timestamp is generated correctly and is a recent number

Automation Requirements - Postman Test Scripts

Assertions Needed:

Timestamp is a number

Timestamp is within 5 seconds of current time

Best Practices:

Use pm.variables.set to store timestamp

Use pm.expect for assertions

Keep scripts simple and readable

Automated Solution

Postman

/* Pre-request Script */
const timestamp = Date.now();
pm.variables.set('currentTimestamp', timestamp);

/* Tests Script */
const timestamp = parseInt(pm.variables.get('currentTimestamp'), 10);
pm.test('Timestamp is a number', () => {
    pm.expect(timestamp).to.be.a('number');
});
pm.test('Timestamp is recent', () => {
    const now = Date.now();
    pm.expect(timestamp).to.be.within(now - 5000, now + 5000);
});

In the Pre-request Script, we generate the current timestamp using Date.now() which returns milliseconds since 1970. We store it in a Postman variable currentTimestamp so it can be accessed later.

In the Tests tab, we retrieve the stored timestamp and convert it to a number. We then check two things: first, that it is a number type, and second, that it is within 5 seconds of the current time to ensure it is recent. This confirms the timestamp generation is working correctly.

We use pm.expect for assertions as recommended in Postman scripts. The code is kept simple and clear for easy understanding and maintenance.

Common Mistakes - 3 Pitfalls

Not storing the timestamp in a variable accessible in Tests tab

Using string comparison instead of numeric comparison for timestamp

Not checking if timestamp is recent

Bonus Challenge

Now add data-driven testing with 3 different time offsets (e.g., current time, 1 minute ago, 1 minute ahead) and verify timestamps accordingly

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