Pretty, raw, and preview views in Postman - Build an Automation Script

Verify Pretty, Raw, and Preview response views in Postman

Preconditions (2)

Step 1: Open Postman and create a new GET request

Step 2: Enter the URL https://jsonplaceholder.typicode.com/posts/1

Step 3: Click the Send button

Step 4: Observe the response section

Step 5: Click the Pretty tab and verify the response is formatted and color-coded

Step 6: Click the Raw tab and verify the response is shown as plain text without formatting

Step 7: Click the Preview tab and verify the response is rendered as a web preview (HTML or JSON rendered)

✅ Expected Result: The Pretty view shows formatted and color-coded JSON, the Raw view shows plain text JSON, and the Preview view renders the response appropriately.

Automation Requirements - Postman test scripts

Assertions Needed:

Response status code is 200

Response body is valid JSON

Pretty view shows formatted JSON (simulated by checking JSON parse success)

Raw view matches the exact response text

Preview view renders content-type correctly (simulate by checking headers)

Best Practices:

Use pm.response API for assertions

Validate response status and body before checking views

Avoid hardcoding response text; use dynamic checks

Keep tests independent and clear

Automated Solution

Postman

pm.test('Status code is 200', () => {
    pm.response.to.have.status(200);
});

pm.test('Response body is valid JSON', () => {
    pm.expect(() => pm.response.json()).not.to.throw();
});

pm.test('Raw response matches response text', () => {
    const rawText = pm.response.text();
    pm.expect(rawText).to.be.a('string').and.not.empty;
});

pm.test('Content-Type header is present for preview', () => {
    pm.response.to.have.header('Content-Type');
    const contentType = pm.response.headers.get('Content-Type');
    pm.expect(contentType).to.match(/application\/json|text\//);
});

The first test checks the HTTP status code is 200, confirming the request succeeded.

The second test tries to parse the response body as JSON to simulate the Pretty view, which formats JSON.

The third test verifies the raw response text is a non-empty string, simulating the Raw view showing plain text.

The fourth test checks the Content-Type header to ensure the Preview view can render the response correctly.

These tests use Postman's pm API for clear, maintainable assertions.

Common Mistakes - 3 Pitfalls

Not checking the response status code before parsing JSON

Hardcoding expected raw response text

Ignoring Content-Type header when verifying preview

Bonus Challenge

Now add data-driven testing with 3 different API endpoints to verify Pretty, Raw, and Preview views for each.

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