Why running collections validates flows in Postman

Introduction

Running collections helps check if all parts of your API work well together. It shows if the steps flow correctly from one to the next.

When you want to test a full user journey through your API.

When you need to check if data passes correctly between requests.

When you want to find errors in the order of API calls.

When you want to save time by testing many requests at once.

When you want to automate testing to catch problems early.

Syntax

Postman

1. Open Postman.
2. Select a collection.
3. Click 'Run' to open the Collection Runner.
4. Configure environment and iterations.
5. Click 'Start Run' to execute all requests in order.

The collection runner runs requests in the order they appear.

You can add tests in each request to check responses automatically.

Examples

This test checks if the response status is 200 OK.

Postman

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

This test checks if the response JSON contains a userId property.

Postman

pm.test('Response has user id', () => {
    const jsonData = pm.response.json();
    pm.expect(jsonData).to.have.property('userId');
});

Sample Program

This collection runs two requests in order. The first creates a user and saves the user ID. The second gets the user by that ID and checks if it matches. Running the collection validates the flow from creation to retrieval.

Postman

// Assume a collection with two requests: Create User and Get User
// Create User request test script
pm.test('Create user status is 201', () => {
    pm.response.to.have.status(201);
    const jsonData = pm.response.json();
    pm.environment.set('userId', jsonData.id);
});

// Get User request test script
pm.test('Get user status is 200', () => {
    pm.response.to.have.status(200);
    const jsonData = pm.response.json();
    pm.expect(jsonData.id).to.eql(pm.environment.get('userId'));
});

Important Notes

Make sure to set and use environment variables to pass data between requests.

Tests help catch errors early and show which step failed.

Running collections simulates real user flows, so it is very useful for end-to-end testing.

Summary

Running collections tests the full flow of API requests together.

It helps find errors in how requests connect and data moves.

Using tests inside requests makes validation automatic and clear.