Why cy.session() for session caching in Cypress? - Purpose & Use Cases

The Big Idea

What if you could skip logging in every time and save minutes on every test run?

The Scenario

Imagine you are testing a website that requires logging in before each test. You open the browser, enter your username and password, wait for the page to load, and then start testing. You repeat this for every single test manually or by writing the same login steps again and again.

The Problem

This manual approach is slow because logging in takes time. It is also error-prone since typing mistakes or network delays can cause tests to fail. Repeating the same steps wastes time and makes your tests longer and harder to maintain.

The Solution

Using cy.session() lets you save the login session once and reuse it for all tests. This means Cypress remembers you are logged in without repeating the login steps every time. Your tests run faster, are more reliable, and easier to write.

Before vs After

✗ Before

beforeEach(() => {
  cy.visit('/login')
  cy.get('#user').type('user')
  cy.get('#pass').type('pass')
  cy.get('button').click()
})

✓ After

beforeEach(() => {
  cy.session('userSession', () => {
    cy.visit('/login')
    cy.get('#user').type('user')
    cy.get('#pass').type('pass')
    cy.get('button').click()
  })
})

What It Enables

You can run many tests quickly and confidently because the login session is cached and reused automatically.

Real Life Example

For example, an e-commerce site test suite logs in once with cy.session() and then tests adding items to the cart, checking out, and viewing order history without logging in again.

Key Takeaways

Manual login before each test is slow and fragile.

cy.session() caches login sessions to speed up tests.

This makes tests faster, more reliable, and easier to maintain.

Practice

1. What is the main purpose of using cy.session() in Cypress tests?

easy

A. To run tests in parallel

B. To clear cookies before each test

C. To cache user sessions and avoid repeated login steps

D. To generate random test data

Solution

1. Step 1: Understand what cy.session() does

   cy.session() caches login or setup steps so tests don't repeat them.

2. Step 2: Identify the main benefit

   This caching speeds up tests by reusing sessions instead of logging in every time.

3. Final Answer:

   To cache user sessions and avoid repeated login steps -> Option C

4. Quick Check:

   Session caching = Avoid repeated logins [OK]

Hint: Remember: cy.session() saves login to speed tests [OK]

Common Mistakes:

• Thinking it clears cookies instead of caching sessions
• Confusing it with parallel test execution
• Assuming it generates test data

2. Which of the following is the correct syntax to create a session with cy.session()?

easy

A. cy.session('user', () => { cy.login() })

B. cy.session('user', cy.login())

C. cy.session('user', function cy.login())

D. cy.session('user', cy.login)

Solution

1. Step 1: Recall cy.session() syntax

   The second argument must be a callback function that runs login steps, e.g., () => { cy.login() }.

2. Step 2: Check each option

   Only cy.session('user', () => { cy.login() }) correctly passes a callback function. The other options pass a function reference incorrectly, execute the function immediately, or use invalid syntax.

3. Final Answer:

   cy.session('user', () => { cy.login() }) -> Option A

4. Quick Check:

   Callback function syntax = cy.session('user', () => { cy.login() }) [OK]

Hint: Use arrow function for session callback: () => { ... } [OK]

Common Mistakes:

• Passing function call instead of function
• Using invalid function syntax
• Omitting the callback wrapper

3. Given the code below, what will be the output in the test run?

cy.session('admin', () => {
  cy.visit('/login')
  cy.get('#username').type('admin')
  cy.get('#password').type('password')
  cy.get('button[type=submit]').click()
})

cy.session('admin', () => {
  cy.visit('/dashboard')
})

medium

A. The login steps run only once; second session reuses cached login

B. Both sessions run login steps twice

C. Second session throws an error because visit is different

D. The test fails due to duplicate session keys

Solution

1. Step 1: Understand session caching behavior

   Sessions with the same key ('admin') cache the first login steps and reuse them in subsequent calls.

2. Step 2: Analyze the second cy.session() call

   The second call with the same key skips login steps and reuses the cached session, so only the visit to '/dashboard' runs.

3. Final Answer:

   The login steps run only once; second session reuses cached login -> Option A

4. Quick Check:

   Same key session = cached login reused [OK]

Hint: Same session key means login runs once only [OK]

Common Mistakes:

• Assuming login runs every time
• Thinking different visits cause errors
• Believing duplicate keys cause test failure

4. Identify the error in the following code using cy.session():

cy.session('user', () => {
  cy.visit('/login')
  cy.get('#user').type('test')
  cy.get('#pass').type('1234')
  cy.get('button').click()
})

cy.session('user', () => {
  cy.visit('/profile')
})

medium

A. The session key 'user' is reused, causing session cache conflict

B. The login callback does not return a promise or chain commands

C. The second session callback should include login steps again

D. No error; code works as expected

Solution

1. Step 1: Check session key usage

   Reusing the same session key 'user' is correct to cache and reuse the session.

2. Step 2: Verify callback structure

   The callback contains Cypress commands chained properly; no need to return a promise explicitly.

3. Step 3: Confirm second session usage

   The second session call reuses the cached session and visits '/profile' without error.

4. Final Answer:

   No error; code works as expected -> Option D

5. Quick Check:

   Reusing session key with proper callback = No error [OK]

Hint: Reusing session key with proper callback is valid [OK]

Common Mistakes:

• Thinking session keys must be unique per call
• Expecting explicit promise return in callback
• Assuming login steps must repeat every time

5. You want to speed up tests by caching sessions but notice some tests fail intermittently due to stale session data. How can you modify cy.session() usage to fix this?

hard

A. Use a different session key for every test to avoid caching

B. Add a validate callback to check session validity before reuse

C. Remove cy.session() and login every time

D. Clear cookies manually before each test instead of using cy.session()

Solution

1. Step 1: Understand stale session problem

   Stale sessions cause intermittent failures because cached data may expire or become invalid.

2. Step 2: Use validate callback in cy.session()

   The validate callback runs before reusing a session to confirm it is still valid, forcing a fresh login if needed.

3. Step 3: Avoid other options

   Using different keys disables caching, removing benefits. Removing cy.session() slows tests. Clearing cookies manually is less efficient.

4. Final Answer:

   Add a validate callback to check session validity before reuse -> Option B

5. Quick Check:

   Validate callback fixes stale session issues [OK]

Hint: Use validate callback to confirm session freshness [OK]

Common Mistakes:

• Disabling caching by changing keys unnecessarily
• Ignoring session validation causing flaky tests
• Removing session caching and slowing tests