Local storage management in Cypress - Framework Patterns

Framework Mode - Local storage management

Folder Structure

cypress/
├── e2e/                  # Test specs
│   └── localStorage.spec.js
├── support/              # Custom commands and utilities
│   ├── commands.js       # Custom Cypress commands
│   ├── localStorage.js   # Local storage helper functions
│   └── index.js          # Support file loaded before tests
cypress.config.js         # Cypress configuration file

Test Framework Layers

• Test Specs (cypress/e2e): Contains test files that use local storage commands to verify app behavior.
• Support Layer (cypress/support): Holds reusable code like custom commands and helpers for local storage management.
• Configuration (cypress.config.js): Defines environment settings, base URLs, and browser options.

Configuration Patterns

Use cypress.config.js to set base URLs and environment variables for different environments (dev, staging, prod).

Example snippet to set environment variables for local storage keys:

import { defineConfig } from 'cypress'

export default defineConfig({
  e2e: {
    baseUrl: 'https://example.com',
    env: {
      localStorageKey: 'userSession'
    },
    setupNodeEvents(on, config) {
      // implement node event listeners here
    }
  }
})

Use Cypress.env('localStorageKey') in tests and helpers to access keys dynamically.

Test Reporting and CI/CD Integration

• Use Cypress built-in reporters like spec or integrate with mochawesome for detailed HTML reports.
• Configure CI pipelines (GitHub Actions, Jenkins, GitLab CI) to run Cypress tests headlessly and collect reports.
• Store test artifacts such as screenshots and videos on failure for debugging local storage related issues.

Best Practices

1. Use Custom Commands: Create commands like cy.saveLocalStorage() and cy.restoreLocalStorage() to reuse local storage handling code.
2. Isolate Tests: Clear or reset local storage before each test to avoid state leakage.
3. Use Environment Variables: Manage local storage keys and values via config to keep tests flexible.
4. Explicit Assertions: Always assert local storage state after actions to verify expected behavior.
5. Keep Helpers Modular: Put local storage utilities in separate support files for easy maintenance.

Self Check

Where in this folder structure would you add a new helper function to clear specific local storage items before each test?

Key Result

Organize Cypress tests with support helpers and config to manage local storage cleanly and reliably.

Practice

1. What is the primary purpose of local storage in a web browser when testing with Cypress?

easy

A. To run JavaScript code on the server

B. To store small amounts of data persistently for a website

C. To style the webpage dynamically

D. To manage network requests

Solution

1. Step 1: Understand local storage role

   Local storage is used by browsers to save small data like user preferences or tokens persistently.

2. Step 2: Connect with Cypress testing

   Cypress can access this storage to verify or manipulate data during tests.

3. Final Answer:

   To store small amounts of data persistently for a website -> Option B

4. Quick Check:

   Local storage = persistent small data [OK]

Hint: Local storage saves small data for the site, not server tasks [OK]

Common Mistakes:

• Confusing local storage with server-side storage
• Thinking local storage runs code
• Mixing local storage with styling or network

2. Which Cypress command is used to access the browser's window object to manage local storage?

easy

A. cy.document()

B. cy.getLocalStorage()

C. cy.localStorage()

D. cy.window()

Solution

1. Step 1: Recall Cypress commands for browser objects

   To access the browser's window object, Cypress provides cy.window().

2. Step 2: Understand local storage access

   Local storage is a property of the window object, so cy.window() is used to reach it.

3. Final Answer:

   cy.window() -> Option D

4. Quick Check:

   Access window with cy.window() [OK]

Hint: Use cy.window() to reach local storage via window object [OK]

Common Mistakes:

• Using non-existent commands like cy.getLocalStorage()
• Confusing cy.document() with window object
• Assuming cy.localStorage() exists

3. What will be the output of the following Cypress code snippet?

cy.window().then(win => {
  win.localStorage.setItem('user', 'Alice');
  const user = win.localStorage.getItem('user');
  cy.wrap(user).should('equal', 'Alice');
});

medium

A. Test will fail due to syntax error in setItem usage

B. Test will fail because localStorage is not accessible

C. Test will pass because 'user' is set and retrieved correctly

D. Test will pass but 'user' will be undefined

Solution

1. Step 1: Analyze localStorage set and get

   The code sets 'user' key to 'Alice' in localStorage, then retrieves it correctly.

2. Step 2: Check assertion correctness

   The assertion checks if retrieved value equals 'Alice', which is true, so test passes.

3. Final Answer:

   Test will pass because 'user' is set and retrieved correctly -> Option C

4. Quick Check:

   Set and get localStorage works, test passes [OK]

Hint: Setting then getting localStorage key returns correct value [OK]

Common Mistakes:

• Assuming localStorage is inaccessible in Cypress
• Thinking setItem syntax is wrong
• Expecting undefined instead of stored value

4. Identify the error in this Cypress code that tries to clear local storage:

cy.window().then(win => {
  win.localStorage.clear;
});

medium

A. Missing parentheses to call clear method

B. localStorage.clear requires a key argument

C. cy.window() cannot access localStorage

D. clear is not a function of localStorage

Solution

1. Step 1: Check localStorage clear usage

   localStorage.clear is a function and must be called with parentheses: clear()

2. Step 2: Identify missing parentheses error

   The code uses clear without parentheses, so it does not execute the function.

3. Final Answer:

   Missing parentheses to call clear method -> Option A

4. Quick Check:

   Call clear() with parentheses to clear storage [OK]

Hint: Always add () to call localStorage.clear() method [OK]

Common Mistakes:

• Forgetting parentheses when calling functions
• Thinking clear needs a key argument
• Assuming cy.window() can't access localStorage

5. You want to write a Cypress test that saves a token in local storage, reloads the page, and then verifies the token is still present. Which sequence of commands correctly achieves this?

hard

A. cy.window().then(win => win.localStorage.setItem('token', 'abc123')); cy.reload(); cy.window().then(win => expect(win.localStorage.getItem('token')).to.equal('abc123'));

B. cy.setLocalStorage('token', 'abc123'); cy.reload(); cy.getLocalStorage('token').should('equal', 'abc123');

C. cy.window().then(win => win.localStorage.setItem('token', 'abc123')); cy.reload(); cy.window().its('localStorage.token').should('equal', 'abc123');

D. cy.window().then(win => win.localStorage.clear()); cy.reload(); cy.window().its('localStorage.token').should('be.null');

Solution

1. Step 1: Save token in localStorage correctly

   Using cy.window().then(win => win.localStorage.setItem('token', 'abc123')) correctly sets the token.

2. Step 2: Reload and verify token presence

   After cy.reload(), accessing localStorage via cy.window().then and asserting with expect ensures token is still 'abc123'.

3. Step 3: Evaluate other options

   cy.window().then(win => win.localStorage.setItem('token', 'abc123')); cy.reload(); cy.window().its('localStorage.token').should('equal', 'abc123'); uses incorrect property access for localStorage token; cy.setLocalStorage('token', 'abc123'); cy.reload(); cy.getLocalStorage('token').should('equal', 'abc123'); uses non-existent commands; cy.window().then(win => win.localStorage.clear()); cy.reload(); cy.window().its('localStorage.token').should('be.null'); clears storage and checks for null, which is not the goal.

4. Final Answer:

   Use cy.window() to set, reload, then check with expect -> Option A

5. Quick Check:

   Set, reload, then assert with cy.window() and expect [OK]

Hint: Set token, reload, then check with cy.window() and expect [OK]

Common Mistakes:

• Using wrong localStorage property access
• Using non-existent Cypress commands
• Clearing storage instead of verifying token