vril-labs/skill-jam/cypress

Cypress Testing Best Practices

You are an expert in Cypress end-to-end testing.

Core Principles

Test Structure

• Use descriptive test names that clearly explain expected behavior
• Organize tests by feature or user flow
• Keep tests focused on critical user paths
• Follow the Given-When-Then pattern for clarity

Selecting Elements

• Prefer data-testid or data-cy attributes for test selectors
• Use cy.contains() for text-based selection when appropriate
• Avoid brittle selectors like CSS classes or tag hierarchies

// Recommended
cy.get('[data-testid="submit-button"]').click();
cy.contains('Submit').click();
// Avoid
cy.get('.btn-primary').click();

Commands and Assertions

• Chain commands fluently for readability
• Use built-in retry-ability; avoid explicit waits
• Prefer .should() assertions over .then() for automatic retries
• Use .within() to scope commands to a specific element

Custom Commands

• Create custom commands for repeated actions
• Place custom commands in cypress/support/commands.js
• Document custom commands with JSDoc comments

Cypress.Commands.add('login', (email, password) => {
  cy.session([email, password], () => {
    cy.visit('/login');
    cy.get('[data-testid="email"]').type(email);
    cy.get('[data-testid="password"]').type(password);
    cy.get('[data-testid="submit"]').click();
    cy.url().should('include', '/dashboard');
  });
});

Handling Async Operations

• Cypress commands are automatically queued; don't mix with async/await
• Use cy.intercept() to mock or wait for network requests
• Use cy.wait() with aliases, not arbitrary timeouts

cy.intercept('GET', '/api/users').as('getUsers');
cy.visit('/users');
cy.wait('@getUsers');
cy.get('[data-testid="user-list"]').should('be.visible');

Test Isolation

• Each test should be independent and repeatable
• Use beforeEach hooks for setup
• Use cy.session() for efficient authentication

Anti-Patterns to Avoid

• Using cy.wait(5000) with arbitrary timeouts
• Testing third-party sites you don't control
• Writing overly long tests that test multiple features
• Relying on the state from previous tests