cypress

Name: cypress
Author: bobmatnyc

Cypress end-to-end and component testing patterns for web apps: reliable selectors, stable waits, network stubbing, auth handling, CI parallelization, and…

INSTALLATION

npx skills add https://github.com/bobmatnyc/claude-mpm-skills --skill cypress

Run in your project or agent environment. Adjust flags if your CLI version differs.

SKILL.md

Cypress (E2E + Component Testing)

Overview

Cypress runs browser automation with first-class network control, time-travel debugging, and a strong local dev workflow. Use it for critical path E2E tests and for component tests when browser-level rendering matters.

Quick Start

Install and open

npm i -D cypress

npx cypress open

Minimal spec

// cypress/e2e/health.cy.ts

describe("health", () => {

  it("loads", () => {

    cy.visit("/");

    cy.contains("Hello").should("be.visible");

  });

});

Core Patterns

1) Stable selectors

Prefer data-testid (or data-cy) attributes for selectors. Avoid brittle CSS chains and text-only selectors for critical interactions.

<button data-testid="save-user">Save</button>

cy.get('[data-testid="save-user"]').click();

2) Deterministic waiting (avoid fixed sleeps)

Wait on app-visible conditions or network aliases rather than cy.wait(1000).

cy.intercept("GET", "/api/users/*").as("getUser");

cy.visit("/users/1");

cy.wait("@getUser");

cy.get('[data-testid="user-email"]').should("not.be.empty");

3) Network control with cy.intercept

Stub responses for deterministic tests and speed. Keep a small set of “real backend” smoke tests separate.

cy.intercept("GET", "/api/users/1", {

  statusCode: 200,

  body: { id: "1", email: "a@example.com" },

}).as("getUser");

4) Authentication strategies

Prefer cy.session to cache login for speed and stability.

// cypress/support/commands.ts

Cypress.Commands.add("login", () => {

  cy.session("user", () => {

    cy.request("POST", "/api/auth/login", {

      email: "test@example.com",

      password: "password",

    });

  });

});

// e2e spec

beforeEach(() => {

  cy.login();

});

Component Testing

Run component tests to validate UI behavior in isolation while keeping browser rendering.

npx cypress open --component

// cypress/component/Button.cy.tsx

import React from "react";

import Button from "../../src/Button";

describe("<Button />", () => {

  it("clicks", () => {

    cy.mount(<Button onClick={cy.stub().as("onClick")}>Save</Button>);

    cy.contains("Save").click();

    cy.get("@onClick").should("have.been.calledOnce");

  });

});

CI Patterns

Artifacts (videos/screenshots)

Store artifacts for failed runs and keep videos optional to reduce storage.

// cypress.config.ts

import { defineConfig } from "cypress";

export default defineConfig({

  video: false,

  screenshotOnRunFailure: true,

  retries: { runMode: 2, openMode: 0 },

});

Parallelization (Cypress Cloud)

Parallelize long E2E suites via Cypress Cloud when runtime dominates feedback loops.

Anti-Patterns

Use cy.wait(1000) as a synchronization mechanism.

Select elements via deep CSS paths.

Mix heavy network stubbing with “real backend” assertions in the same spec.

Depend on test order; isolate state with cy.session and per-test setup.

Troubleshooting

Symptom: flaky click or element not found

Actions:

Add a data-testid hook for the element.

Assert visibility before interaction (should("be.visible")).

Wait on network alias for the data that renders the element.

Symptom: tests fail only in CI