cypress-audit Documentation

# Good to know

# Test with a production bundle

Lighthouse is a tool that is supposed to run against a production bundle for computing the performance and best-practices metrics. But it's widely suggested by Cypress to run their test on development environment (opens new window). While this seems a bit counter intuitive, we can rely on the Cypress project feature (opens new window) to run some dedicated test suites against production bundles and to have quick feedbacks (or prevent regression) on these metrics.

# Lighthouse scores may be different between local run and cypress-audit

According to https://github.com/mfrachet/cypress-audit/issues/89, it's possible that cypress-audit provides different Lighthouse results comparing to a local run in a browser. It's important to keep in mind that cypress-audit is just a wrapper around lighthouse. It does not do anything special except calling the regular Lighthouse (opens new window) module through Cypress commands.

To fix this issue, and to get results closer to Lighthouse runs in the browser, you may want to rely on Lighthouse defaults (opens new window) configurations and pass them to cypress-audit.

For instance @maciejtrzcinski in the previous issue suggests to rely on the following configuration in order to have result closer to the run in the browser:

const customThresholds = {
  performance: 90,
};

const desktopConfig = {
  formFactor: "desktop",
  screenEmulation: {
    width: 1350,
    height: 940,
    deviceScaleRatio: 1,
    mobile: false,
    disable: false,
  },
  throttling: {
    rttMs: 40,
    throughputKbps: 11024,
    cpuSlowdownMultiplier: 1,
    requestLatencyMs: 0,
    downloadThroughputKbps: 0,
    uploadThroughputKbps: 0,
  },
};

cy.lighthouse(customThresholds, desktopConfig);

# Session storage

Session storage are supposed to keep data in the current browser tab. Since lighthouse will open a new tab, you won't be able to access the stored data during the audit.

Luckily a community member has created an example on how to make session storage work on https://github.com/olyhaa-aetna/simple-auth-example (opens new window)

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