Do not generate a coverage report when visiting local HTML files with expectBackendCoverageOnly enabled

[kingconan]

Problem:
When visiting a local HTML file (cypress/downloads/test.html), the coverage report is not generated. However, when visiting an external URL like https://docs.cypress.io/app/tooling/code-coverage, the coverage report is successfully generated.

and the error message is code-coverage/test-apps/backend/.nyc_output/out.json has no coverage information Did you forget to instrument your web application?

Cypress Configuration:

const { defineConfig } = require('cypress')

module.exports = defineConfig({
  fixturesFolder: false,
  env: {
    codeCoverage: {
      url: 'http://localhost:3003/__coverage__',
      expectBackendCoverageOnly: true
    },
  },
  e2e: {
    setupNodeEvents(on, config) {
      return require('./cypress/plugins/index.js')(on, config)
    },
    baseUrl: 'http://localhost:3003',
  },
})

Test Spec:

/// <reference types="Cypress" />

context('Converage Test', () => {
  it('backend test', function() {
    cy.visit('/')
    cy.request('/hello')
  })


  it('visit local html file', {baseUrl: null}, () => {
    cy.visit('cypress/downloads/test.html') // failed to generate coverage report
    // cy.visit('https://docs.cypress.io/app/tooling/code-coverage') //Successfully generated the coverage report.
  })
})