Next.js example instrumented for code coverage from Cypress tests
npm install
npm run e2eThis starts the application at localhost:3000 and opens Cypress test runner.
Click on the spec file to run the end-to-end tests.
The tests are instrumented following the instructions in Cypress code coverage guide. In particular, the front-end is instrumented using .babelrc file like
{
"presets": ["next/babel"],
"plugins": ["istanbul"]
}When you run tests, the code coverage report is saved in coverage folder. There are reports in several formats, but open the HTML one for human-readable report.
$ open coverage/lcov-report/index.html
To fetch the server-side code coverage, the @cypress/code-coverage plugin needs an endpoint. This endpoint is implemented in pages/api/coverage.js file following the Next.js API convention. This endpoint just returns the existing global coverage object or null
export default (req, res) => {
res.status(200).json({
coverage: global.__coverage__ || null
})
}Cypress plugin requests the right endpoint using the environment variable from cypress.json file
{
"baseUrl": "http://localhost:3000",
"env": {
"codeCoverage": {
"url": "/api/__coverage__"
}
}
}On CI after the tests finish, we store the coverage reports. We also run a script to check if the coverage dropped below 100%
$ npx nyc report --reporter=text-summary --check-coverage --statements 100
================== Coverage summary =========
Statements : 100% ( 22/22 )
Branches : 100% ( 0/0 )
Functions : 100% ( 9/9 )
Lines : 100% ( 22/22 )
=============================================Author: Gleb Bahmutov <gleb.bahmutov@gmail.com> © 2019
License: MIT - do anything with the code, but don't blame me if it does not work.
Support: if you find any problems with this module, email / tweet / open issue on Github
Copyright (c) 2019 Gleb Bahmutov <gleb.bahmutov@gmail.com>
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The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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