path argument is required to res.sendFile leads to "No tests found" error

Current behavior

After running npx cypress open (and starting tests) Cypress runner encounters error below

Terminal shows information:

Desired behavior

Cypress runner “sees” tests and lets me run them.

Test code to reproduce

In pursuit of solution I followed suggestions from issue https://github.com/nrwl/nx/issues/1707, but workarounds stored there didn’t do the trick. Some code:

• cypress.json
• package.json

Cypress Version

8.6.0

Other

No response

[Rainnut]

me too，use [file:preprocessor](https://docs.cypress.io/api/plugins/preprocessors-api#Usage) ts to js

reply

i resolve bug：at plugin/index.js

const registerTasks = require('./plugins')
module.exports = (on, config) =>{
  registerTasks(on, config)
+  return config
};

[OlhaFilatova]

Make sure that callback function for file:preprocessor returns correct result: https://docs.cypress.io/api/plugins/preprocessors-api#The-callback-function-should-return-one-of-the-following a promise that resolves with a path to the compiled file or rejects with error For me this was the reason for such error message. I passed a callback that was calling preprocessor generation inside and returning wrong result.

Example with error:

on("file:preprocessor", () => {
  console.log("FILE PREPROCESSOR");
  webpackPreprocessor(options);
};

Correct example:

on(
  'file:preprocessor',
  webpackPreprocessor(options)
);

Example with console.log:

on("file:preprocessor", async (file) => {
  console.log("FILE PREPROCESSOR");
  return await webpackPreprocessor(options)(file);
});