Testing to receive mail with Cypress and Node-imap fails with missing 'net' module

Question

I want to use node-imap or the imap package from NPM in Cypress to check whether certain E-mails are received and to check their contents.

When I try a basic copy from the example taken from the imap github and docs it fails with the following error:

./node_modules/imap/lib/Connection.js
Module not found: Error: Can't resolve 'net' in '/Users/username/Documents/test-e2e/node_modules/imap/lib'
resolve 'net' in '/Users/username/Documents/test-e2e/node_modules/imap/lib'
  Parsed request is a module
  using description file: /Users/username/Documents/test-e2e/node_modules/imap/package.json (relative path: ./lib)
    Field 'browser' doesn't contain a valid alias configuration
    resolve as module
      /Users/username/Documents/test-e2e/node_modules/imap/lib/node_modules doesn't exist or is not a directory
      /Users/username/Documents/test-e2e/node_modules/node_modules doesn't exist or is not a directory
      /Users/username/Documents/node_modules doesn't exist or is not a directory
      /Users/username/node_modules doesn't exist or is not a directory
      /Users/node_modules doesn't exist or is not a directory
      /node_modules doesn't exist or is not a directory
      looking for modules in /Users/username/Documents/test-e2e/node_modules/imap/node_modules
        using description file: /Users/username/Documents/test-e2e/node_modules/imap/package.json (relative path: ./node_modules)
          Field 'browser' doesn't contain a valid alias configuration
      looking for modules in /Users/username/Documents/test-e2e/node_modules
        using description file: /Users/username/Documents/test-e2e/package.json (relative path: ./node_modules)
          Field 'browser' doesn't contain a valid alias configuration
          using description file: /Users/username/Documents/test-e2e/node_modules/imap/package.json (relative path: ./node_modules/net)
            no extension
              Field 'browser' doesn't contain a valid alias configuration
          using description file: /Users/username/Documents/test-e2e/package.json (relative path: ./node_modules/net)
            no extension
              Field 'browser' doesn't contain a valid alias configuration
              /Users/username/Documents/test-e2e/node_modules/imap/node_modules/net doesn't exist
            .ts
              Field 'browser' doesn't contain a valid alias configuration
              /Users/username/Documents/test-e2e/node_modules/net doesn't exist
            .ts
              Field 'browser' doesn't contain a valid alias configuration
              /Users/username/Documents/test-e2e/node_modules/imap/node_modules/net.ts doesn't exist
            .js
              Field 'browser' doesn't contain a valid alias configuration
              /Users/username/Documents/test-e2e/node_modules/net.ts doesn't exist
            .js
              Field 'browser' doesn't contain a valid alias configuration
              /Users/username/Documents/test-e2e/node_modules/imap/node_modules/net.js doesn't exist
              /Users/username/Documents/test-e2e/node_modules/net.js doesn't exist
            as directory
              /Users/username/Documents/test-e2e/node_modules/imap/node_modules/net doesn't exist
            as directory
              /Users/username/Documents/test-e2e/node_modules/net doesn't exist

No tests can run because of this. I tried looking for this 'net', also in combination with the imap package, but I can't really find any solution for this. Is it even possible to use Imap with Cypress?

score 4 · Accepted Answer · answered Dec 13 '19 at 22:34

Cypress executes it's code within the browser. So you can not use such NPM modules. To solve this prpblem, you must use cy.task. Cypress executes tasks within a node process and thus you can use any lib you want. The tasks must be defined in the plugins file because this file is loaded in the node context.

So you have to tell cypress in the cypress.json that you are using a plugins file:

{
    ...
    "pluginsFile": "cypress/plugins/plugins.js",
    ...
  }

Then define a task in plugins.js:

on('task', {
    sendMail({ subject, to, body }) {
      return getEmail(subject, to, body);
    }
  });

getEmail should be your example code.

Use the task like this:

cy.task("sendMail", { subject, to, body }, { timeout: 30000 });

Additional info: > As of Cypress version 10.0.0, you will need to add your plugin to the setupNodeEvents function in the Cypress configuration ( https://docs.cypress.io/guides/tooling/plugins-guide#Using-a-plugin ) — David, Mar 29 '23 at 09:39

Testing to receive mail with Cypress and Node-imap fails with missing 'net' module

1 Answers1