How can i type a command with custom Chainable class

[Jialei Jin]

Desire the following to work, but seems commands.ts is not a regular ts module file.

login: (options?: Object) => Chainable<LoginContext>;

[Pierre Criulanscy]

Just add export {} at the top of the files to force it to be considered a valid module :

export {};
declare global {
  namespace Cypress {
    interface Chainable {
      login: () => void;
    }
  }
}
Cypress.Commands.add('login', () => {});