Opinionated TS transpilation without overrides is problematic

Current behavior:

Cypress recently added better native support for TypeScript, a great step forward, thanks!

However, part of this process added the following defaults for ts-node:

https://github.com/cypress-io/cypress/blob/bdcfe42f790a6f0e73e8f4ae2133c62df2de349d/packages/server/lib/util/ts-node-options.js#L13

Specifically, esModuleInterop is problematic. This is an opinionated transpilation, and cannot be overridden. Typically when working working with a JS / TS mix, you can either use imports such as

import * as Foo from 'foo';

or you can enable esModuleInterop and do

import Foo from 'foo';

In my case, I chose the former, to reduce the “magic” that is done by the TypeScript compiler; however, because Cypress enforces the latter, I get lots of errors along the lines of

TypeError: Foo is not a function

Desired behavior:

A test frameworks authors should not enforce an opinion about how I build my application; this esModuleInterop value should be possible to override. I tried manually changing it by editing the downloaded Cypress JS code in ~/.cache, and the tests ran as expected.

Test code to reproduce

Working on a minimal reproduction, please give me a bit of time 😄

Versions

Cypress: 4.7.0

[bahmutov]

I did move it, but this option was already there https://github.com/cypress-io/cypress/pull/7197/files#diff-0f01b0186fbd767d98bd689a60ddd05aL193

I do wonder if we really need it or not, and if we should overwrite it from the user’s TS config

[sainthkh]

The only block for me is to decide if it’s a breaking change or a bug. If it’s a bug, it can be fixed immediately. If it’s a breaking change, we need to wait for 5.0.