Mocking functions of jest not working (need to babel-jest)

[Bnaya]

For the modules mocking of jest to work with babel, they made special babel preset to hoist the calls above the require() calls
https://www.npmjs.com/package/babel-plugin-jest-hoist

In order to make ts-jest work properly as babel-jest we need this transformation also.

[kulshekhar]

I can't commit to this as there's a lot on my plate right now. I'd be open to a PR with tests though :)

[tkrotoff]

Related comment here:

[...] When using babel-jest, we actually hoist unmock calls above imports. If you are using TypeScript, we don't have this custom transform available unfortunately.

Here are a few ways to work around this issue:

• [...]
• [...]
• Use babel-jest in your typescript preprocessor after processing your typescript code into JS. (basically: return babelJest.process(tsOutput, filename); ).
• [...]

Found this https://github.com/lozinsky/typescript-babel-jest that does exactly that: https://github.com/lozinsky/typescript-babel-jest/blob/234de0a5832f85061115655959339e7ee055663c/source/preprocessor.js#L23

[bhouser]

Why is this closed? Is the problem solved, because I'm having issues mocking Typescript imports.

[kulshekhar]

@bhouser I'm not sure why this was closed. If you're facing this exact issue, I can reopen it

[bhouser]

@kulshekhar I'm having exactly this issue yes. Typescript imports are not mocked, jest.mock('module') calls have no effect. I can't guarantee that I don't have any other issues in my code, but if the mock commands are not hoisted above the import statements, I don't see how this jest feature can work.

[bhouser]

I had another look at this issue, and I've found a solution. Hoisting of jest.mock statements above import statements works, but with a caveat: apparently the jest.mock statement won't be hoisted if it's not already above the import statement in the original code.

This works:

jest.mock('../pleaseMockMe')
import { iHaveBeenMocked } from '../pleaseMockMe'

This does not work:

import { iHaveBeenMocked } from '../pleaseMockMe'
jest.mock('../pleaseMockMe')

So I wouldn't say that jest.mock statements are hoisted above typescript import statements, but rather, typescript import statements are hoisted, but not above jest.mock statements.

@kulshekhar I think you can close this issue again, sorry about that.

[kulshekhar]

@bhouser no problem! Hopefully others facing this issue will be able to use the workaround you've posted 😄

[tkrotoff]

@kulshekhar this shouldn't be closed until the workaround is documented in README.md: this will save others a lot of troubles

[kulshekhar]

@tkrotoff fair enough.

Would it be possible for you to submit a PR?