Jest: What does "Error: Failed to get mock metadata" mean?

Created on 18 Jan 2016 · 6Comments · Source: facebook/jest

I'm having an error running Jest and would like to get you a simple test case slice as per your guidelines, but am having trouble reproducing it in anything other than my rather large spring boot project.

Could you fill me in on what the error means so that I can better go about reproducing it- or fixing it?

Source

Pinwheeler

👍7

Most helpful comment

@cpojer can you explain more about what "some modules use meta programming" and the reason why they "can't properly be mocket" because right now I face a weird issue, where I get this error when trying to call genMockFromModule on a package built with Babel 7, preset-typescript - but it works if I build the package with Babel 6 and ts-loader. Do you have any idea, what the difference might be?

BruceL33t on 1 Nov 2018

👍17

All 6 comments

jasongonzales23 on 21 Jan 2016

May be related to https://github.com/facebook/jest/pull/682

davidbarton on 22 Jan 2016

Ultimately my issue did boil down to #682 however, the patch doesn't help if the component you are testing imports other components. Super frustrating.

jasongonzales23 on 22 Jan 2016

Yeah, this one is super annoying.

mikecousins on 10 Feb 2016

The error message will link to http://facebook.github.io/jest/docs/manual-mocks.html#content in 0.9.0. Some modules use meta programming and can't properly be mocked. The guide should have examples on how to work around it.

Jest 0.9.0 also has better mocking capabilities, so this issue might go away for your modules.