add globalMocks, remove mocksPattern

[ColCh]

Summary

this is a temporary solution - it's a LOT OF things to be done to adapt "HasteMaps" data structures to understand conception of local/global mocks

but it solves duplicate mock error:

jest-haste-map: duplicate manual mock found:
  Module name: results
  Duplicate Mock path: /project/src/redux/thunks/__mocks__/results.js
This warning is caused by two manual mock files with the same file name.
Jest will use the mock file found in: 
/project/src/redux/thunks/__mocks__/results.js
 Please delete one of the following two files: 
 /project/src/redux/__mocks__/results.js
/project/src/redux/thunks/__mocks__/results.js

I've implemented thing discussed here

#2070 (comment)

#2070 (comment)

Test plan

• tested jest itself with yarn test
• tested our projects with forked version (yarn link). Duplicate mock warning is gone, all our tests have passed. We have mocks for app modules as well as mocks for node_modules

merging this PR should close #2070

[jest-bot]

	Warnings
⚠️	Changes were made to package.json, but not to yarn.lock - Perhaps you need to run `yarn install`?

Generated by 🚫 dangerJS

[codecov-io]

Codecov Report

Merging #2705 into master will increase coverage by 0.08%.

@@            Coverage Diff             @@
##           master    #2705      +/-   ##
==========================================
+ Coverage    67.9%   67.98%   +0.08%     
==========================================
  Files         140      140              
  Lines        5057     5067      +10     
==========================================
+ Hits         3434     3445      +11     
+ Misses       1623     1622       -1

Impacted Files	Coverage Δ
packages/jest-config/src/defaults.js	100% <ø> (ø)	✅
packages/jest-config/src/validConfig.js	100% <ø> (ø)	✅
packages/jest-runtime/src/transform.js	87.87% <ø> (ø)	✅
packages/jest-runtime/src/index.js	86% <ø> (-0.06%)	❌
packages/jest-config/src/normalize.js	86.01% <100%> (+0.4%)	✅
packages/jest-haste-map/src/index.js	95.49% <100%> (+0.12%)	✅
packages/jest-runtime/src/shouldInstrument.js	68.42% <100%> (+1.75%)	✅
packages/pretty-format/src/index.js	98.48% <ø> (+0.5%)	✅

---

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[cpojer]

This is fantastic. Thanks for doing this. I honestly don't think it's that big of a deal!

Here are two suggestions that I think we should do to take it over the finish line:

• Remove "mocksPattern" from everywhere in Jest. It shouldn't be configurable. Make it a constant in jest-haste-map and it should point to "mocks". It was never supposed to be configurable and it just adds unnecessary complexity. If people don't like it, I'm ok if they stop using Jest over it.
• If the mock doesn't match globalMocks, I don't think you need to add it to the haste map at all. jest-runtime/jest-resolve should be able to look for the local mocks already. Can you just try that to confirm my suspicion? I think the jest-haste-map mocks are only really needed at FB.

[cpojer]

Finally, I believe at Facebook we will need to keep allowing all mocks that are currently in the system. Can you think of a way to make it so it can work the same way as it did before? Otherwise we'd have to add hundreds of folders to this config at Facebook.

[ColCh]

I honestly don't think it's that big of a deal!

In case hashmaps structures are used for local mocks too, of course... but they are not :) so it's relatively easy

I don't think you need to add it to the haste map at all. jest-runtime/jest-resolve should be able to look for the local mocks already. Can you just try that to confirm my suspicion?

You're right. Checked against jest tests and our projects tests

Finally, I believe at Facebook we will need to keep allowing all mocks that are currently in the system. Can you think of a way to make it so it can work the same way as it did before? Otherwise we'd have to add hundreds of folders to this config at Facebook.

what about globalMocks: true?

[ColCh]

@cpojer ready to check again. I've added a special undocumented value to force every mock as global:

globalMocks: ['*']

which internally gets translated to globalMocks: true after normalize step.

AFAIK It's not possible to use globalMocks: true in config, because jest-validate simply asserts types of passed in example config, not allowing more than one type for one config entry. Please point, if I'm wrong at this.

[thymikee]

That's right, you can have just one type for user provided config in jest-validate. But there are number of places (e.g. transform) where user config is translated into completely different type. You just need to provide a valid example in jest-config/src/validConfig.js

[peterjacobson]

Hi, I notice it's been two months since this was touched.
My tests are logging warnings:

jest-haste-map: duplicate manual mock found:
  Module name: ErrorUtils
  Duplicate Mock path: /Users/pete/projects/fitadvisor_app/node_modules/react-native/node_modules/fbjs/lib/__mocks__/ErrorUtils.js
This warning is caused by two manual mock files with the same file name.
Jest will use the mock file found in:
/Users/pete/projects/fitadvisor_app/node_modules/react-native/node_modules/fbjs/lib/__mocks__/ErrorUtils.js
 Please delete one of the following two files:
 /Users/pete/projects/fitadvisor_app/node_modules/react-native/Libraries/Core/__mocks__/ErrorUtils.js
/Users/pete/projects/fitadvisor_app/node_modules/react-native/node_modules/fbjs/lib/__mocks__/ErrorUtils.js

Does this PR solve this bug, or has there been another solution in the meantime?

Thanks for all your work @ColCh, and appreciating the clear, kind and constructive way you host this community @cpojer 🥇

[cpojer]

Ok, I think we need to find a different solution to this and we should be looking at it, but haven't had enough time recently to do so. I'll close this PR for now because it is quite outdated at this point.

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