Make sure function mocks match original arity #4170
Conversation
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Thanks for sending a PR, including tests. I think to get this merged it needs to be correct and support a variable length. After 10, we could code-gen and use "new Function", what do you think? |
Codecov Report
@@ Coverage Diff @@
## master #4170 +/- ##
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- Coverage 60.55% 60.42% -0.14%
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Files 196 196
Lines 6776 6809 +33
Branches 6 6
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+ Hits 4103 4114 +11
- Misses 2670 2692 +22
Partials 3 3
Continue to review full report at Codecov.
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@cpojer I did attempt this several times. I'm not sure it's possible.. also this is very similar to how sinon solves this issue: https://github.com/sinonjs/sinon/blob/master/lib/sinon/spy.js#L61 |
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We could try-catch for this and fall-back to the solution that doesn't have proper arity. It means it'll work properly in most environments, and fall back to a working solution at least in an environment without eval. |
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@cpojer perhaps the default case should be the same as the 0 case. This way if it's out of range, as you say, it would return a 0 length function like it does right now. |
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@cpojer let me know if my current solution works for you or if I need to make other changes. I'm not sure a dynamic case will work... but if you could point me in the right direction I'm willing to try. |
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Works for me, thank you! |
* Make sure function mocks match original arity * Mocks maintain function arity with 9 or less arguments * Update index.js
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This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs. |
Summary
As reported in #3997, Jest mocks currently do not have the same arity as their underlying functions. This PR attempts to fix that.
Test plan
Run unit tests locally.
Test in a local project using tests provided in issue #3997
Write unit test in jest-mock to ensure arity is set properly