[expect] Fix TypeError in toBeInstanceOf on null or undefined
#6912
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thymikee
approved these changes
Aug 29, 2018
packages/expect/src/matchers.js
Outdated
| @@ -183,7 +183,9 @@ const matchers: MatchersObject = { | |||
| constructor.name || String(constructor), | |||
| )}\n` + | |||
| `Received constructor: ${RECEIVED_COLOR( | |||
| received.constructor && received.constructor.name, | |||
| received !== undefined && received !== null | |||
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received != null will do both the checks
Codecov Report
@@ Coverage Diff @@
## master #6912 +/- ##
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+ Coverage 66.98% 66.98% +<.01%
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Files 250 250
Lines 10365 10360 -5
Branches 4 3 -1
==========================================
- Hits 6943 6940 -3
+ Misses 3421 3419 -2
Partials 1 1
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Pleas update the changelog as well 🙂 |
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@SimenB Ah, thanks for the reminder! |
If using toBeInstanceOf() on an undefined or null value Jest attempts to read `undefined.constructor` which generates an unhelpful error along the lines of "TypeError: Cannot read property 'constructor' of undefined". This fixes the bug so that it's more robust and returns the normal matcher error like "Expected X, received X"
This was referenced Sep 10, 2018
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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. |
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Summary
When using
toBeInstanceOf()on anundefinedornullvalue Jest attempts to useundefined.constructorin its error message, which throws a TypeError along the lines of "TypeError: Cannot read property 'constructor' of undefined"This makes the matcher more robust and returns a normal matcher error along the lines of "Expected X, received X"
Test plan
Also added two snapshot tests for
toBeInstanceOf()forundefinedandnulland confirmed reasonable error messages are now returned for these values.