Limit the size of 'actual'/'expected' strings before generating a diff #4638
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juergba
added
type: bug
joielee09
reviewed
Jun 1, 2021
| @@ -164,6 +164,34 @@ describe('Base reporter', function() { | |||
| ' \n actual expected\n \n a foobar inline diff\n ' | |||
| ); | |||
| }); | |||
|
|
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| it("should truncate overly long 'actual' ", function() { | |||
| var actual = ''; | |||
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Hello, I'm trying to contribute to Mocha and before I do I'm trying to get idea of mocha's coding style. I want to know why you used 'var' instea of 'const' or 'let'. Thank you in advance.
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Can this be a feature flag please so it can be disabled? I was having NO speed issues before but not my test output is entirely broken (it doesn't show the actual diff at all) because it's a bit over 2000 characters. |
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Description
Mocha prints its own diff on assertion errors by stringifying
err.actualanderr.expected, then passing both strings to jsdiff for generating a diff-patch. For big strings this synchronous process can take several minutes.jsdiff has some known performance issues, so in mid-term we evtl. should evaluate a jsdiff alternative.
On the other hand it's not a good idea to calculate a diff for two huge strings, even with a faster algorithm. We should limit the size of the input strings, as eg. done by Node's
assertas well.Description of the Change
err.actualanderr.expected... Lines skippedApplicable issues
closes #3675