log4js-node-DEP0004 - Deprecation warning in Angular 12 karma unit tests

Question

I'm getting the following deprecation warning when running unit tests in a brand new Angular 12 application:

(node:14940) [log4js-node-DEP0004] DeprecationWarning: Pattern %d{DATE} is deprecated due to the confusion it causes when used. Please use %d{DATETIME} instead.

why log4js prompts "karma" depends on it. The warning itself is clear as to what should be done but there are two key missing pieces of information:

• it doesn't say when/if the old syntax will stop working
• it doesn't provide a workaround (other than forking karma and replacing the deprecated syntax with the new one - which I'm definitely not going to do).

Downgrading log4js to an earlier version, which doesn't output the warning, using forceResolutions doesn't seem like a good idea, especially since I've found a few github threads related to vulnerabilities in it, although karma doesn't seem to be affected.

The question: are there actionable paths for not getting the warning, or is "and now we wait" (for a karma update) the only option?

Note: I've also asked it on karma's repo.

Answer 1

Got the fix from karma maintainers:

Update karma (in package.json > devDependencies.karma) to ^6.3.12.

Warnings gone. Well done, karma. That was fast!