added test for dns/promise-onlookup.js

[mritunjayz]

test for onlookup promise return of dns/promise
#22471

Checklist

• tests and/or benchmarks are included
• commit message follows commit guidelines

[Trott]

Welcome @mritunjaygoutam12 and thanks for the pull request! Can you indicate what lines in lib/internal/dns/promises.js this covers that aren't already covered by tests in test/internet/test-dns-* and elsewhere? I think this may be best on outdated coverage reports (such as https://coverage.nodejs.org/coverage-9782ce25750f2a34/root/internal/dns/promises.js.html). More recent coverage reports (such as https://coverage.nodejs.org/coverage-988be43e3304be4a/root/internal/dns/promises.js.html) tell a different story (although it would be great to get those last few bits covered).

[mritunjayz]

@Trott Thank you. Now recently I got how to see and understand coverage report. Or one more thing I get confused because there is no test file named for onlookup. I think it was covered by test-dns-lookup.:expressionless::expressionless::expressionless:

[Trott]

If I understand everything correctly, this duplicates existing test functionality so I'm going to close it. If I'm wrong about that, please comment!

@mritunjaygoutam12 Thanks for the pull request. I hope you will try again, perhaps referring to more current coverage stats. Thanks!