Fix flaky TestNegativeCases in cometd input (#47698) #47820
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The test was flaky because workerWg.Done() was called before the final
log statement completed, allowing input.Stop() to return while the
goroutine was still logging to the test's logger.
Fix by reordering defers so workerWg.Done() runs last (must be first
defer due to LIFO ordering).
Also fix goroutine leak in the test itself by removing the unnecessary
goroutine and using a select to check for unexpected events.
Difficult to reproduce, run with:
```sh
GOMAXPROCS=1 go test -run TestNegativeCases -count=2000 -failfast ./x-pack/filebeat/input/cometd
```
```
panic: Log in goroutine after TestNegativeCases has completed: 2025-11-28T16:04:01.738+0100 INFO cometd Input worker has stopped. {"pubsub_channel": "channel_name"}
goroutine 8352 [running]:
testing.(*common).log(0xc0002aa000, {0xc0003e9a40?, 0x65?})
/usr/lib/go/src/testing/testing.go:1030 +0x1ac
testing.(*common).Logf(0xc0002aa000, {0x13f435e?, 0x400?}, {0xc00035ddb0?, 0x0?, 0x2?})
/usr/lib/go/src/testing/testing.go:1191 +0x4f
go.uber.org/zap/zaptest.TestingWriter.Write({{0x75eedea33200?, 0xc0002aa000?}, 0x40?}, {0xc0005e5c00?, 0x66, 0xc0005e5c00?})
/home/orestis/go/pkg/mod/go.uber.org/[email protected]/zaptest/logger.go:146 +0xdb
go.uber.org/zap/zapcore.(*ioCore).Write(0xc000136d80, {0x0, {0xc2428c586bfdd61c, 0xafdaba1f1, 0x1d14dc0}, {0x13f6038, 0x6}, {0x140a066, 0x19}, {0x0, ...}, ...}, ...)
/home/orestis/go/pkg/mod/go.uber.org/[email protected]/zapcore/core.go:99 +0xb5
go.uber.org/zap/zapcore.(*CheckedEntry).Write(0xc000251790, {0x0, 0x0, 0x0})
/home/orestis/go/pkg/mod/go.uber.org/[email protected]/zapcore/entry.go:253 +0x119
go.uber.org/zap.(*SugaredLogger).log(0xc000054a98, 0x0, {0x0?, 0x0?}, {0xc0000d5e18?, 0x1?, 0x1?}, {0x0, 0x0, 0x0})
/home/orestis/go/pkg/mod/go.uber.org/[email protected]/sugar.go:355 +0xec
go.uber.org/zap.(*SugaredLogger).Info(...)
/home/orestis/go/pkg/mod/go.uber.org/[email protected]/sugar.go:155
github.com/elastic/elastic-agent-libs/logp.(*Logger).Info(...)
/home/orestis/go/pkg/mod/github.com/elastic/[email protected]/logp/logger.go:186
github.com/elastic/beats/v7/x-pack/filebeat/input/cometd.(*cometdInput).Run.func1.1()
/home/orestis/src/beats/x-pack/filebeat/input/cometd/input.go:77 +0x56d
created by github.com/elastic/beats/v7/x-pack/filebeat/input/cometd.(*cometdInput).Run.func1 in goroutine 8343
/home/orestis/src/beats/x-pack/filebeat/input/cometd/input.go:41 +0x87
FAIL github.com/elastic/beats/v7/x-pack/filebeat/input/cometd 47.249s
FAIL
```
Closes elastic#47698
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Proposed commit message
The test was flaky because workerWg.Done() was called before the final log statement completed, allowing input.Stop() to return while the goroutine was still logging to the test's logger.
Fix by reordering defers so workerWg.Done() runs last (must be first defer due to LIFO ordering).
Also fix goroutine leak in the test itself by removing the unnecessary goroutine and using a select to check for unexpected events.
Checklist
I have made corresponding changes to the documentationI have made corresponding change to the default configuration filesstresstest.shscript to run them under stress conditions and race detector to verify their stability.I have added an entry in./changelog/fragmentsusing the changelog tool.How to test this PR locally
Difficult to reproduce, run with:
GOMAXPROCS=1 go test -run TestNegativeCases -count=2000 -failfast ./x-pack/filebeat/input/cometdRelated issues
Log in goroutine after TestNegativeCases has completed#47698