Add NATS_LOGGING test helper (#5201)

Setting this environment variable forces NATS Server instances running
in the unit tests to log to stdout. Possible values are:

* `NATS_LOGGING=true go test ...` (or any other non-empty value)
* `NATS_LOGGING=debug go test ...`
* `NATS_LOGGING=trace go test ...`

Signed-off-by: Neil Twigg <neil@nats.io>

server/server_test.go

@@ -35,6 +35,7 @@ import (
 	"testing"
 	"time"
 
+	srvlog "github.com/nats-io/nats-server/v2/logger"
 	"github.com/nats-io/nats.go"
 )
 
@@ -86,6 +87,13 @@ func RunServer(opts *Options) *Server {
 		s.ConfigureLogger()
 	}
 
+	if ll := os.Getenv("NATS_LOGGING"); ll != "" {
+		log := srvlog.NewTestLogger(fmt.Sprintf("[%s] | ", s), true)
+		debug := ll == "debug" || ll == "trace"
+		trace := ll == "trace"
+		s.SetLoggerV2(log, debug, trace, false)
+	}
+
 	// Run server in Go routine.
 	s.Start()
 

test/test.go

@@ -28,6 +28,7 @@ import (
 	"testing"
 	"time"
 
+	srvlog "github.com/nats-io/nats-server/v2/logger"
 	"github.com/nats-io/nats-server/v2/server"
 )
 
@@ -94,6 +95,13 @@ func RunServerCallback(opts *server.Options, callback func(*server.Server)) *ser
 		s.ConfigureLogger()
 	}
 
+	if ll := os.Getenv("NATS_LOGGING"); ll != "" {
+		log := srvlog.NewTestLogger(fmt.Sprintf("[%s] | ", s), true)
+		debug := ll == "debug" || ll == "trace"
+		trace := ll == "trace"
+		s.SetLoggerV2(log, debug, trace, false)
+	}
+
 	if callback != nil {
 		callback(s)
 	}