fix: test failure b/c of global log level leak

ddtrace/tracer/tracer_test.go

@@ -2126,6 +2126,7 @@ func BenchmarkGenSpanID(b *testing.B) {
 
 // startTestTracer returns a Tracer with a DummyTransport
 func startTestTracer(t testing.TB, opts ...StartOption) (trc *tracer, transport *dummyTransport, flush func(n int), stop func()) {
+	oldLevel := log.GetLevel()
 	transport = newDummyTransport()
 	tick := make(chan time.Time)
 	o := append([]StartOption{
@@ -2160,6 +2161,7 @@ func startTestTracer(t testing.TB, opts ...StartOption) (trc *tracer, transport
 		tracer.Stop()
 		// clear any service name that was set: we want the state to be the same as startup
 		globalconfig.SetServiceName("")
+		log.SetLevel(oldLevel) // avoids test failures because of global state
 	}
 }
 

internal/log/log.go

@@ -65,6 +65,13 @@ func SetLevel(lvl Level) {
 	level = lvl
 }
 
+// GetLevel returns the currrent log level.
+func GetLevel() Level {
+	mu.Lock()
+	defer mu.Unlock()
+	return level
+}
+
 // DebugEnabled returns true if debug log messages are enabled. This can be used in extremely
 // hot code paths to avoid allocating the ...interface{} argument.
 func DebugEnabled() bool {