htlcswitch/hop: add default logger initialization

Without this, running hop tests in isolation panics because the
package's log variable is nil until the parent htlcswitch package
calls UseLogger during init.

Author: calvinrzachman

htlcswitch/hop/log.go

@@ -2,13 +2,28 @@ package hop
 
 import (
 	"github.com/btcsuite/btclog/v2"
+	"github.com/lightningnetwork/lnd/build"
 )
 
+// Subsystem defines the logging sub system name of this package.
+const Subsystem = "HOPS"
+
 // log is a logger that is initialized with no output filters.  This
 // means the package will not perform any logging by default until the caller
 // requests it.
 var log btclog.Logger
 
+// The default amount of logging is none.
+func init() {
+	UseLogger(build.NewSubLogger(Subsystem, nil))
+}
+
+// DisableLog disables all library log output. Logging output is disabled
+// by default until UseLogger is called.
+func DisableLog() {
+	UseLogger(btclog.Disabled)
+}
+
 // UseLogger uses a specified Logger to output package logging info. This
 // function is called from the parent package htlcswitch logger initialization.
 func UseLogger(logger btclog.Logger) {