Clean up implementation of logging message helper functions

The method signature of logging.Msg() was artificially limiting.
The implementation of logging.Msgf() converted multiple params to an
array instead of passing them through to fmt.Sprintf().

pkg/logging/logging.go

@@ -92,12 +92,12 @@ func (e LogError) Error() string {
 	return e.message
 }
 
-func (l FilteredLogger) Msg(msg string) {
+func (l FilteredLogger) Msg(msg interface{}) {
 	l.Log("msg", msg)
 }
 
 func (l FilteredLogger) Msgf(msg string, args ...interface{}) {
-	l.Msg(fmt.Sprintf(msg, args))
+	l.Msg(fmt.Sprintf(msg, args...))
 }
 
 func (l FilteredLogger) Log(params ...interface{}) error {

pkg/logging/logging_test.go

@@ -1,6 +1,7 @@
 package logging
 
 import (
+	"errors"
 	"kubevirt.io/kubevirt/pkg/api"
 	"path/filepath"
 	"runtime"
@@ -283,3 +284,26 @@ func TestObject(t *testing.T) {
 	assert(t, logEntry[6].(string) == "uid", "Logged line did not contain UUID")
 	tearDown()
 }
+
+func TestError(t *testing.T) {
+	setUp()
+	log := MakeLogger(MockLogger{})
+	log.SetLogLevel(DEBUG)
+	err := errors.New("Test error")
+	log.Error().Log(err)
+	assert(t, logCalled, "Error was not logged via .Log()")
+
+	logCalled = false
+	log.Msg(err)
+	assert(t, logCalled, "Error was not logged via .Msg()")
+
+	logCalled = false
+	// using more than one parameter in format string
+	log.Msgf("[%d] %s", 1, err)
+	assert(t, logCalled, "Error was not logged via .Msgf()")
+
+	logCalled = false
+	log.Msgf("%s", err)
+	assert(t, logCalled, "Error was not logged via .Msgf()")
+	tearDown()
+}