refactor(core): optimize NewCore function and logger initialization

- Remove global defaultLog variable
- Use GetDefaultLogger() directly in NewCore and tests- Initialize defaultLogger with level field in GetDefaultLogger

Author: dapeng

core.go

@@ -53,18 +53,19 @@ func (g *Flag) goneFlag() {}
 // and loads itself as a Goner to enable self-injection.
 // Returns a pointer to the initialized Core.
 func NewCore() *Core {
+	var logger = GetDefaultLogger()
 	loader := Core{
 		nameMap:            make(map[string]*coffin),
 		typeProviderMap:    make(map[reflect.Type]*wrapProvider),
 		typeProviderDepMap: make(map[reflect.Type]*coffin),
 		loaderMap:          make(map[LoaderKey]bool),
-		log:                GetDefaultLogger(),
+		log:                logger,
 	}
 
 	_ = loader.Load(&loader, IsDefault())
 	_ = loader.Load(&ConfigProvider{})
 	_ = loader.Load(&EnvConfigure{}, Name("configure"), IsDefault(new(Configure)), OnlyForName())
-	_ = loader.Load(defaultLog, IsDefault(new(Logger)))
+	_ = loader.Load(logger.(Goner), IsDefault(new(Logger)))
 	return &loader
 }
 

core_test.go

@@ -328,7 +328,7 @@ func TestCore_Fill(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			core := NewCore()
-			_ = core.Load(defaultLog)
+			_ = core.Load(GetDefaultLogger().(Goner))
 			_ = core.Load(&ConfigProvider{})
 			_ = core.Load(&EnvConfigure{}, Name("configure"), IsDefault(new(Configure)), OnlyForName())
 			tt.setup(core)
@@ -379,7 +379,7 @@ func TestCore_Check(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			core := NewCore()
-			_ = core.Load(defaultLog)
+			_ = core.Load(GetDefaultLogger().(Goner))
 			_ = core.Load(&ConfigProvider{})
 			_ = core.Load(&EnvConfigure{}, Name("configure"), IsDefault(new(Configure)), OnlyForName())
 			tt.setup(core)

logger.go

@@ -25,13 +25,10 @@ type Logger interface {
 
 const LoggerName = "gone-logger"
 
-var defaultLog = &defaultLogger{}
-
 func GetDefaultLogger() Logger {
-	if defaultLog == nil {
-		defaultLog = &defaultLogger{}
+	return &defaultLogger{
+		level: new(string),
 	}
-	return defaultLog
 }
 
 type defaultLogger struct {