fix: resolve go vet issues and improve test code

- Fix range variable copies lock issue in config_test.go
- Add SetWriter method to Logger for testing
- Fix unused imports in test files
- Update handler.go to resolve unused variable warning
- Ensure all tests pass with go vet checks

Author: takeshi iijima

go-json-server_test.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -13,17 +12,17 @@ import (
 
 func TestMainComponents(t *testing.T) {
 	// This test doesn't run the main function itself but tests key components used by main
-	
+
 	// Create a temporary directory for test files
 	tempDir, err := os.MkdirTemp("", "go-json-server-test")
 	assert.NoError(t, err)
 	defer os.RemoveAll(tempDir)
-	
+
 	// Create a test JSON file for the endpoint
 	jsonFile := filepath.Join(tempDir, "test.json")
 	err = os.WriteFile(jsonFile, []byte(`{"message":"test"}`), 0644)
 	assert.NoError(t, err)
-	
+
 	// Create a test config file
 	configPath := filepath.Join(tempDir, "config.json")
 	configContent := `{
@@ -41,13 +40,13 @@ func TestMainComponents(t *testing.T) {
 	}`
 	err = os.WriteFile(configPath, []byte(configContent), 0644)
 	assert.NoError(t, err)
-	
+
 	// Test loading config
 	cfg, err := config.LoadConfig(configPath)
 	assert.NoError(t, err)
 	assert.Equal(t, 8080, cfg.Port)
 	assert.Equal(t, "info", cfg.LogLevel)
-	
+
 	// Test creating logger
 	logConfig := logger.LogConfig{
 		Level:      logger.ParseLogLevel(cfg.LogLevel),
@@ -57,7 +56,7 @@ func TestMainComponents(t *testing.T) {
 	log, err := logger.NewLogger(logConfig)
 	assert.NoError(t, err)
 	assert.NotNil(t, log)
-	
+
 	// Test config validation
 	err = cfg.Validate()
 	assert.NoError(t, err)

src/config/config.go

@@ -121,7 +121,7 @@ func (c *Config) Reload(path string) error {
 
 	c.mu.Lock()
 	defer c.mu.Unlock()
-	
+
 	c.Host = newConfig.Host
 	c.Port = newConfig.Port
 	c.LogLevel = newConfig.LogLevel
@@ -136,11 +136,11 @@ func (c *Config) Reload(path string) error {
 func (c *Config) GetEndpoints() []Endpoint {
 	c.mu.RLock()
 	defer c.mu.RUnlock()
-	
+
 	// Create a copy to avoid race conditions
 	endpoints := make([]Endpoint, len(c.Endpoints))
 	copy(endpoints, c.Endpoints)
-	
+
 	return endpoints
 }
 
@@ -171,35 +171,35 @@ func WatchConfig(configPath string, config *Config, reloadCh chan<- bool) error
 	if err != nil {
 		return fmt.Errorf("failed to create file watcher: %w", err)
 	}
-	
+
 	go func() {
 		defer watcher.Close()
-		
+
 		dir := filepath.Dir(configPath)
 		if err := watcher.Add(dir); err != nil {
 			fmt.Printf("Error watching directory %s: %v\n", dir, err)
 			return
 		}
-		
+
 		for {
 			select {
 			case event, ok := <-watcher.Events:
 				if !ok {
 					return
 				}
-				
+
 				if event.Name == configPath && (event.Op&fsnotify.Write == fsnotify.Write) {
 					// Add a small delay to wait for write completion
 					time.Sleep(100 * time.Millisecond)
-					
+
 					fmt.Println("Config file changed, reloading...")
 					if err := config.Reload(configPath); err != nil {
 						fmt.Printf("Error reloading config: %v\n", err)
 					} else if reloadCh != nil {
 						reloadCh <- true
 					}
 				}
-				
+
 			case err, ok := <-watcher.Errors:
 				if !ok {
 					return
@@ -208,6 +208,6 @@ func WatchConfig(configPath string, config *Config, reloadCh chan<- bool) error
 			}
 		}
 	}()
-	
+
 	return nil
 }

src/config/config_test.go

@@ -1,11 +1,9 @@
 package config
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
-	"time"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -67,78 +65,95 @@ func TestConfig_Validate(t *testing.T) {
 	err = os.Mkdir(testFolder, 0755)
 	assert.NoError(t, err)
 
-	tests := []struct {
+	type testCase struct {
 		name      string
-		config    Config
+		setupFn   func() Config
 		wantError bool
-	}{
+	}
+
+	tests := []testCase{
 		{
 			name: "Valid config",
-			config: Config{
-				Endpoints: []Endpoint{
-					{Method: "GET", Path: "/test", JsonPath: jsonFile, Status: 200},
-				},
+			setupFn: func() Config {
+				return Config{
+					Endpoints: []Endpoint{
+						{Method: "GET", Path: "/test", JsonPath: jsonFile, Status: 200},
+					},
+				}
 			},
 			wantError: false,
 		},
 		{
 			name: "Valid config with file server",
-			config: Config{
-				Endpoints: []Endpoint{
-					{Path: "/static", Folder: testFolder},
-				},
+			setupFn: func() Config {
+				return Config{
+					Endpoints: []Endpoint{
+						{Path: "/static", Folder: testFolder},
+					},
+				}
 			},
 			wantError: false,
 		},
 		{
 			name: "No endpoints",
-			config: Config{
-				Endpoints: []Endpoint{},
+			setupFn: func() Config {
+				return Config{
+					Endpoints: []Endpoint{},
+				}
 			},
 			wantError: true,
 		},
 		{
 			name: "Empty path",
-			config: Config{
-				Endpoints: []Endpoint{
-					{Method: "GET", Path: "", JsonPath: jsonFile, Status: 200},
-				},
+			setupFn: func() Config {
+				return Config{
+					Endpoints: []Endpoint{
+						{Method: "GET", Path: "", JsonPath: jsonFile, Status: 200},
+					},
+				}
 			},
 			wantError: true,
 		},
 		{
 			name: "Duplicate endpoint",
-			config: Config{
-				Endpoints: []Endpoint{
-					{Method: "GET", Path: "/test", JsonPath: jsonFile, Status: 200},
-					{Method: "GET", Path: "/test", JsonPath: jsonFile, Status: 200},
-				},
+			setupFn: func() Config {
+				return Config{
+					Endpoints: []Endpoint{
+						{Method: "GET", Path: "/test", JsonPath: jsonFile, Status: 200},
+						{Method: "GET", Path: "/test", JsonPath: jsonFile, Status: 200},
+					},
+				}
 			},
 			wantError: true,
 		},
 		{
 			name: "JSON file not found",
-			config: Config{
-				Endpoints: []Endpoint{
-					{Method: "GET", Path: "/test", JsonPath: filepath.Join(tempDir, "notfound.json"), Status: 200},
-				},
+			setupFn: func() Config {
+				return Config{
+					Endpoints: []Endpoint{
+						{Method: "GET", Path: "/test", JsonPath: filepath.Join(tempDir, "notfound.json"), Status: 200},
+					},
+				}
 			},
 			wantError: true,
 		},
 		{
 			name: "Folder not found",
-			config: Config{
-				Endpoints: []Endpoint{
-					{Path: "/static", Folder: filepath.Join(tempDir, "notfound")},
-				},
+			setupFn: func() Config {
+				return Config{
+					Endpoints: []Endpoint{
+						{Path: "/static", Folder: filepath.Join(tempDir, "notfound")},
+					},
+				}
 			},
 			wantError: true,
 		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			err := tt.config.Validate()
+			config := tt.setupFn()
+			err := config.Validate()
 			if tt.wantError {
 				assert.Error(t, err)
 			} else {