add test

server/internal/adapter/context_test.go

@@ -9,6 +9,48 @@ import (
 	"golang.org/x/text/language"
 )
 
+func TestAttachLang(t *testing.T) {
+	t.Run("Valid language tag", func(t *testing.T) {
+		ctx := context.Background()
+
+		lang := language.Japanese
+		newCtx := AttachLang(ctx, lang)
+
+		storedLang := newCtx.Value(contextLang)
+
+		assert.NotNil(t, storedLang, "Language should be stored in context")
+		assert.Equal(t, lang, storedLang, "Stored language should match the input")
+	})
+
+	t.Run("Default language (Und)", func(t *testing.T) {
+		ctx := context.Background()
+
+		lang := language.Und
+		newCtx := AttachLang(ctx, lang)
+
+		storedLang := newCtx.Value(contextLang)
+
+		assert.NotNil(t, storedLang, "Language should be stored in context")
+		assert.Equal(t, lang, storedLang, "Stored language should match the input")
+	})
+
+	t.Run("Context chaining", func(t *testing.T) {
+		ctx := context.Background()
+
+		lang1 := language.English
+		ctx1 := AttachLang(ctx, lang1)
+
+		lang2 := language.French
+		ctx2 := AttachLang(ctx1, lang2)
+
+		// confirm that the latest language is stored in the context
+		assert.Equal(t, lang2, ctx2.Value(contextLang), "Latest language should be stored in context")
+
+		// old context is not affected
+		assert.Equal(t, lang1, ctx1.Value(contextLang), "Old context should retain its value")
+	})
+}
+
 func TestLang(t *testing.T) {
 
 	// Default language for testing

server/internal/app/lang.go

@@ -34,9 +34,6 @@ func AttachLanguageMiddleware(next echo.HandlerFunc) echo.HandlerFunc {
 	return func(c echo.Context) error {
 		lang := LanguageExtractor(c.Request())
 		ctx := adapter.AttachLang(c.Request().Context(), lang)
-		if ctx == nil {
-			return echo.NewHTTPError(http.StatusInternalServerError, "Failed to attach language to context")
-		}
 		c.SetRequest(c.Request().WithContext(ctx))
 		return next(c)
 	}

server/internal/locales/locales.go

@@ -29,7 +29,7 @@ type Error struct {
 
 // loadLocales
 // loads locales data from the cache or file
-func loadLocales() {
+func loadLocales(langs []string, localesFileType []string) {
 	cache = NewLocalesCache()
 	for _, lang := range langs {
 		for _, fileType := range localesFileType {
@@ -54,13 +54,15 @@ func loadLocales() {
 // also if key is not found, it will panic
 // because we want to know if the key is not found when server starts
 func LoadError(key ErrorKey) (map[string]*Error, error) {
-	loadOnce.Do(loadLocales)
+	loadOnce.Do(func() {
+		loadLocales(langs, localesFileType)
+	})
 
 	localesError := make(map[string]*Error)
 	for _, lang := range langs {
 		data, ok := cache.GetFromFileCache(lang)
 		if !ok {
-			loadLocales()
+			loadLocales(langs, localesFileType)
 			data, _ = cache.GetFromFileCache(lang)
 		}
 

server/internal/locales/locales_test.go

@@ -3,6 +3,7 @@ package locales
 import (
 	"embed"
 	"fmt"
+	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -11,6 +12,21 @@ import (
 //go:embed en/* ja/*
 var testLocales embed.FS
 
+func TestLoadLocales_FileNotFound(t *testing.T) {
+	cache = nil
+	loadOnce = sync.Once{}
+
+	defer func() {
+		if r := recover(); r != nil {
+			assert.Contains(t, fmt.Sprintf("%v", r), "open aaa/error.json: file does not exist")
+		} else {
+			t.Fatal("Expected panic but it did not occur")
+		}
+	}()
+
+	loadLocales([]string{"aaa"}, []string{"error"})
+}
+
 func TestLoadError(t *testing.T) {
 	// モック用の localesJson を置き換える
 	localesJson = testLocales