feat(context): accept optional locale

Allow callers to seed Locale directly when constructing a rendering context, while preserving the existing no-argument API.

Co-Authored-By: Virgil <virgil@lethean.io>

context.go

@@ -12,16 +12,26 @@ type Context struct {
 }
 
 // NewContext creates a new rendering context with sensible defaults.
-func NewContext() *Context {
-	return &Context{
+// An optional locale may be provided as the first argument.
+func NewContext(locale ...string) *Context {
+	ctx := &Context{
 		Data: make(map[string]any),
 	}
+	if len(locale) > 0 {
+		ctx.Locale = locale[0]
+	}
+	return ctx
 }
 
 // NewContextWithService creates a rendering context backed by a specific i18n service.
-func NewContextWithService(svc *i18n.Service) *Context {
-	return &Context{
+// An optional locale may be provided as the second argument.
+func NewContextWithService(svc *i18n.Service, locale ...string) *Context {
+	ctx := &Context{
 		Data:    make(map[string]any),
 		service: svc,
 	}
+	if len(locale) > 0 {
+		ctx.Locale = locale[0]
+	}
+	return ctx
 }

node_test.go

@@ -16,6 +16,37 @@ func TestRawNode_Render(t *testing.T) {
 	}
 }
 
+func TestNewContext_Defaults(t *testing.T) {
+	ctx := NewContext()
+	if ctx == nil {
+		t.Fatal("NewContext() returned nil")
+	}
+	if ctx.Locale != "" {
+		t.Errorf("NewContext() Locale = %q, want empty string", ctx.Locale)
+	}
+	if ctx.Data == nil {
+		t.Fatal("NewContext() should initialise Data map")
+	}
+}
+
+func TestNewContext_Locale(t *testing.T) {
+	ctx := NewContext("en-GB")
+	if ctx.Locale != "en-GB" {
+		t.Errorf("NewContext(locale) Locale = %q, want %q", ctx.Locale, "en-GB")
+	}
+}
+
+func TestNewContextWithService_Locale(t *testing.T) {
+	svc, _ := i18n.New()
+	ctx := NewContextWithService(svc, "fr-FR")
+	if ctx.Locale != "fr-FR" {
+		t.Errorf("NewContextWithService(locale) Locale = %q, want %q", ctx.Locale, "fr-FR")
+	}
+	if ctx.service != svc {
+		t.Error("NewContextWithService should retain the provided service")
+	}
+}
+
 func TestElNode_Render(t *testing.T) {
 	ctx := NewContext()
 	node := El("div", Raw("content"))