From 6f1903fa66a3a07941b8271a561ae1bfa230c2f1 Mon Sep 17 00:00:00 2001
From: Bojan Zivanovic <bojanz@gmail.com>
Date: Sun, 19 Nov 2023 11:37:32 +0100
Subject: [PATCH] Ensure that an empty locale is always treated the same as
 "en".

This avoids empty output from GetSymbol() or the formatter.
---
 currency.go       | 9 +++++----
 currency_test.go  | 3 ++-
 formatter_test.go | 4 ++++
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/currency.go b/currency.go
index 0b42c9a..276dd62 100644
--- a/currency.go
+++ b/currency.go
@@ -60,7 +60,7 @@ func GetSymbol(currencyCode string, locale Locale) (symbol string, ok bool) {
 	}
 	enLocale := Locale{Language: "en"}
 	enUSLocale := Locale{Language: "en", Territory: "US"}
-	if locale == enLocale || locale == enUSLocale {
+	if locale == enLocale || locale == enUSLocale || locale.IsEmpty() {
 		// The "en"/"en-US" symbol is always first.
 		return symbols[0].symbol, true
 	}
@@ -87,13 +87,14 @@ func GetSymbol(currencyCode string, locale Locale) (symbol string, ok bool) {
 
 // getFormat returns the format for a locale.
 func getFormat(locale Locale) currencyFormat {
-	var format currencyFormat
 	// CLDR considers "en" and "en-US" to be equivalent.
 	// Fall back immediately for better performance
 	enUSLocale := Locale{Language: "en", Territory: "US"}
-	if locale == enUSLocale {
-		locale = Locale{Language: "en"}
+	if locale == enUSLocale || locale.IsEmpty() {
+		return currencyFormats["en"]
 	}
+
+	var format currencyFormat
 	for {
 		localeID := locale.String()
 		if cf, ok := currencyFormats[localeID]; ok {
diff --git a/currency_test.go b/currency_test.go
index 0025528..db86d1e 100644
--- a/currency_test.go
+++ b/currency_test.go
@@ -120,7 +120,8 @@ func TestGetSymbol(t *testing.T) {
 		{"USD", currency.NewLocale("en-AU"), "US$", true},
 		{"USD", currency.NewLocale("es"), "US$", true},
 		{"USD", currency.NewLocale("es-ES"), "US$", true},
-		{"USD", currency.NewLocale(""), "", true},
+		// An empty locale should use "en" data.
+		{"USD", currency.NewLocale(""), "$", true},
 	}
 
 	for _, tt := range tests {
diff --git a/formatter_test.go b/formatter_test.go
index fc510b8..8d87f1d 100644
--- a/formatter_test.go
+++ b/formatter_test.go
@@ -43,6 +43,10 @@ func TestFormatter_Format(t *testing.T) {
 		{"1234.00", "CHF", "de-CH", "CHF\u00a01’234.00"},
 		{"1234.00", "CHF", "sr", "1.234,00\u00a0CHF"},
 
+		// An empty locale should be equivalent to "en".
+		{"1234.59", "USD", "", "$1,234.59"},
+		{"-1234.59", "USD", "", "-$1,234.59"},
+
 		// Arabic digits.
 		{"12345678.90", "USD", "ar", "\u200f١٢٬٣٤٥٬٦٧٨٫٩٠\u00a0US$"},
 		// Arabic extended (Persian) digits.