Base fixes and test harness

PortfolioJournal/Utilities/CurrencyFormatter.swift

@@ -6,6 +6,16 @@ enum CurrencyFormatter {
         return AppSettings.getOrCreate(in: context).currency
     }
 
+    static func locale(for currencyCode: String?) -> Locale {
+        guard let currencyCode, !currencyCode.isEmpty else { return Locale.current }
+        if let match = Locale.availableIdentifiers.first(where: {
+            Locale(identifier: $0).currency?.identifier == currencyCode
+        }) {
+            return Locale(identifier: match)
+        }
+        return Locale.current
+    }
+
     static func format(_ decimal: Decimal, style: NumberFormatter.Style = .currency, maximumFractionDigits: Int = 2) -> String {
         let formatter = NumberFormatter()
         formatter.numberStyle = style
@@ -14,6 +24,21 @@ enum CurrencyFormatter {
         return formatter.string(from: decimal as NSDecimalNumber) ?? "\(decimal)"
     }
 
+    static func format(
+        _ decimal: Decimal,
+        currencyCode: String?,
+        style: NumberFormatter.Style = .currency,
+        maximumFractionDigits: Int = 2,
+        preferredLocale: Locale? = nil
+    ) -> String {
+        let formatter = NumberFormatter()
+        formatter.numberStyle = style
+        formatter.currencyCode = currencyCode ?? currentCurrencyCode()
+        formatter.maximumFractionDigits = maximumFractionDigits
+        formatter.locale = preferredLocale ?? locale(for: currencyCode)
+        return formatter.string(from: decimal as NSDecimalNumber) ?? "\(decimal)"
+    }
+
     static func symbol(for code: String) -> String {
         let formatter = NumberFormatter()
         formatter.numberStyle = .currency