Changed .localize method to need mandatory translations to be passed as second parameter

spec/PKPass.ts

@@ -584,39 +584,60 @@ describe("PKPass", () => {
 
 	describe("localize", () => {
 		it("should fail throw if lang is not a string", () => {
+			// @ts-expect-error
 			expect(() => pass.localize(null)).toThrowError(
 				TypeError,
-				Messages.LANGUAGES.INVALID_TYPE.replace("%s", "object"),
+				Messages.LANGUAGES.INVALID_LANG.replace("%s", "object"),
 			);
 
+			// @ts-expect-error
 			expect(() => pass.localize(undefined)).toThrowError(
 				TypeError,
-				Messages.LANGUAGES.INVALID_TYPE.replace("%s", "undefined"),
+				Messages.LANGUAGES.INVALID_LANG.replace("%s", "undefined"),
 			);
 
 			// @ts-expect-error
 			expect(() => pass.localize(5)).toThrowError(
 				TypeError,
-				Messages.LANGUAGES.INVALID_TYPE.replace("%s", "number"),
+				Messages.LANGUAGES.INVALID_LANG.replace("%s", "number"),
 			);
 
 			// @ts-expect-error
 			expect(() => pass.localize(true)).toThrowError(
 				TypeError,
-				Messages.LANGUAGES.INVALID_TYPE.replace("%s", "boolean"),
+				Messages.LANGUAGES.INVALID_LANG.replace("%s", "boolean"),
 			);
 
 			// @ts-expect-error
 			expect(() => pass.localize({})).toThrowError(
 				TypeError,
-				Messages.LANGUAGES.INVALID_TYPE.replace("%s", "object"),
+				Messages.LANGUAGES.INVALID_LANG.replace("%s", "object"),
 			);
 		});
 
-		it("should create a new language record inside class props", () => {
+		it("should warn developer if no translations have been passed", () => {
+			console.warn = jasmine.createSpy("log");
+			// @ts-expect-error
 			pass.localize("en");
+			pass.localize("en", {});
 
-			expect(pass[localizationSymbol]["en"]).toEqual({});
+			expect(console.warn).toHaveBeenCalledWith(
+				Messages.LANGUAGES.NO_TRANSLATIONS.replace("%s", "en"),
+			);
+
+			expect(console.warn).toHaveBeenCalledTimes(2);
+		});
+
+		it("should create a new language record if some translations are specifies", () => {
+			pass.localize("en", {
+				buon_giorno: "Good Morning",
+				buona_sera: "Good Evening",
+			});
+
+			expect(pass[localizationSymbol]["en"]).toEqual({
+				buon_giorno: "Good Morning",
+				buona_sera: "Good Evening",
+			});
 		});
 
 		it("should accept later translations and merge them with existing ones", () => {
@@ -647,9 +668,13 @@ describe("PKPass", () => {
 		});
 
 		it("should always return undefined", () => {
-			expect(pass.localize("it", undefined)).toBeUndefined();
 			expect(pass.localize("it", null)).toBeUndefined();
-			expect(pass.localize("it", {})).toBeUndefined();
+			expect(
+				pass.localize("it", {
+					say_good_morning: "buongiorno",
+					say_good_evening: "buonasera",
+				}),
+			).toBeUndefined();
 		});
 	});
 

src/PKPass.ts

@@ -669,8 +669,8 @@ export default class PKPass extends Bundle {
 	// ************************** //
 
 	/**
-	 * Allows to specify a language to be added to the
+	 * Allows to add a localization details to the
-	 * final bundle, along with some optionals translations.
+	 * final bundle with some translations.
 	 *
 	 * If the language already exists, translations will be
 	 * merged with the existing ones.
@@ -685,11 +685,11 @@ export default class PKPass extends Bundle {
 
 	public localize(
 		lang: string,
-		translations?: { [key: string]: string } | null,
+		translations: { [key: string]: string } | null,
 	) {
 		if (typeof lang !== "string") {
 			throw new TypeError(
-				formatMessage(Messages.LANGUAGES.INVALID_TYPE, typeof lang),
+				formatMessage(Messages.LANGUAGES.INVALID_LANG, typeof lang),
 			);
 		}
 
@@ -698,6 +698,13 @@ export default class PKPass extends Bundle {
 			return;
 		}
 
+		if (!translations || !Object.keys(translations).length) {
+			console.warn(
+				formatMessage(Messages.LANGUAGES.NO_TRANSLATIONS, lang),
+			);
+			return;
+		}
+
 		this[localizationSymbol][lang] ??= {};
 
 		if (typeof translations === "object" && !Array.isArray(translations)) {

src/messages.ts

@@ -36,6 +36,8 @@ export const DATE = {
 export const LANGUAGES = {
 	INVALID_TYPE:
 		"Cannot set localization. Expected a string for 'lang' but received %s",
+	NO_TRANSLATIONS:
+		"Cannot create or use language %s. If your itention was to just add a language (.lproj) folder to the bundle, both specify some translations or use .addBuffer to add some media.",
 } as const;
 
 export const BARCODES = {