Added setExpirationDate implementation along with tests

src/PKPass.ts

@@ -256,10 +256,17 @@ export default class PKPass extends Bundle {
 	 * @returns
 	 */
 
-	setExpiration(date: Date | null): this {
-		/**
-		 * @TODO implement
-		 */
+	setExpirationDate(date: Date | null): this {
+		if (date === null) {
+			delete this[propsSymbol]["expirationDate"];
+			return this;
+		}
+
+		const parsedDate = processDate("expirationDate", date);
+
+		if (parsedDate) {
+			this[propsSymbol]["expirationDate"] = parsedDate;
+		}
 
 		return this;
 	}

src/pass.ts

@@ -16,6 +16,7 @@ import {
 	getAllFilesWithName,
 } from "./utils";
 import * as Signature from "./signature";
+import { processDate } from "./processDate";
 
 const barcodeDebug = debug("passkit:barcode");
 const genericDebug = debug("passkit:generic");
@@ -687,18 +688,3 @@ function getValidInArray<T>(
 			Object.keys(current).length && Schemas.isValid(current, schemaName),
 	);
 }
-
-function processDate(key: string, date: Date): string | null {
-	if (!(date instanceof Date)) {
-		return null;
-	}
-
-	const dateParse = dateToW3CString(date);
-
-	if (!dateParse) {
-		genericDebug(formatMessage(DEBUG.DATE_FORMAT_UNMATCH, key));
-		return null;
-	}
-
-	return dateParse;
-}

src/processDate.ts

@@ -0,0 +1,17 @@
+import { dateToW3CString } from "./utils";
+import formatMessage, { ERROR, DEBUG } from "./messages";
+
+export function processDate(key: string, date: Date): string | null {
+	if (!(date instanceof Date)) {
+		return null;
+	}
+
+	const dateParse = dateToW3CString(date);
+
+	if (!dateParse) {
+		console.warn(formatMessage(DEBUG.DATE_FORMAT_UNMATCH, key));
+		return null;
+	}
+
+	return dateParse;
+}