Support an optional prop to skip luhn algo check in card number validator

.gitignore

@@ -3,3 +3,4 @@ node_modules/
 npm-debug.log
 
 dist
+.idea

CHANGELOG.md

@@ -1,8 +1,11 @@
+# UNRELEASED 
+- Support skipping of luhn check digit validation in card number validator. 
+
 # 9.0.0
 
 - BREAKING CHANGES
   - Update node to v18
--DevDependency Updates:
+    -DevDependency Updates:
   - Update prettier to v3
   - Update eslint-plugin-prettier to v5
 

README.md

@@ -76,6 +76,8 @@ You can optionally pass `maxLength` as a property of an object as a second argum
 
 If a card brand has a normal max length that is shorter than the passed in max length, the validator will use the shorter one. For instance, if a `maxLength` of `16` is provided, the validator will still use `15` as the max length for American Express cards.
 
+You can optionally pass `skipLuhnValidation: true` as a property of an object as a second argument. This will override the default behaviour and will skip the validation of the check digit of the card number using Luhn Algorithm. The `skipLuhnValidation` **should not** be set to `true` in production environment.
+
 ```javascript
 valid.number(<Maestro Card with 19 Digits>, {maxLength: 16});
 

src/__tests__/card-number.ts

@@ -349,4 +349,25 @@ describe("number validates", () => {
       expect(actual.isValid).toBe(true);
     });
   });
+
+  describe("Skip Luhn Validation", () => {
+    const number = "5732806135556590";
+    it("should fail validation for a card with invalid luhn check digit", () => {
+      const actual = cardNumber(number);
+
+      expect(actual.card.type).toBe("maestro");
+      expect(actual.isPotentiallyValid).toBe(true);
+      expect(actual.isValid).toBe(false);
+    });
+
+    it("should succeed validation for a card with invalid luhn check digit when using skipLuhnValidation=true", () => {
+      const actual = cardNumber(number, {
+        skipLuhnValidation: true,
+      });
+
+      expect(actual.card.type).toBe("maestro");
+      expect(actual.isPotentiallyValid).toBe(true);
+      expect(actual.isValid).toBe(true);
+    });
+  });
 });

src/card-number.ts

@@ -2,7 +2,7 @@
 import getCardTypes = require("credit-card-type");
 import type { Verification } from "./types";
 
 // TODO this should probably come from credit-card-type
 type CreditCardType = {
   niceType: string;
   type: string;
@@ -22,6 +22,7 @@
 type CardNumberOptions = {
   maxLength?: number;
   luhnValidateUnionPay?: boolean;
+  skipLuhnValidation?: boolean;
 };
 
 function verification(
@@ -67,8 +68,9 @@
   }
 
   if (
-    cardType.type === getCardTypes.types.UNIONPAY &&
-    options.luhnValidateUnionPay !== true
+    options.skipLuhnValidation === true ||
+    (cardType.type === getCardTypes.types.UNIONPAY &&
+      options.luhnValidateUnionPay !== true)
   ) {
     isValid = true;
   } else {