fix(ec/ruc): do not enforce mod-11 check digit on company RUCs

src/ec/ruc.spec.ts

@@ -1,5 +1,9 @@
 import { validate, format } from './ruc';
-import { InvalidLength, InvalidChecksum } from '../exceptions';
+import {
+  InvalidLength,
+  InvalidChecksum,
+  InvalidComponent,
+} from '../exceptions';
 
 describe('ec/ruc', () => {
   it('format:1792060346001', () => {
@@ -29,9 +33,30 @@ describe('ec/ruc', () => {
     expect(result.error).toBeInstanceOf(InvalidLength);
   });
 
-  it('validate:1792060347-001', () => {
-    const result = validate('1792060347-001');
+  // Company RUCs are issued by SRI without a check-digit algorithm, so
+  // numbers that fail the historical mod-11 scheme are still valid.
+  test.each(['1792060347001', '0993381661001', '1760001550001'])(
+    'validate:%s',
+    value => {
+      const result = validate(value);
+
+      expect(result.isValid).toEqual(true);
+    },
+  );
+
+  it('validate:0926687851-001', () => {
+    // Natural-person RUC with an invalid cedula check digit
+    const result = validate('0926687851-001');
 
     expect(result.error).toBeInstanceOf(InvalidChecksum);
   });
+
+  test.each(['0993381661000', '1760001550000', '2593381661001'])(
+    'validate-invalid-component:%s',
+    value => {
+      const result = validate(value);
+
+      expect(result.error).toBeInstanceOf(InvalidComponent);
+    },
+  );
 });

src/ec/ruc.ts

@@ -4,15 +4,21 @@
  * The RUC is a tax identification number for legal entities. It has 13 digits
  * where the third digit is a number denoting the type of entity.
  *
- * Source
+ * Company RUCs (third digit 6 = public, 9 = private/juridical) are issued by
+ * the SRI without any check-digit algorithm, so only structural checks apply
+ * to them; the historical mod-11 scheme rejects real registry-valid numbers.
+ * Cedula-based RUCs (third digit 0-5) do carry the cedula's check digit.
  *
+ * Source
+ *   https://minka.gob.ec/mintel/ge/rutr/gobec_forms/-/issues/32
+ *   https://www.sri.gob.ec/en/web/intersri/consulta-al-ruc
  *
  * TAX/VAT
  */
 
 import * as exceptions from '../exceptions';
 import * as ci from './ci';
-import { strings, weightedSum } from '../util';
+import { strings } from '../util';
 import { Validator, ValidateReturn } from '../types';
 
 function clean(input: string): ReturnType<typeof strings.cleanUnicode> {
@@ -67,39 +73,19 @@ const impl: Validator = {
     }
 
     if (value[2] === '6') {
-      // Public RUC
-      const [front, end] = strings.splitAt(value, 9);
+      // Public RUC: SRI issues these without a check-digit algorithm, so
+      // only the establishment number is checked.
+      const [, end] = strings.splitAt(value, 9);
       if (end === '0000') {
         return { isValid: false, error: new exceptions.InvalidComponent() };
       }
-
-      if (
-        weightedSum(front, {
-          weights: [3, 2, 7, 6, 5, 4, 3, 2, 1],
-          modulus: 11,
-        }) !== 0
-      ) {
-        // If it's not a public, try natural
-        if (end.endsWith('000')) {
-          return { isValid: false, error: new exceptions.InvalidComponent() };
-        }
-
-        return ci.validate(value.substring(0, 10));
-      }
     } else if (value[2] === '9') {
-      // Juridical RUC
-      const [front, end] = strings.splitAt(value, 10);
+      // Juridical RUC: SRI issues these without a check-digit algorithm, so
+      // only the establishment number is checked.
+      const [, end] = strings.splitAt(value, 10);
       if (end === '000') {
         return { isValid: false, error: new exceptions.InvalidComponent() };
       }
-      if (
-        weightedSum(front, {
-          weights: [4, 3, 2, 7, 6, 5, 4, 3, 2, 1],
-          modulus: 11,
-        }) !== 0
-      ) {
-        return { isValid: false, error: new exceptions.InvalidChecksum() };
-      }
     } else {
       return { isValid: false, error: new exceptions.InvalidComponent() };
     }