Reject vowels in SedolCheckDigit

src/main/java/org/apache/commons/validator/routines/checkdigit/SedolCheckDigit.java

@@ -89,9 +89,17 @@ protected int toInt(final char character, final int leftPos, final int rightPos)
         if (charValue > charValueMax || !isAsciiAlphaNum(character)) {
             throw new CheckDigitException("Invalid Character[%d,%d] = '%d' out of range 0 to %d", leftPos, rightPos, charValue, charValueMax);
         }
+        // The SEDOL alphabet omits the vowels A, E, I, O and U, so a code containing one is not a SEDOL.
+        if (isVowel(character)) {
+            throw new CheckDigitException("Invalid Character[%d,%d] = '%c' - vowels are not used in a SEDOL", leftPos, rightPos, character);
+        }
         return charValue;
     }
 
+    private boolean isVowel(final char character) {
+        return "AEIOU".indexOf(Character.toUpperCase(character)) >= 0;
+    }
+
     /**
      * Calculates the <em>weighted</em> value of a character in the code at a specified position.
      *

src/test/java/org/apache/commons/validator/routines/checkdigit/SedolCheckDigitTest.java

@@ -20,6 +20,8 @@
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 
 /**
  * ISIN Check Digit Test.
@@ -51,4 +53,15 @@ void testValidator346() {
         }
     }
 
+    /**
+     * SEDOLs never contain a vowel, yet each of these codes carries a correct modulus 10 check digit with a vowel in
+     * its body, so without the vowel exclusion the check digit alone would accept it. The first five isolate A, E, I,
+     * O and U individually; the remainder combine several.
+     */
+    @ParameterizedTest
+    @ValueSource(strings = { "A000000", "E000006", "I000002", "O000006", "U000000", "B0AKT02", "0EIOU02", "BAEIOU7", "AAAAAA0" })
+    void testVowelsRejected(final String code) {
+        assertFalse(routine.isValid(code), "Should fail (contains a vowel): " + code);
+    }
+
 }