Use better JUnit API
diff --git a/src/test/java/org/apache/commons/validator/routines/CodeValidatorTest.java b/src/test/java/org/apache/commons/validator/routines/CodeValidatorTest.java
index 48b2e3c..5e35bda 100644
--- a/src/test/java/org/apache/commons/validator/routines/CodeValidatorTest.java
+++ b/src/test/java/org/apache/commons/validator/routines/CodeValidatorTest.java
@@ -51,11 +51,11 @@
         validator = new CodeValidator((String) null, -1, EAN13CheckDigit.EAN13_CHECK_DIGIT);
 
         assertNotNull(validator.getCheckDigit(), "EAN CheckDigit");
-        assertEquals(null, validator.validate(invalidEAN), "EAN CheckDigit invalid");
+        assertNull(validator.validate(invalidEAN), "EAN CheckDigit invalid");
         assertEquals(validEAN, validator.validate(validEAN), "EAN CheckDigit valid");
         assertFalse(validator.isValid(invalidEAN), "EAN CheckDigit (is) invalid");
         assertTrue(validator.isValid(validEAN), "EAN CheckDigit (is) valid");
-        assertEquals(null, validator.validate("978193011099X"), "EAN CheckDigit ex");
+        assertNull(validator.validate("978193011099X"), "EAN CheckDigit ex");
     }
 
     /**
@@ -135,7 +135,7 @@
         validator = new CodeValidator((String) null, 11, -1, (CheckDigit) null);
         assertEquals(11, validator.getMinLength(), "Min 11 - min");
         assertEquals(-1, validator.getMaxLength(), "Min 11 - max");
-        assertEquals(null, validator.validate(length_10), "Min 11 - 10");
+        assertNull(validator.validate(length_10), "Min 11 - 10");
         assertEquals(length_11, validator.validate(length_11), "Min 11 - 11");
         assertEquals(length_12, validator.validate(length_12), "Min 11 - 12");
         assertEquals(length_20, validator.validate(length_20), "Min 11 - 20");
@@ -150,24 +150,24 @@
         assertEquals(length_12, validator.validate(length_12), "Max 21 - 12");
         assertEquals(length_20, validator.validate(length_20), "Max 21 - 20");
         assertEquals(length_21, validator.validate(length_21), "Max 21 - 21");
-        assertEquals(null, validator.validate(length_22), "Max 21 - 22");
+        assertNull(validator.validate(length_22), "Max 21 - 22");
 
         validator = new CodeValidator((String) null, 11, 21, (CheckDigit) null);
         assertEquals(11, validator.getMinLength(), "Min 11 / Max 21 - min");
         assertEquals(21, validator.getMaxLength(), "Min 11 / Max 21 - max");
-        assertEquals(null, validator.validate(length_10), "Min 11 / Max 21 - 10");
+        assertNull(validator.validate(length_10), "Min 11 / Max 21 - 10");
         assertEquals(length_11, validator.validate(length_11), "Min 11 / Max 21 - 11");
         assertEquals(length_12, validator.validate(length_12), "Min 11 / Max 21 - 12");
         assertEquals(length_20, validator.validate(length_20), "Min 11 / Max 21 - 20");
         assertEquals(length_21, validator.validate(length_21), "Min 11 / Max 21 - 21");
-        assertEquals(null, validator.validate(length_22), "Min 11 / Max 21 - 22");
+        assertNull(validator.validate(length_22), "Min 11 / Max 21 - 22");
 
         validator = new CodeValidator((String) null, 11, 11, (CheckDigit) null);
         assertEquals(11, validator.getMinLength(), "Exact 11 - min");
         assertEquals(11, validator.getMaxLength(), "Exact 11 - max");
-        assertEquals(null, validator.validate(length_10), "Exact 11 - 10");
+        assertNull(validator.validate(length_10), "Exact 11 - 10");
         assertEquals(length_11, validator.validate(length_11), "Exact 11 - 11");
-        assertEquals(null, validator.validate(length_12), "Exact 11 - 12");
+        assertNull(validator.validate(length_12), "Exact 11 - 12");
     }
 
     /**
@@ -176,9 +176,9 @@
     @Test
     public void testNoInput() {
         final CodeValidator validator = new CodeValidator((String) null, -1, -1, (CheckDigit) null);
-        assertEquals(null, validator.validate(null), "Null");
-        assertEquals(null, validator.validate(""), "Zero Length");
-        assertEquals(null, validator.validate("   "), "Spaces");
+        assertNull(validator.validate(null), "Null");
+        assertNull(validator.validate(""), "Zero Length");
+        assertNull(validator.validate("   "), "Spaces");
         assertEquals(validator.validate(" A  "), "A", "Trimmed");
     }
 
@@ -207,19 +207,19 @@
         String regex = "^([0-9]{3,4})$";
         validator = new CodeValidator(regex, -1, -1, (CheckDigit) null);
         assertNotNull(validator.getRegexValidator(), "No Regex");
-        assertEquals(null, validator.validate(value2), "Regex 2");
+        assertNull(validator.validate(value2), "Regex 2");
         assertEquals(value3, validator.validate(value3), "Regex 3");
         assertEquals(value4, validator.validate(value4), "Regex 4");
-        assertEquals(null, validator.validate(value5), "Regex 5");
-        assertEquals(null, validator.validate(invalid), "Regex invalid");
+        assertNull(validator.validate(value5), "Regex 5");
+        assertNull(validator.validate(invalid), "Regex invalid");
 
         // Reformatted
         regex = "^([0-9]{3})(?:[-\\s])([0-9]{3})$";
         validator = new CodeValidator(new RegexValidator(regex), 6, (CheckDigit) null);
         assertEquals(validator.validate("123-456"), "123456", "Reformat 123-456");
         assertEquals(validator.validate("123 456"), "123456", "Reformat 123 456");
-        assertEquals(null, validator.validate("123456"), "Reformat 123456");
-        assertEquals(null, validator.validate("123.456"), "Reformat 123.456");
+        assertNull(validator.validate("123456"), "Reformat 123456");
+        assertNull(validator.validate("123.456"), "Reformat 123.456");
 
         regex = "^(?:([0-9]{3})(?:[-\\s])([0-9]{3}))|([0-9]{6})$";
         validator = new CodeValidator(new RegexValidator(regex), 6, (CheckDigit) null);
@@ -233,15 +233,15 @@
     @Test
     public void testValidator294_1() {
         CodeValidator validator = new CodeValidator((String) null, 0, -1, (CheckDigit) null);
-        assertEquals(null, validator.validate(null), "Null");
+        assertNull(validator.validate(null), "Null");
         validator = new CodeValidator((String) null, -1, 0, (CheckDigit) null);
-        assertEquals(null, validator.validate(null), "Null");
+        assertNull(validator.validate(null), "Null");
     }
 
     @Test
     public void testValidator294_2() {
         final CodeValidator validator = new CodeValidator((String) null, -1, 0, (CheckDigit) null);
-        assertEquals(null, validator.validate(null), "Null");
+        assertNull(validator.validate(null), "Null");
     }
 
 }
diff --git a/src/test/java/org/apache/commons/validator/routines/RegexValidatorTest.java b/src/test/java/org/apache/commons/validator/routines/RegexValidatorTest.java
index 1b5923a..be773ee 100644
--- a/src/test/java/org/apache/commons/validator/routines/RegexValidatorTest.java
+++ b/src/test/java/org/apache/commons/validator/routines/RegexValidatorTest.java
@@ -17,8 +17,9 @@
 package org.apache.commons.validator.routines;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotSame;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
@@ -178,9 +179,9 @@
 
         // validate()
         assertEquals(expect, multiple.validate(value), "validate() Multiple");
-        assertEquals(null, single1.validate(value), "validate() 1st");
+        assertNull(single1.validate(value), "validate() 1st");
         assertEquals(expect, single2.validate(value), "validate() 2nd");
-        assertEquals(null, single3.validate(value), "validate() 3rd");
+        assertNull(single3.validate(value), "validate() 3rd");
 
         // match()
         checkArray("match() Multiple", array, multiple.match(value));
@@ -191,8 +192,8 @@
         // All invalid
         value = "AAC*FDE*321";
         assertFalse(multiple.isValid(value), "isValid() Invalid");
-        assertEquals(null, multiple.validate(value), "validate() Invalid");
-        assertEquals(null, multiple.match(value), "match() Multiple");
+        assertNull(multiple.validate(value), "validate() Invalid");
+        assertNull(multiple.match(value), "match() Multiple");
     }
 
     /**
@@ -220,9 +221,9 @@
 
         // validate()
         assertEquals(expect, multiple.validate(value), "Sensitive validate() Multiple");
-        assertEquals(null, single1.validate(value), "Sensitive validate() 1st");
+        assertNull(single1.validate(value), "Sensitive validate() 1st");
         assertEquals(expect, single2.validate(value), "Sensitive validate() 2nd");
-        assertEquals(null, single3.validate(value), "Sensitive validate() 3rd");
+        assertNull(single3.validate(value), "Sensitive validate() 3rd");
 
         // match()
         checkArray("Sensitive match() Multiple", array, multiple.match(value));
@@ -233,8 +234,8 @@
         // All invalid
         value = "AAC*FDE*321";
         assertFalse(multiple.isValid(value), "isValid() Invalid");
-        assertEquals(null, multiple.validate(value), "validate() Invalid");
-        assertEquals(null, multiple.match(value), "match() Multiple");
+        assertNull(multiple.validate(value), "validate() Invalid");
+        assertNull(multiple.match(value), "match() Multiple");
     }
 
     /**
@@ -245,8 +246,8 @@
 
         final RegexValidator validator = new RegexValidator(REGEX);
         assertFalse(validator.isValid(null), "Instance isValid()");
-        assertEquals(null, validator.validate(null), "Instance validate()");
-        assertEquals(null, validator.match(null), "Instance match()");
+        assertNull(validator.validate(null), "Instance validate()");
+        assertNull(validator.match(null), "Instance match()");
     }
 
     /**
@@ -265,9 +266,9 @@
 
         // validate()
         assertEquals(sensitive.validate("ac-DE-1"), "acDE1", "Sensitive validate() valid");
-        assertEquals(null, sensitive.validate("AB-de-1"), "Sensitive validate() invalid");
+        assertNull(sensitive.validate("AB-de-1"), "Sensitive validate() invalid");
         assertEquals(insensitive.validate("AB-de-1"), "ABde1", "Insensitive validate() valid");
-        assertEquals(null, insensitive.validate("ABd-de-1"), "Insensitive validate() invalid");
+        assertNull(insensitive.validate("ABd-de-1"), "Insensitive validate() invalid");
 
         // match()
         checkArray("Sensitive match() valid", new String[] { "ac", "DE", "1" }, sensitive.match("ac-DE-1"));