diff --git a/java-strings/src/test/java/com/baeldung/string/StringContainingCharactersUnitTest.java b/java-strings/src/test/java/com/baeldung/string/StringContainingCharactersUnitTest.java
index 75548f4d73..be79103e6b 100644
--- a/java-strings/src/test/java/com/baeldung/string/StringContainingCharactersUnitTest.java
+++ b/java-strings/src/test/java/com/baeldung/string/StringContainingCharactersUnitTest.java
@@ -11,6 +11,8 @@ public class StringContainingCharactersUnitTest {
 
     private static final Pattern[] inputRegexes = new Pattern[4];
 
+    private static final String regex = "^(?=.*?\\p{Lu})(?=.*?\\p{Ll})(?=.*?\\d)(?=.*?[`~!@#$%^&*()\\-_=+\\\\|\\[{\\]};:'\",<.>/?]).*$";
+
     static {
         inputRegexes[0] = Pattern.compile(".*[A-Z].*");
         inputRegexes[1] = Pattern.compile(".*[a-z].*");
@@ -95,4 +97,40 @@ public class StringContainingCharactersUnitTest {
         invalidInput = "b3;";
         assertFalse(checkString(invalidInput));
     }
+
+    @Test
+    public void givenSingleRegex_whenMatchingCorrectString_thenMatches() {
+        String validInput = "Ab3;";
+        assertTrue(Pattern
+          .compile(regex)
+          .matcher(validInput)
+          .matches());
+    }
+
+    @Test
+    public void givenSingleRegex_whenMatchingWrongStrings_thenNotMatching() {
+        String invalidInput = "Ab3";
+        assertFalse(Pattern
+          .compile(regex)
+          .matcher(invalidInput)
+          .matches());
+
+        invalidInput = "Ab;";
+        assertFalse(Pattern
+          .compile(regex)
+          .matcher(invalidInput)
+          .matches());
+
+        invalidInput = "A3;";
+        assertFalse(Pattern
+          .compile(regex)
+          .matcher(invalidInput)
+          .matches());
+
+        invalidInput = "b3;";
+        assertFalse(Pattern
+          .compile(regex)
+          .matcher(invalidInput)
+          .matches());
+    }
 }