Limitations of Online Regex Checkers in MuleSoft

To ensure your regex patterns behave as expected within a Mule application, use one of the following methods for testing and validation:

1. Use an Updated Regex: If your input string contains a newline, update your regex to allow for it. For example, using [\s\S]* is a common way to match any character, including newlines.

2. Escape the Input: If you can't modify the regex, you can escape the newline characters in the input string. Change \n to \\n. This will cause the newline to be treated as a literal two-character sequence, which the original regex may then be able to validate successfully.

3. Test in Mulesoft-Specific Environments: The most reliable way to validate a regex for Mulesoft is to test it in an environment that uses the same regex engine. We recommend using the DataWeave Playground  or creating a simple standalone Java program. Below is a sample code snippet that you can use to replicate the behavior and confirm the expected outcome.

   /*sample Code*/
   
   import java.util.regex.Matcher;
   import java.util.regex.Pattern;
   
   public class Main 
   {
       public static void main(String[] args) {
           Pattern pattern = Pattern.compile("^(?!.*<[^>]+>).*");
           Matcher matcher = pattern.matcher("This is \n \n");
           boolean matched = matcher.matches();
           if(matched) {
               System.out.println("Match found");
           } else {
               System.out.println("Match not found");
           }
       }
   }