This commit is related to BAEL-7024 (#15564)

This commit aims to add a new test class "ReplaceNonPrintableCharsUnitTest".

core-java-modules/core-java-string-operations-7/src/test/java/com/baeldung/replacenonprintablecharacters/ReplaceNonPrintableCharsUnitTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.replacenonprintablecharacters;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class ReplaceNonPrintableCharsUnitTest {
+    @Test
+    public void givenTextWithNonPrintableChars_whenUsingRegularExpression_thenGetSanitizedText() {
+        String originalText = "\n\nWelcome \n\n\n\tto Baeldung!\n\t";
+        String expected = "Welcome to Baeldung!";
+        String regex = "[\\p{C}]";
+
+        Pattern pattern = Pattern.compile(regex);
+        Matcher matcher = pattern.matcher(originalText);
+        String sanitizedText = matcher.replaceAll("");
+
+        assertEquals(expected, sanitizedText);
+    }
+
+    @Test
+    public void givenTextWithNonPrintableChars_whenCustomImplementation_thenGetSanitizedText() {
+        String originalText = "\n\nWelcome \n\n\n\tto Baeldung!\n\t";
+        String expected = "Welcome to Baeldung!";
+
+        StringBuilder strBuilder = new StringBuilder();
+        originalText.codePoints().forEach((i) -> {
+            if (i >= 32 && i != 127) {
+                strBuilder.append(Character.toChars(i));
+            }
+        });
+
+        assertEquals(expected, strBuilder.toString());
+    }
+
+}