diff --git a/core-java-modules/core-java-regex/src/test/java/com/baeldung/replaceall/ReplaceAllWithWhitespaceRegexUnitTest.java b/core-java-modules/core-java-regex/src/test/java/com/baeldung/replaceall/ReplaceAllWithWhitespaceRegexUnitTest.java
new file mode 100644
index 0000000000..a95d1afd80
--- /dev/null
+++ b/core-java-modules/core-java-regex/src/test/java/com/baeldung/replaceall/ReplaceAllWithWhitespaceRegexUnitTest.java
@@ -0,0 +1,32 @@
+package com.baeldung.replaceall;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class ReplaceAllWithWhitespaceRegexUnitTest {
+    private static final String INPUT_STR = "Text   With     Whitespaces!   ";
+
+    @Test
+    public void givenString_whenReplaceBySingleCharClass_thenGetExpect() {
+        String expected = "Text___With_____Whitespaces!___";
+        String result = INPUT_STR.replaceAll("\\s", "_");
+        assertEquals(expected, result);
+    }
+
+    @Test
+    public void givenString_whenReplaceBySingleCharClassWithPlus_thenGetExpect() {
+        String expected = "Text_With_Whitespaces!_";
+        String result = INPUT_STR.replaceAll("\\s+", "_");
+        assertEquals(expected, result);
+    }
+
+    @Test
+    public void givenString_whenRemoveByWhitespace_thenGetSameResult() {
+        String expected = "TextWithWhitespaces!";
+        String result1 = INPUT_STR.replaceAll("\\s", "");
+        String result2 = INPUT_STR.replaceAll("\\s+", "");
+        assertEquals(expected, result1);
+        assertEquals(result1, result2);
+    }
+}