diff --git a/core-java/src/test/java/com/baeldung/string/CharSequenceVsStringUnitTest.java b/core-java/src/test/java/com/baeldung/string/CharSequenceVsStringUnitTest.java
new file mode 100644
index 0000000000..1378b5d876
--- /dev/null
+++ b/core-java/src/test/java/com/baeldung/string/CharSequenceVsStringUnitTest.java
@@ -0,0 +1,47 @@
+package com.baeldung.string;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertTrue;
+
+public class CharSequenceVsStringUnitTest {
+
+    @Test
+    public void givenUsingString_whenInstantiatingString_thenWrong() {
+        CharSequence firstString = "bealdung";
+        String secondString = "baeldung";
+
+        assertNotEquals(firstString, secondString);
+    }
+
+    @Test
+    public void givenIdenticalCharSequences_whenCastToString_thenEqual() {
+        CharSequence charSequence1 = "baeldung_1";
+        CharSequence charSequence2 = "baeldung_2";
+
+        assertTrue(charSequence1.toString().compareTo(charSequence2.toString()) > 0);
+    }
+
+    @Test
+    public void givenString_whenAppended_thenUnmodified() {
+        String test = "a";
+        int firstAddressOfTest = System.identityHashCode(test);
+        test += "b";
+        int secondAddressOfTest = System.identityHashCode(test);
+
+        assertEquals(firstAddressOfTest, secondAddressOfTest);
+    }
+
+    @Test
+    public void givenStringBuilder_whenAppended_thenModified() {
+        StringBuilder test = new StringBuilder();
+        test.append("a");
+        int firstAddressOfTest = System.identityHashCode(test);
+        test.append("b");
+        int secondAddressOfTest = System.identityHashCode(test);
+
+        assertEquals(firstAddressOfTest, secondAddressOfTest);
+    }
+}