BAEL-9063 (#18301)

* BAEL-9063

* BAEL-9063

---------

Co-authored-by: Neetika Khandelwal <[email protected]>

Author: Neetika23

core-java-modules/core-java-string-operations-12/src/test/java/com/baeldung/substringoperations/StringSlicingUnitTest.java

@@ -0,0 +1,49 @@
+package com.baeldung.substringoperations;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class StringSlicingUnitTest {
+
+    @Test
+    void givenString_whenExtract_thenOutputSubstring() {
+        String s = "Hello, World!";
+        assertEquals("Hello", s.substring(0, 5));
+        assertEquals("World!", s.substring(7));
+    }
+
+    @Test
+    void givenString_whenNegativeIndexing_thenOutputSubstringEquivalent() {
+        String s = "Hello, World!";
+        assertEquals("World!", s.substring(s.length() - 6));
+    }
+
+    @Test
+    void givenString_whenStepSlicing_thenOutputSubstring() {
+        String s = "Hello, World!";
+        StringBuilder result = new StringBuilder();
+        for (int i = 0; i < s.length(); i += 2) {
+            result.append(s.charAt(i));
+        }
+        assertEquals("Hlo ol!", result.toString());
+    }
+
+    @Test
+    void givenString_whenReverseString_thenOutputString() {
+        String s = "Hello, World!";
+        String reversed = new StringBuilder(s).reverse()
+            .toString();
+        assertEquals("!dlroW ,olleH", reversed);
+    }
+
+    @Test
+    void testNegativeStepWithStartStop() {
+        String s = "Hello, World!";
+        StringBuilder result = new StringBuilder();
+        for (int i = s.length() - 7; i < s.length() - 1; i += 2) {
+            result.append(s.charAt(i));
+        }
+        assertEquals(" ol", result.toString());
+    }
+}