test: add unit tests for NaivePatternSearch

This commit adds JUnit 5 test cases for the NaivePatternSearch algorithm.

- Verifies correct detection of multiple matches in a string
- Covers cases where the pattern is not found
- Tests matching at the end of the text
- Tests when the text and pattern are equal

These tests ensure correctness and improve reliability of the algorithm.

Author: Karthikn-VR

src/test/java/com/thealgorithms/strings/NaivePatternSearchTest.java

@@ -0,0 +1,41 @@
+package strings;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+class NaivePatternSearchTest {
+
+    @Test
+    void testPatternFound() {
+        String text = "abcdxabchjikabc";
+        String pattern = "abc";
+        List<Integer> result = NaivePatternSearch.search(text, pattern);
+        assertEquals(List.of(0, 5, 12), result);
+    }
+
+    @Test
+    void testPatternNotFound() {
+        String text = "hello world";
+        String pattern = "abc";
+        List<Integer> result = NaivePatternSearch.search(text, pattern);
+        assertTrue(result.isEmpty());
+    }
+
+    @Test
+    void testPatternAtEnd() {
+        String text = "xyzabc";
+        String pattern = "abc";
+        List<Integer> result = NaivePatternSearch.search(text, pattern);
+        assertEquals(List.of(3), result);
+    }
+
+    @Test
+    void testPatternEqualsText() {
+        String text = "abc";
+        String pattern = "abc";
+        List<Integer> result = NaivePatternSearch.search(text, pattern);
+        assertEquals(List.of(0), result);
+    }
+}