Added Parameterized tests

Author: tejaswi0910

src/test/java/com/thealgorithms/dynamicprogramming/LongestArithmeticSubsequenceTest.java

@@ -0,0 +1,28 @@
+package com.thealgorithms.dynamicprogramming;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.stream.Stream;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+public class LongestArithmeticSubsequenceTest {
+
+    @ParameterizedTest
+    @MethodSource("provideTestCases")
+    void testGetLongestArithmeticSubsequenceLength(int[] nums, int expected) {
+        assertEquals(expected, LongestArithmeticSubsequence.getLongestArithmeticSubsequenceLength(nums));
+    }
+
+    private static Stream<Arguments> provideTestCases() {
+        return Stream.of(
+            Arguments.of(new int[] {3, 6, 9, 12, 15}, 5),
+            Arguments.of(new int[] {1, 7, 10, 13, 14, 19}, 4),
+            Arguments.of(new int[] {1, 2, 3, 4}, 4),
+            Arguments.of(new int[] {}, 0), // Edge case: empty array
+            Arguments.of(new int[] {10}, 1), // Edge case: single element
+            Arguments.of(new int[] {9, 4, 7, 2, 10}, 3) // Random test case
+        );
+    }
+}