test: LongestAlternatingSubsequenceTest (#5399)

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

@@ -0,0 +1,22 @@
+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 LongestAlternatingSubsequenceTest {
+
+    @ParameterizedTest
+    @MethodSource("provideTestCases")
+    void testAlternatingLength(int[] arr, int expected) {
+        assertEquals(expected, LongestAlternatingSubsequence.alternatingLength(arr, arr.length));
+    }
+
+    private static Stream<Arguments> provideTestCases() {
+        return Stream.of(Arguments.of(new int[] {1}, 1), Arguments.of(new int[] {1, 2}, 2), Arguments.of(new int[] {2, 1}, 2), Arguments.of(new int[] {1, 3, 2, 4, 3, 5}, 6), Arguments.of(new int[] {1, 2, 3, 4, 5}, 2), Arguments.of(new int[] {5, 4, 3, 2, 1}, 2),
+            Arguments.of(new int[] {10, 22, 9, 33, 49, 50, 31, 60}, 6), Arguments.of(new int[] {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, 2));
+    }
+}