Add Longest Subarray With Sum Less Than or Equal to K algorithm (#6042)

src/test/java/com/thealgorithms/slidingwindow/LongestSubarrayWithSumLessOrEqualToKTest.java

@@ -0,0 +1,22 @@
+package com.thealgorithms.slidingwindow;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for the LongestSubarrayWithSumLessOrEqualToK algorithm.
+ */
+public class LongestSubarrayWithSumLessOrEqualToKTest {
+
+    /**
+     * Tests for the longest subarray with a sum less than or equal to k.
+     */
+    @Test
+    public void testLongestSubarrayWithSumLEK() {
+        assertEquals(3, LongestSubarrayWithSumLessOrEqualToK.longestSubarrayWithSumLEK(new int[] {1, 2, 3, 4}, 6)); // {1, 2, 3}
+        assertEquals(4, LongestSubarrayWithSumLessOrEqualToK.longestSubarrayWithSumLEK(new int[] {1, 2, 3, 4}, 10)); // {1, 2, 3, 4}
+        assertEquals(2, LongestSubarrayWithSumLessOrEqualToK.longestSubarrayWithSumLEK(new int[] {5, 1, 2, 3}, 5)); // {5}
+        assertEquals(0, LongestSubarrayWithSumLessOrEqualToK.longestSubarrayWithSumLEK(new int[] {1, 2, 3}, 0)); // No valid subarray
+    }
+}