Add tests, remove main in UpperBound (#5679)

src/test/java/com/thealgorithms/searches/UpperBoundTest.java

@@ -0,0 +1,99 @@
+package com.thealgorithms.searches;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Random;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class UpperBoundTest {
+
+    private UpperBound upperBound;
+    private Integer[] sortedArray;
+
+    @BeforeEach
+    void setUp() {
+        upperBound = new UpperBound();
+
+        // Generate a sorted array of random integers for testing
+        Random random = new Random();
+        int size = 100;
+        int maxElement = 100;
+        sortedArray = random.ints(size, 1, maxElement)
+                          .distinct() // Ensure all elements are unique
+                          .sorted()
+                          .boxed()
+                          .toArray(Integer[] ::new);
+    }
+
+    @Test
+    void testUpperBoundFound() {
+        int key = sortedArray[sortedArray.length - 1] + 1; // Test with a key larger than max element
+        int index = upperBound.find(sortedArray, key);
+
+        // The upper bound should be equal to the length of the array
+        assertEquals(sortedArray.length - 1, index, "Upper bound for a larger key should be the size of the array.");
+    }
+
+    @Test
+    void testUpperBoundExactMatch() {
+        int key = sortedArray[sortedArray.length / 2]; // Choose a key from the middle of the array
+        int index = upperBound.find(sortedArray, key);
+
+        // The index should point to the first element greater than the key
+        assertTrue(index < sortedArray.length, "Upper bound should not exceed array length.");
+        assertTrue(sortedArray[index] > key, "The element at the index should be greater than the key.");
+    }
+
+    @Test
+    void testUpperBoundMultipleValues() {
+        Integer[] arrayWithDuplicates = new Integer[] {1, 1, 2, 3, 4, 4, 5, 6, 7, 8, 9}; // Test array with duplicates
+        int key = 4;
+        int index = upperBound.find(arrayWithDuplicates, key);
+
+        assertTrue(index < arrayWithDuplicates.length, "Upper bound index should be valid.");
+        assertEquals(6, index, "The upper bound for 4 should be the index of the first 5.");
+        assertTrue(arrayWithDuplicates[index] > key, "Element at the upper bound index should be greater than the key.");
+    }
+
+    @Test
+    void testUpperBoundLowerThanMin() {
+        int key = 0; // Test with a key lower than the minimum element
+        int index = upperBound.find(sortedArray, key);
+
+        assertEquals(0, index, "Upper bound for a key lower than minimum should be 0.");
+        assertTrue(sortedArray[index] > key, "The element at index 0 should be greater than the key.");
+    }
+
+    @Test
+    void testUpperBoundHigherThanMax() {
+        int key = sortedArray[sortedArray.length - 1] + 1; // Test with a key higher than maximum element
+        int index = upperBound.find(sortedArray, key);
+
+        assertEquals(sortedArray.length - 1, index, "Upper bound for a key higher than maximum should be the size of the array.");
+    }
+
+    @Test
+    void testUpperBoundEdgeCase() {
+        // Edge case: empty array
+        Integer[] emptyArray = {};
+        int index = upperBound.find(emptyArray, 5);
+
+        assertEquals(0, index, "Upper bound for an empty array should be 0.");
+    }
+
+    @Test
+    void testUpperBoundSingleElementArray() {
+        Integer[] singleElementArray = {10};
+        int index = upperBound.find(singleElementArray, 5);
+
+        assertEquals(0, index, "Upper bound for 5 in a single element array should be 0.");
+
+        index = upperBound.find(singleElementArray, 10);
+        assertEquals(0, index, "Upper bound for 10 in a single element array should be 0.");
+
+        index = upperBound.find(singleElementArray, 15);
+        assertEquals(0, index, "Upper bound for 15 in a single element array should be 0.");
+    }
+}