BinarySearchTest.java

packagecom.thealgorithms.searches;

importstaticorg.junit.jupiter.api.Assertions.assertEquals;

importjava.util.stream.IntStream;
importorg.junit.jupiter.api.Test;

/**
 * Unit tests for the BinarySearch class.
 */
classBinarySearchTest {

/**
 * Test for basic binary search functionality.
 */
@Test
voidtestBinarySearchFound() {
BinarySearchbinarySearch = newBinarySearch();
Integer[] array = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
intkey = 7;
intexpectedIndex = 6; // Index of the key in the array
assertEquals(expectedIndex, binarySearch.find(array, key), "The index of the found element should be 6.");
 }

/**
 * Test for binary search when the element is not present.
 */
@Test
voidtestBinarySearchNotFound() {
BinarySearchbinarySearch = newBinarySearch();
Integer[] array = {1, 2, 3, 4, 5};
intkey = 6; // Element not present in the array
intexpectedIndex = -1; // Key not found
assertEquals(expectedIndex, binarySearch.find(array, key), "The element should not be found in the array.");
 }

/**
 * Test for binary search with first element as the key.
 */
@Test
voidtestBinarySearchFirstElement() {
BinarySearchbinarySearch = newBinarySearch();
Integer[] array = {1, 2, 3, 4, 5};
intkey = 1; // First element
intexpectedIndex = 0; // Index of the key in the array
assertEquals(expectedIndex, binarySearch.find(array, key), "The index of the first element should be 0.");
 }

/**
 * Test for binary search with last element as the key.
 */
@Test
voidtestBinarySearchLastElement() {
BinarySearchbinarySearch = newBinarySearch();
Integer[] array = {1, 2, 3, 4, 5};
intkey = 5; // Last element
intexpectedIndex = 4; // Index of the key in the array
assertEquals(expectedIndex, binarySearch.find(array, key), "The index of the last element should be 4.");
 }

/**
 * Test for binary search with a single element present.
 */
@Test
voidtestBinarySearchSingleElementFound() {
BinarySearchbinarySearch = newBinarySearch();
Integer[] array = {1};
intkey = 1; // Only element present
intexpectedIndex = 0; // Index of the key in the array
assertEquals(expectedIndex, binarySearch.find(array, key), "The index of the single element should be 0.");
 }

/**
 * Test for binary search with a single element not present.
 */
@Test
voidtestBinarySearchSingleElementNotFound() {
BinarySearchbinarySearch = newBinarySearch();
Integer[] array = {1};
intkey = 2; // Key not present
intexpectedIndex = -1; // Key not found
assertEquals(expectedIndex, binarySearch.find(array, key), "The element should not be found in the array.");
 }

/**
 * Test for binary search with an empty array.
 */
@Test
voidtestBinarySearchEmptyArray() {
BinarySearchbinarySearch = newBinarySearch();
Integer[] array = {}; // Empty array
intkey = 1; // Key not present
intexpectedIndex = -1; // Key not found
assertEquals(expectedIndex, binarySearch.find(array, key), "The element should not be found in an empty array.");
 }

/**
 * Test for binary search on large array.
 */
@Test
voidtestBinarySearchLargeArray() {
BinarySearchbinarySearch = newBinarySearch();
Integer[] array = IntStream.range(0, 10000).boxed().toArray(Integer[] ::new); // Array from 0 to 9999
intkey = 9999; // Last element
intexpectedIndex = 9999; // Index of the last element
assertEquals(expectedIndex, binarySearch.find(array, key), "The index of the last element should be 9999.");
 }
}