Add tests, remove main, improve docs in ExponentialSearch (#5664)

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

@@ -0,0 +1,84 @@
+package com.thealgorithms.searches;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.stream.IntStream;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for the ExponentialSearch class.
+ */
+class ExponentialSearchTest {
+
+    /**
+     * Test for basic exponential search functionality.
+     */
+    @Test
+    void testExponentialSearchFound() {
+        ExponentialSearch exponentialSearch = new ExponentialSearch();
+        Integer[] array = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
+        int key = 7;
+        int expectedIndex = 6; // Index of the key in the array
+        assertEquals(expectedIndex, exponentialSearch.find(array, key), "The index of the found element should be 6.");
+    }
+
+    /**
+     * Test for exponential search with the first element as the key.
+     */
+    @Test
+    void testExponentialSearchFirstElement() {
+        ExponentialSearch exponentialSearch = new ExponentialSearch();
+        Integer[] array = {1, 2, 3, 4, 5};
+        int key = 1; // First element
+        int expectedIndex = 0; // Index of the key in the array
+        assertEquals(expectedIndex, exponentialSearch.find(array, key), "The index of the first element should be 0.");
+    }
+
+    /**
+     * Test for exponential search with the last element as the key.
+     */
+    @Test
+    void testExponentialSearchLastElement() {
+        ExponentialSearch exponentialSearch = new ExponentialSearch();
+        Integer[] array = {1, 2, 3, 4, 5};
+        int key = 5; // Last element
+        int expectedIndex = 4; // Index of the key in the array
+        assertEquals(expectedIndex, exponentialSearch.find(array, key), "The index of the last element should be 4.");
+    }
+
+    /**
+     * Test for exponential search with a single element present.
+     */
+    @Test
+    void testExponentialSearchSingleElementFound() {
+        ExponentialSearch exponentialSearch = new ExponentialSearch();
+        Integer[] array = {1};
+        int key = 1; // Only element present
+        int expectedIndex = 0; // Index of the key in the array
+        assertEquals(expectedIndex, exponentialSearch.find(array, key), "The index of the single element should be 0.");
+    }
+
+    /**
+     * Test for exponential search with an empty array.
+     */
+    @Test
+    void testExponentialSearchEmptyArray() {
+        ExponentialSearch exponentialSearch = new ExponentialSearch();
+        Integer[] array = {}; // Empty array
+        int key = 1; // Key not present
+        int expectedIndex = -1; // Key not found
+        assertEquals(expectedIndex, exponentialSearch.find(array, key), "The element should not be found in an empty array.");
+    }
+
+    /**
+     * Test for exponential search on large array.
+     */
+    @Test
+    void testExponentialSearchLargeArray() {
+        ExponentialSearch exponentialSearch = new ExponentialSearch();
+        Integer[] array = IntStream.range(0, 10000).boxed().toArray(Integer[] ::new); // Array from 0 to 9999
+        int key = 9999;
+        int expectedIndex = 9999;
+        assertEquals(expectedIndex, exponentialSearch.find(array, key), "The index of the last element should be 9999.");
+    }
+}