Add tests, remove main in LowerBound (#5672)

Author: Hardvan

DIRECTORY.md

@@ -1036,6 +1036,7 @@
             * [KMPSearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/KMPSearchTest.java)
             * [LinearSearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/LinearSearchTest.java)
             * [LinearSearchThreadTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/LinearSearchThreadTest.java)
+            * [LowerBoundTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/LowerBoundTest.java)
             * [MonteCarloTreeSearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/MonteCarloTreeSearchTest.java)
             * [OrderAgnosticBinarySearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/OrderAgnosticBinarySearchTest.java)
             * [PerfectBinarySearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/PerfectBinarySearchTest.java)

src/main/java/com/thealgorithms/searches/LowerBound.java

@@ -1,9 +1,6 @@
 package com.thealgorithms.searches;
 
 import com.thealgorithms.devutils.searches.SearchAlgorithm;
-import java.util.Random;
-import java.util.concurrent.ThreadLocalRandom;
-import java.util.stream.IntStream;
 
 /**
  * The LowerBound method is used to return an index pointing to the first
@@ -25,28 +22,6 @@
  */
 class LowerBound implements SearchAlgorithm {
 
-    // Driver Program
-    public static void main(String[] args) {
-        // Just generate data
-        Random r = ThreadLocalRandom.current();
-
-        int size = 100;
-        int maxElement = 100000;
-
-        Integer[] integers = IntStream.generate(() -> r.nextInt(maxElement)).limit(size).sorted().boxed().toArray(Integer[] ::new);
-
-        // The element for which the lower bound is to be found
-        int val = integers[r.nextInt(size - 1)] + 1;
-
-        LowerBound search = new LowerBound();
-        int atIndex = search.find(integers, val);
-
-        System.out.printf("Val: %d. Lower Bound Found %d at index %d. An array length %d%n", val, integers[atIndex], atIndex, size);
-
-        boolean toCheck = integers[atIndex] >= val || integers[size - 1] < val;
-        System.out.printf("Lower Bound found at an index: %d. Is greater or max element: %b%n", atIndex, toCheck);
-    }
-
     /**
      * @param array is an array where the LowerBound value is to be found
      * @param key is an element for which the LowerBound is to be found

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

@@ -0,0 +1,59 @@
+package com.thealgorithms.searches;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+class LowerBoundTest {
+
+    /**
+     * Test finding the lower bound for an element present in the array.
+     */
+    @Test
+    void testLowerBoundElementPresent() {
+        Integer[] array = {1, 2, 3, 4, 5};
+        LowerBound lowerBound = new LowerBound();
+
+        // Test for a value that is present
+        assertEquals(2, lowerBound.find(array, 3), "Lower bound for 3 should be at index 2");
+        assertEquals(0, lowerBound.find(array, 1), "Lower bound for 1 should be at index 0");
+        assertEquals(4, lowerBound.find(array, 5), "Lower bound for 5 should be at index 4");
+    }
+
+    /**
+     * Test finding the lower bound for a value greater than the maximum element in the array.
+     */
+    @Test
+    void testLowerBoundElementGreaterThanMax() {
+        Integer[] array = {1, 2, 3, 4, 5};
+        LowerBound lowerBound = new LowerBound();
+
+        // Test for a value greater than the maximum
+        assertEquals(4, lowerBound.find(array, 6), "Lower bound for 6 should be at index 4");
+    }
+
+    /**
+     * Test finding the lower bound for a value less than the minimum element in the array.
+     */
+    @Test
+    void testLowerBoundElementLessThanMin() {
+        Integer[] array = {1, 2, 3, 4, 5};
+        LowerBound lowerBound = new LowerBound();
+
+        // Test for a value less than the minimum
+        assertEquals(0, lowerBound.find(array, 0), "Lower bound for 0 should be at index 0");
+    }
+
+    /**
+     * Test finding the lower bound for a non-existent value that falls between two elements.
+     */
+    @Test
+    void testLowerBoundNonExistentValue() {
+        Integer[] array = {1, 2, 3, 4, 5};
+        LowerBound lowerBound = new LowerBound();
+
+        // Test for a value that is not present
+        assertEquals(4, lowerBound.find(array, 7), "Lower bound for 7 should be at index 4");
+        assertEquals(0, lowerBound.find(array, 0), "Lower bound for 0 should be at index 0");
+    }
+}