Add tests, improve docs in NewManShanksPrime (#5660)

src/main/java/com/thealgorithms/dynamicprogramming/NewManShanksPrime.java

@@ -1,25 +1,48 @@
 package com.thealgorithms.dynamicprogramming;
 
 /**
+ * The NewManShanksPrime class provides a method to determine whether the nth
+ * New Man Shanks prime matches an expected answer.
+ *
+ * <p>This is based on the New Man Shanks prime sequence defined by the recurrence
+ * relation:</p>
+ *
+ * <pre>
+ * a(n) = 2 * a(n-1) + a(n-2) for n >= 2
+ * a(0) = 1
+ * a(1) = 1
+ * </pre>
+ *
+ * <p>For more information on New Man Shanks primes, please refer to the
+ * <a href="https://en.wikipedia.org/wiki/Newman%E2%80%93Shanks%E2%80%93Williams_prime">
+ * Wikipedia article</a>.</p>
+ *
+ * <p>Note: The class is designed to be non-instantiable.</p>
+ *
  * @author <a href="https://github.com/siddhant2002">Siddhant Swarup Mallick</a>
- * Program description - To find the New Man Shanks Prime.
- * <a href="https://en.wikipedia.org/wiki/Newman%E2%80%93Shanks%E2%80%93Williams_prime">Wikipedia</a>
  */
 public final class NewManShanksPrime {
     private NewManShanksPrime() {
     }
 
+    /**
+     * Calculates the nth New Man Shanks prime and checks if it equals the
+     * expected answer.
+     *
+     * @param n the index of the New Man Shanks prime to calculate (0-based).
+     * @param expectedAnswer the expected value of the nth New Man Shanks prime.
+     * @return true if the calculated nth New Man Shanks prime matches the
+     *         expected answer; false otherwise.
+     */
     public static boolean nthManShanksPrime(int n, int expectedAnswer) {
         int[] a = new int[n + 1];
-        // array of n+1 size is initialized
         a[0] = 1;
         a[1] = 1;
-        // The 0th and 1st index position values are fixed. They are initialized as 1
+
         for (int i = 2; i <= n; i++) {
             a[i] = 2 * a[i - 1] + a[i - 2];
         }
-        // The loop is continued till n
+
         return a[n] == expectedAnswer;
-        // returns true if calculated answer matches with expected answer
     }
 }

src/test/java/com/thealgorithms/dynamicprogramming/NewManShanksPrimeTest.java

@@ -0,0 +1,80 @@
+package com.thealgorithms.dynamicprogramming;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for the NewManShanksPrime class.
+ * This test class verifies the correctness of the nthManShanksPrime method
+ * for various input cases.
+ */
+class NewManShanksPrimeTest {
+
+    /**
+     * Test case for the 1st New Man Shanks prime.
+     * The expected answer is 1.
+     */
+    @Test
+    void testNthManShanksPrime1() {
+        int n = 1;
+        int expectedAnswer = 1;
+        assertTrue(NewManShanksPrime.nthManShanksPrime(n, expectedAnswer), "The 1st New Man Shanks prime should be 1.");
+    }
+
+    /**
+     * Test case for the 2nd New Man Shanks prime.
+     * The expected answer is 3.
+     */
+    @Test
+    void testNthManShanksPrime2() {
+        int n = 2;
+        int expectedAnswer = 3;
+        assertTrue(NewManShanksPrime.nthManShanksPrime(n, expectedAnswer), "The 2nd New Man Shanks prime should be 3.");
+    }
+
+    /**
+     * Test case for the 3rd New Man Shanks prime.
+     * The expected answer is 7.
+     */
+    @Test
+    void testNthManShanksPrime3() {
+        int n = 3;
+        int expectedAnswer = 7;
+        assertTrue(NewManShanksPrime.nthManShanksPrime(n, expectedAnswer), "The 3rd New Man Shanks prime should be 7.");
+    }
+
+    /**
+     * Test case for the 4th New Man Shanks prime.
+     * The expected answer is 17.
+     */
+    @Test
+    void testNthManShanksPrime4() {
+        int n = 4;
+        int expectedAnswer = 17;
+        assertTrue(NewManShanksPrime.nthManShanksPrime(n, expectedAnswer), "The 4th New Man Shanks prime should be 17.");
+    }
+
+    /**
+     * Test case for the 5th New Man Shanks prime.
+     * The expected answer is 41.
+     */
+    @Test
+    void testNthManShanksPrime5() {
+        int n = 5;
+        int expectedAnswer = 41;
+        assertTrue(NewManShanksPrime.nthManShanksPrime(n, expectedAnswer), "The 5th New Man Shanks prime should be 41.");
+    }
+
+    /**
+     * Test case with an incorrect expected answer.
+     * For n = 2, the expected answer is 3.
+     */
+    @Test
+    void testNthManShanksPrimeIncorrectAnswer() {
+        int n = 2;
+        int expectedAnswer = 4; // Incorrect expected value
+        assertFalse(NewManShanksPrime.nthManShanksPrime(n, expectedAnswer), "The 2nd New Man Shanks prime should not be 4.");
+    }
+}