Add tests, remove main in PalindromePrime (#5773)

src/test/java/com/thealgorithms/misc/PalindromePrimeTest.java

@@ -0,0 +1,53 @@
+package com.thealgorithms.misc;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+public class PalindromePrimeTest {
+
+    @Test
+    public void testPrimeWithPrimeNumbers() {
+        assertTrue(PalindromePrime.prime(2), "2 should be prime");
+        assertTrue(PalindromePrime.prime(3), "3 should be prime");
+        assertTrue(PalindromePrime.prime(5), "5 should be prime");
+        assertTrue(PalindromePrime.prime(11), "11 should be prime");
+    }
+
+    @Test
+    public void testPrimeWithNonPrimeNumbers() {
+        assertFalse(PalindromePrime.prime(1), "1 is not prime");
+        assertFalse(PalindromePrime.prime(4), "4 is not prime");
+        assertFalse(PalindromePrime.prime(9), "9 is not prime");
+        assertFalse(PalindromePrime.prime(15), "15 is not prime");
+    }
+
+    @Test
+    public void testReverse() {
+        assertEquals(123, PalindromePrime.reverse(321), "Reverse of 321 should be 123");
+        assertEquals(7, PalindromePrime.reverse(7), "Reverse of 7 should be 7");
+        assertEquals(1221, PalindromePrime.reverse(1221), "Reverse of 1221 should be 1221");
+    }
+
+    @Test
+    public void testGeneratePalindromePrimes() {
+        List<Integer> result = PalindromePrime.generatePalindromePrimes(5);
+        List<Integer> expected = List.of(2, 3, 5, 7, 11);
+        assertEquals(expected, result, "The first 5 palindromic primes should be [2, 3, 5, 7, 11]");
+    }
+
+    @Test
+    public void testGeneratePalindromePrimesWithZero() {
+        List<Integer> result = PalindromePrime.generatePalindromePrimes(0);
+        assertTrue(result.isEmpty(), "Generating 0 palindromic primes should return an empty list");
+    }
+
+    @Test
+    public void testGeneratePalindromePrimesWithNegativeInput() {
+        List<Integer> result = PalindromePrime.generatePalindromePrimes(-5);
+        assertTrue(result.isEmpty(), "Generating a negative number of palindromic primes should return an empty list");
+    }
+}