Testing the private constructor

Author: miladsade96

src/test/java/com/thealgorithms/strings/AlternativeStringArrangeTest.java

@@ -1,5 +1,6 @@
 package com.thealgorithms.strings;
 
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.MethodSource;
 
@@ -29,4 +30,17 @@ private static Stream<Object[]> provideTestData() {
     void arrangeTest(String input1, String input2, String expected) {
         assertEquals(expected, AlternativeStringArrange.arrange(input1, input2));
     }
+
+    // Testing private constructor to prevent instantiation
+    @Test
+    void preventInstantiationTest() {
+        try {
+            var constructor = AlternativeStringArrange.class.getDeclaredConstructor();
+            constructor.setAccessible(true);
+            constructor.newInstance();
+        } catch (Exception e) {
+            assertEquals(IllegalStateException.class, e.getCause().getClass());
+            assertEquals("Utility class", e.getCause().getMessage());
+        }
+    }
 }