refactor: Enhance docs, code, add tests in LeonardoNumber (#6743)

src/test/java/com/thealgorithms/maths/LeonardoNumberTest.java

@@ -1,29 +1,171 @@
 package com.thealgorithms.maths;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
-public class LeonardoNumberTest {
+/**
+ * Test cases for {@link LeonardoNumber} class.
+ * <p>
+ * Tests both recursive and iterative implementations with various input values
+ * including edge cases and boundary conditions.
+ */
+class LeonardoNumberTest {
+
+    // Tests for recursive implementation
+
     @Test
-    void leonardoNumberNegative() {
-        assertThrows(ArithmeticException.class, () -> LeonardoNumber.leonardoNumber(-1));
+    void testLeonardoNumberNegative() {
+        Assertions.assertThrows(IllegalArgumentException.class, () -> LeonardoNumber.leonardoNumber(-1));
     }
+
     @Test
-    void leonardoNumberZero() {
-        assertEquals(1, LeonardoNumber.leonardoNumber(0));
+    void testLeonardoNumberNegativeLarge() {
+        Assertions.assertThrows(IllegalArgumentException.class, () -> LeonardoNumber.leonardoNumber(-100));
     }
+
     @Test
-    void leonardoNumberOne() {
-        assertEquals(1, LeonardoNumber.leonardoNumber(1));
+    void testLeonardoNumberZero() {
+        Assertions.assertEquals(1, LeonardoNumber.leonardoNumber(0));
     }
+
     @Test
-    void leonardoNumberFive() {
-        assertEquals(15, LeonardoNumber.leonardoNumber(5));
+    void testLeonardoNumberOne() {
+        Assertions.assertEquals(1, LeonardoNumber.leonardoNumber(1));
     }
+
     @Test
-    void leonardoNumberTwenty() {
-        assertEquals(21891, LeonardoNumber.leonardoNumber(20));
+    void testLeonardoNumberTwo() {
+        Assertions.assertEquals(3, LeonardoNumber.leonardoNumber(2));
+    }
+
+    @Test
+    void testLeonardoNumberThree() {
+        Assertions.assertEquals(5, LeonardoNumber.leonardoNumber(3));
+    }
+
+    @Test
+    void testLeonardoNumberFour() {
+        Assertions.assertEquals(9, LeonardoNumber.leonardoNumber(4));
+    }
+
+    @Test
+    void testLeonardoNumberFive() {
+        Assertions.assertEquals(15, LeonardoNumber.leonardoNumber(5));
+    }
+
+    @Test
+    void testLeonardoNumberSix() {
+        Assertions.assertEquals(25, LeonardoNumber.leonardoNumber(6));
+    }
+
+    @Test
+    void testLeonardoNumberSeven() {
+        Assertions.assertEquals(41, LeonardoNumber.leonardoNumber(7));
+    }
+
+    @Test
+    void testLeonardoNumberEight() {
+        Assertions.assertEquals(67, LeonardoNumber.leonardoNumber(8));
+    }
+
+    @Test
+    void testLeonardoNumberTen() {
+        Assertions.assertEquals(177, LeonardoNumber.leonardoNumber(10));
+    }
+
+    @Test
+    void testLeonardoNumberFifteen() {
+        Assertions.assertEquals(1973, LeonardoNumber.leonardoNumber(15));
+    }
+
+    @Test
+    void testLeonardoNumberTwenty() {
+        Assertions.assertEquals(21891, LeonardoNumber.leonardoNumber(20));
+    }
+
+    // Tests for iterative implementation
+
+    @Test
+    void testLeonardoNumberIterativeNegative() {
+        Assertions.assertThrows(IllegalArgumentException.class, () -> LeonardoNumber.leonardoNumberIterative(-1));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeNegativeLarge() {
+        Assertions.assertThrows(IllegalArgumentException.class, () -> LeonardoNumber.leonardoNumberIterative(-50));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeZero() {
+        Assertions.assertEquals(1, LeonardoNumber.leonardoNumberIterative(0));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeOne() {
+        Assertions.assertEquals(1, LeonardoNumber.leonardoNumberIterative(1));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeTwo() {
+        Assertions.assertEquals(3, LeonardoNumber.leonardoNumberIterative(2));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeThree() {
+        Assertions.assertEquals(5, LeonardoNumber.leonardoNumberIterative(3));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeFour() {
+        Assertions.assertEquals(9, LeonardoNumber.leonardoNumberIterative(4));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeFive() {
+        Assertions.assertEquals(15, LeonardoNumber.leonardoNumberIterative(5));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeSix() {
+        Assertions.assertEquals(25, LeonardoNumber.leonardoNumberIterative(6));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeSeven() {
+        Assertions.assertEquals(41, LeonardoNumber.leonardoNumberIterative(7));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeEight() {
+        Assertions.assertEquals(67, LeonardoNumber.leonardoNumberIterative(8));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeTen() {
+        Assertions.assertEquals(177, LeonardoNumber.leonardoNumberIterative(10));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeFifteen() {
+        Assertions.assertEquals(1973, LeonardoNumber.leonardoNumberIterative(15));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeTwenty() {
+        Assertions.assertEquals(21891, LeonardoNumber.leonardoNumberIterative(20));
+    }
+
+    @Test
+    void testLeonardoNumberIterativeTwentyFive() {
+        Assertions.assertEquals(242785, LeonardoNumber.leonardoNumberIterative(25));
+    }
+
+    // Consistency tests between recursive and iterative implementations
+
+    @Test
+    void testConsistencyBetweenImplementations() {
+        for (int i = 0; i <= 15; i++) {
+            Assertions.assertEquals(LeonardoNumber.leonardoNumber(i), LeonardoNumber.leonardoNumberIterative(i), "Mismatch at index " + i);
+        }
     }
 }