| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.numbers.combinatorics; |
| |
| import org.junit.jupiter.api.Assertions; |
| import org.junit.jupiter.api.Test; |
| |
| /** |
| * Test cases for the {@link Factorial} class. |
| */ |
| public class FactorialTest { |
| @Test |
| void testFactorialZero() { |
| Assertions.assertEquals(1, Factorial.value(0), "0!"); |
| } |
| |
| @Test |
| void testFactorial() { |
| for (int i = 1; i < 21; i++) { |
| Assertions.assertEquals(factorial(i), Factorial.value(i), i + "!"); |
| } |
| } |
| |
| @Test |
| void testPrecondition1() { |
| Assertions.assertThrows(IllegalArgumentException.class, |
| () -> Factorial.value(-1) |
| ); |
| } |
| |
| @Test |
| void testPrecondition2() { |
| Assertions.assertThrows(IllegalArgumentException.class, |
| () -> Factorial.value(21) |
| ); |
| } |
| |
| /** |
| * Direct multiplication implementation. |
| */ |
| private long factorial(int n) { |
| long result = 1; |
| for (int i = 2; i <= n; i++) { |
| result *= i; |
| } |
| return result; |
| } |
| } |