我想在junit中编写计算器程序的测试用例。我是junit环境的新手。我可以为其他程序编写测试，但有点像测试switch（）的情况。
我真的想知道如何去做。
提前致谢
这是我的程序
import java.util.Scanner;
//This program performs basic math operations such as :- +,-,*,/
public class Calculator
{
public static void main(String[] args)
{
double number1, number2;
String Mathoperation;
Scanner scannerObject = new Scanner(System.in);
System.out.println("Enter first number");
number1 = scannerObject. nextDouble();
System.out.println("Enter second number");
number2 = scannerObject. nextDouble();
Scanner UserInput = new Scanner(System.in);
System.out.println("\nHere are your options:");
System.out.println("\n1. Addition, 2. Subtraction, 3. Divison, 4. Multiplication");
Mathoperation = UserInput.next();
switch (Mathoperation)
{
case "1":
System.out.println("Your answer is " + (number1 + number2));
break;
case "2":
System.out.println("Your answer is " + (number1 - number2));
break;
case "3":
System.out.println("Your answer is " + (number1 / number2));
break;
case "4":
System.out.println("Your asnwer is " + (number1 * number2));
break;
default:
System.out.println("");
}
}
}
答案 0 :(得分：1)
编写单元测试的第一步是编写可测试的代码。此时您的代码不是非常可测试的，也就是说您可以对其进行测试，但它不会成为最佳测试。让我们来看看为什么。
第一个原因是您的主要功能中包含所有代码。你通常想避免这种情况。这有多种原因，但我认为最大的两个原因是可读性和可重用性。通常你会想把东西放到不同的类中，但是为了时间，我们只需将你的数学开关放到它自己的函数中。
import java.util.Scanner;
//This program performs basic math operations such as :- +,-,*,/
public class Calculator
{
public static void main(String[] args)
{
double number1, number2;
String Mathoperation;
Scanner scannerObject = new Scanner(System.in);
System.out.println("Enter first number");
number1 = scannerObject. nextDouble();
System.out.println("Enter second number");
number2 = scannerObject. nextDouble();
Scanner UserInput = new Scanner(System.in);
System.out.println("\nHere are your options:");
System.out.println("\n1. Addition, 2. Subtraction, 3. Divison, 4. Multiplication");
Mathoperation = UserInput.next();
doMath(Mathoperation, number1, number2)
}
public double doMath(String Mathoperation, double number1, double number2){
switch (Mathoperation)
{
case "1":
System.out.println("Your answer is " + (number1 + number2));
break;
case "2":
System.out.println("Your answer is " + (number1 - number2));
break;
case "3":
System.out.println("Your answer is " + (number1 / number2));
break;
case "4":
System.out.println("Your asnwer is " + (number1 * number2));
break;
default:
System.out.println("");
}
}
}
好的很酷，所以现在我们有自己的方法来进行数学运算。一个问题。这本身并不是一个单元，这实际上是加法和数学运算之间的整合。这意味着，测试时，我们需要测试算术的每个组合（加，子，除，乘）以及方法是否选择正确的算子。那就是我们想要的更多工作，并不是一个非常好的测试，所以我们如何解决这个问题呢？很简单，我们进一步细分
import java.util.Scanner;
//This program performs basic math operations such as :- +,-,*,/
public class Calculator {
//Code for use input somewhere here
public double doMath(String Mathoperation, double number1, double number2){
switch (Mathoperation)
{
case "1":
System.out.println("Your answer is " + add(number1, number2));
break;
case "2":
System.out.println("Your answer is " + sub(number1, number2));
break;
case "3":
System.out.println("Your answer is " + div(number1, number2));
break;
case "4":
System.out.println("Your answer is " + mul(number1, number2));
break;
default:
System.out.println("");
}
}
public double add(double number1, double number2){
return number1 + number2;
}
public double sub(double number1, double number2){
return number1 - number2;
}
public double mul(double number1, double number2){
return number1 * number2;
}
public double div(double number1, double number2){
return number1 / number2;
}
}
现在我们的单位更容易分解。在这里，您可以为add，sub，div和mul函数编写测试。对它们进行测试以确保它们按预期运行。然后编写doMath函数的测试，以确保它将值传递给正确的操作。通过这种方式，当某些事情失败时，你就会知道它失败的确切位置以及问题所在，反对必须猜测。您将知道doMath是否存在问题，或者您的其他数学方法是否存在问题。它还允许您更轻松地重用您的方法用于其他事情，因此双赢
答案 1 :(得分：1)
考虑将输入，计算和输出放入（非静态）方法，这将使逻辑测试成为可能：
//This program performs basic math operations such as :- +,-,*,/
public class Calculator {
double number1, number2;
String Mathoperation;
Calculator()
{
//you need to remove input and calculation logic from constructor,
//to avoid running it when constructing this object for testing.
}
public void run() {
getInput();
double result = doMath(Mathoperation, number1, number2 );
System.out.println("Your answer is " + result );
}
private void getInput() {
Scanner scannerObject = new Scanner(System.in);
System.out.println("Enter first number");
number1 = scannerObject. nextDouble();
System.out.println("Enter second number");
number2 = scannerObject. nextDouble();
Scanner UserInput = new Scanner(System.in);
System.out.println("\nHere are your options:");
System.out.println("\n1. Addition, 2. Subtraction, 3. Divison, 4. Multiplication");
Mathoperation = UserInput.next();
}
/**
*@param mathoperation
*/
public double doMath(String mathoperation, double number1, double number2) {
switch (mathoperation)
{
case "1":
return (number1 + number2);
case "2":
return (number1 - number2);
case "3":
return (number1 / number2);
case "4":
return (number1 * number2);
default:
throw new IllegalStateException("mathoperation is not valid");
}
}
public static void main(String[] args)
{
Calculator calc = new Calculator();
calc.run();
}
}
这是一个非常简单的JUnit测试示例：
public class CalculatorTest {
/**
* Test method for {@link Calculator#doMath(java.lang.String, double, double)}.
*/
@Test
public void testDoMath() {
Calculator calc = new Calculator();
assertTrue(calc.doMath("1", 5, 7) == 12.0);
assertTrue(calc.doMath("2", 5, 7) == -2.0);
assertTrue(calc.doMath("3", 5, 7) == (5.0/7.0));
assertTrue(calc.doMath("4", 5, 7) == (5.0*7.0));
}
}
答案 2 :(得分：0)
要编写单元测试，您通常必须拥有要测试的API部分。在您的情况下，一切都在收集用户输入的主要方法中，因此很难测试。您应该提取类似于返回答案的double performOperation(number, number, operation)方法。然后，您可以使用此方法的不同输入编写JUnit测试。