java 使用 void 方法进行 Junit 测试
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Junit Testing with void method
提问by Seeruttun Kervin
I have to create a JUnit test for the following class, but I cannot do the test for the method deposit.
我必须为以下类创建一个 JUnit 测试，但我无法对方法进行测试deposit。
public class Account {
private int balance;
private float Interest_Rate =10;
public Account() {
this.balance = 0;
}
public void deposit(int amount) {
balance = balance+amount;
}
}
@Test
public void testdeposit() {
Account i = new Account();
assertEquals("Result",75,i.deposit(25));
}
回答by davidxxx
You could add a getBalance()method in the Accountclass :
您可以getBalance()在Account类中添加一个方法：
public int getBalance(){
return balance;
}
And use it to do the assertion :
并用它来做断言：
@Test
public void deposit(){
Account i = new Account();
i.deposit(25)
assertEquals("Result",25, i.getBalance());
}
Generally adding methods that are only used during unit testing may be evaluated and discussed.
But here getBalance()appears as unavoidable.
通常可以评估和讨论添加仅在单元测试期间使用的方法。
但这里getBalance()似乎是不可避免的。
回答by Bor Laze
Testing private fields/methods does not have sense.
测试私有字段/方法没有意义。
In your case, balanceis 'write-only' variable; it should have public accessor (as written above), or field should be used in other methods like
在您的情况下，balance是“只写”变量；它应该具有公共访问器（如上所述），或者应该在其他方法中使用字段，例如
public int income() {
if(balance == 0 ) return 0;
if(balance < 100) return 10;
if(balance < 1000) return 15;
return 20;
}
In this case your test should be like
在这种情况下，您的测试应该类似于
@Test
public void deposit(){
Account acc = new Account();
acc.deposit(150);
assertEquals("Result ", 15, acc.income());
}
Don't test implementation; test interface.
不要测试实现；测试界面。
回答by NachoGobet
You could have a System.out.println in the method and tell the JUnit test to ask for stdout:
您可以在方法中有一个 System.out.println 并告诉 JUnit 测试请求 stdout：
private final ByteArrayOutputStream outContent = new ByteArrayOutputStream();
and then
接着
@Before
public void setUpStreams() {
System.setOut(new PrintStream(outContent));
}
@After
public void cleanUpStreams() {
System.setOut(null);
}
finally
最后
assertEquals(<here goes your expected string>, outContent.toString());
