Java 我可以在一个测试方法中测试多个抛出的异常吗?
我有一个很好的指定接口,并以此为基础编写JUnit测试:Java 我可以在一个测试方法中测试多个抛出的异常吗?,java,testing,exception-handling,junit,junit4,Java,Testing,Exception Handling,Junit,Junit4,我有一个很好的指定接口,并以此为基础编写JUnit测试: public interface ShortMessageService { /** * Creates a message. A message is related to a topic * Creates a date for the message * @throws IllegalArgumentException, if the message is longer then 255 c
public interface ShortMessageService {
/**
* Creates a message. A message is related to a topic
* Creates a date for the message
* @throws IllegalArgumentException, if the message is longer then 255 characters.
* @throws IllegalArgumentException, if the message ist shorter then 10 characters.
* @throws IllegalArgumentException, if the user doesn't exist
* @throws IllegalArgumentException, if the topic doesn't exist
* @throws NullPointerException, if one argument is null.
* @param userName
* @param message
* @return ID of the new created message
*/
Long createMessage(String userName, String message, String topic);
[...]
}
正如您所看到的,实现可以抛出各种异常,我必须为这些异常编写测试。我目前的方法是为接口中指定的一个可能的异常编写一个测试方法,如下所示:
public abstract class AbstractShortMessageServiceTest
{
String message;
String username;
String topic;
/**
* @return A new empty instance of an implementation of ShortMessageService.
*/
protected abstract ShortMessageService getNewShortMessageService();
private ShortMessageService messageService;
@Rule
public ExpectedException thrown = ExpectedException.none();
@Before
public void setUp() throws Exception
{
messageService = getNewShortMessageService();
message = "Test Message";
username = "TestUser";
topic = "TestTopic";
}
@Test
public void testCreateMessage()
{
assertEquals(new Long(1L), messageService.createMessage(username, message, topic));
}
@Test (expected = IllegalArgumentException.class)
public void testCreateMessageUserMissing() throws Exception
{
messageService.createMessage("", message, topic);
}
@Test (expected = IllegalArgumentException.class)
public void testCreateMessageTopicMissing() throws Exception
{
messageService.createMessage(username, message, "");
}
@Test (expected = IllegalArgumentException.class)
public void testCreateMessageTooLong() throws Exception
{
String message = "";
for (int i=0; i<255; i++) {
message += "a";
}
messageService.createMessage(username, message, topic);
}
@Test (expected = IllegalArgumentException.class)
public void testCreateMessageTooShort() throws Exception
{
messageService.createMessage(username, "", topic);
}
@Test (expected = NullPointerException.class)
public void testCreateMessageNull() throws Exception
{
messageService.createMessage(username, null, topic);
}
[...]
}
公共抽象类AbstractShortMessageServiceTest
{
字符串消息;
字符串用户名;
字符串主题;
/**
*@返回ShortMessageService实现的新空实例。
*/
受保护的抽象ShortMessageService getNewShortMessageService();
私人短信服务;
@统治
抛出公共ExpectedException=ExpectedException.none();
@以前
public void setUp()引发异常
{
messageService=getNewShortMessageService();
message=“测试消息”;
username=“TestUser”;
topic=“TestTopic”;
}
@试验
public void testCreateMessage()
{
assertEquals(新长(1L),messageService.createMessage(用户名,消息,主题));
}
@测试(预期=IllegalArgumentException.class)
public void testCreateMessageUserMissing()引发异常
{
messageService.createMessage(“,消息,主题);
}
@测试(预期=IllegalArgumentException.class)
public void testCreateMessageTopicMissing()引发异常
{
messageService.createMessage(用户名,message,“”);
}
@测试(预期=IllegalArgumentException.class)
public void TestCreateMessageToolLong()引发异常
{
字符串消息=”;
对于(inti=0;i来说,将它们组合在一个方法中可能不是最好的主意,因为您不知道哪个测试用例抛出了哪个异常
例如,如果你有这条线
messageService.createMessage(username, null, topic);
它应该抛出一个NullPointerException
,但是它却抛出了一个IllegalArgumentException
,您不希望这算成功
如果您想在一个测试用例中测试该方法的所有异常,那么一个好的替代方法是将每个异常测试包装在try..catch块中
例如,你可以
@Test
public void testCreateMessageExceptions() {
// test #1: a null message
try {
messageService.createMessage(username, null, topic);
// if it got this far, that's a problem!
fail();
} catch(NullPointerException e) {
// great, that's what it's meant to do! continue testing
} catch(Exception e) {
// if it threw the wrong type of exception, that's a problem!
fail();
}
// test #2: an empty user
try {
messageService.createMessage("", message, topic);
fail();
} catch(IllegalArgumentException e) {
} catch(Exception e) {
fail();
}
// ...
}
不幸的是,@Test注释不允许捕获多个异常类型(api引用)
作为第一种选择,我主张迁移到TestNG。如果您的团队不允许这样做,那么在JUnit中您可以做的事情很少
一定要使用参数化测试用例,这样就不必为每个测试用例()编写一个测试函数
按异常类型对测试数据进行分组
@Test (expected = IllegalArgumentException.class)
public void testIllegalArgumentException(String username, String message, String topic) {}
@Test (expected = NullPointerException.class)
public void testNullPointerException(String username, String message, String topic) {}
结合方法签名中的异常类型。(这是我推荐的)下面的大致轮廓
public void testException(String username, String message, String topic, Class<? extends Exception>[] expectedExceptionClasses) {
try {
// exception throwing code
} catch (Exception e) {
boolean found = false;
for (Class<?> expectedException : expectedExceptions) {
if (e instanceof expectedException) {
found = true;
}
}
if (found) {
return;
}
}
Assert.fail();
}
这很好,但您可以使用ExpectedException规则对此进行改进:
@Test (expected = Exception.class)
public void testException(String username, String message, String topic) {}