[英]JUnit right way of test expected exceptions
Hello guys I was wondering if this way of testing my exception is ok, i have this exception i need to throw in the second test annotation, im receiving as result a red evil bar, and a succeed and a failure, as you can guess the failure is my concern, i have a fail(); 大家好我想知道这种测试我的异常的方法是否正常,我有这个例外我需要抛出第二个测试注释,我接收结果是一个红色的邪恶吧,一个成功和一个失败,你可以猜到失败是我关心的,我有失败(); there but the reason is because i read thats the way to test the exception and now im confused.
但原因是因为我读到了测试异常的方法,现在我很困惑。
Also i have to say im willin get the green bar because im expecting the exception, but i dont know if failure is the right way to see the answer of the expected exception. 此外,我不得不说im willin得到绿色条,因为我期待异常,但我不知道失败是否是正确的方式来看到预期的异常的答案。
Also if you had any advice, I would appreciate it 如果您有任何建议,我将不胜感激
@Before
public void setUp() throws Exception {
LogPack.logPacConfig(Constants.LOGGING_FILE);
gtfri = "+RESP:GTFRI,380502,869606020101881,INCOFER-gv65,,10,1,1,0.0,0,888.1,-84.194560,9.955602,20170220074514,,,,,,0.0,,,,100,210100,,,,20170220074517,40A2$";
weirdProtocol = "+RESP:GRI,380502,869606020101881,INCOFER-gv65,,10,1,1,0.0,0,888.1,-84.194560,9.955602,20170220074514,,,,,,0.0,,,,100,210100,,,,20170220074517,40A2$";
factory = new LocomotiveFactory();
}
@Test
public void GTFRICreationTester_shouldPass() throws TramaConProtolocoloDesconocido {
assertTrue(factory.createLocomotive(gtfri, false, new Date()) instanceof LocomotiveGTFRI);
}
@Test(expected = TramaConProtolocoloDesconocido.class)
public void GTFRICreationTester_shouldFail() {
try {
factory.createLocomotive(weirdProtocol, false, new Date());
fail("Expected an TramaConProtolocoloDesconocido");
} catch (TramaConProtolocoloDesconocido e) {
//assertSame("exception thrown as expected", "no se conoce el protocolo dado para la creacion de este factory", e.getMessage());;
}
}
There is 3 most common ways to test expected exception: 测试预期异常有3种最常用的方法:
First one is the most common way, but you can test only the type of expected exception with it. 第一种方法是最常用的方法,但您只能使用它来测试预期异常的类型。 This test will fail if
ExceptionType
won't be thrown: 如果不抛出
ExceptionType
则此测试将失败:
@Test(expected = ExceptionType.class)
public void testSomething(){
sut.doSomething();
}
Also you cannot specify the failure message using this approach 此外,您无法使用此方法指定失败消息
The better option is to use ExpectedException JUnit @Rule . 更好的选择是使用ExpectedException JUnit @Rule 。 Here you can assert much more for expected exception
在这里,您可以为预期的异常断言更多
@Rule
public ExpectedException thrown = ExpectedException.none();
@Test
public void testSomething(){
thrown.expect(ExceptionType.class);
thrown.expectMessage("Error message");
thrown.expectCause(is(new CauseOfExeption()));
thrown.reportMissingExceptionWithMessage("Exception expected");
//any other expectations
sut.doSomething();
}
The third option will allow you to do the same as with using ExpectedException @Rule, but all the assertion should be written manually. 第三个选项将允许您执行与使用ExpectedException @Rule相同的操作,但所有断言都应手动编写。 However the advantage of this method is that you can use any custom assertion and any assertion library that you want:
但是,此方法的优点是您可以使用任何自定义断言和所需的任何断言库:
@Test
public void testSomething(){
try{
sut.doSomething();
fail("Expected exception");
} catch(ExceptionType e) {
//assert ExceptionType e
}
}
You can use ExpectedException which can provide you more precise information about the exception expected to be thrown with the ability to verify error message, as follows: 您可以使用ExpectedException ,它可以为您提供有关预期抛出的异常的更精确信息,并具有验证错误消息的能力,如下所示:
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;
import org.junit.runner.RunWith;
public class TestClass {
@Rule
public ExpectedException expectedException = ExpectedException.none();
@Test
public void GTFRICreationTester_shouldFail() {
expectedException.expect(TramaConProtolocoloDesconocido.class);
factory.createLocomotive(weirdProtocol, false, new Date());
}
}
To expolore more about it, you can refer to the blog written by me here - Expected Exception Rule and Mocking Static Methods – JUnit 要更多地了解它,你可以参考我在这里写的博客 - 预期的异常规则和模拟静态方法 - JUnit
if your are using java 8, I would recommend to go for the AssertJ library 如果您使用的是java 8,我建议您去AssertJ库
public void GTFRICreationTester_shouldFail() {
assertThatExceptionOfType(EXCEPTION_CLASS).isThrownBy(() -> { factory.createLocomotive(weirdProtocol, false, new Date()) })
.withMessage("MESSAGE")
.withMessageContaining("MESSAGE_CONTAINING")
.withNoCause();
}
with that solution you can at one verify exception type, with message etc. 使用该解决方案,您可以在一个验证异常类型,消息等。
for more reading, take a look at: http://joel-costigliola.github.io/assertj/assertj-core-features-highlight.html#exception-assertion 欲了解更多信息,请查看: http : //joel-costigliola.github.io/assertj/assertj-core-features-highlight.html#exception-assertion
You don't need to catch the Exception
with try-catch
您不需要使用
try-catch
Exception
@Test(expected = TramaConProtolocoloDesconocido.class)
public void GTFRICreationTester_shouldFail() {
factory.createLocomotive(weirdProtocol, false, new Date());
}
If we suppose that factory.createLocomotive(weirdProtocol, false, new Date())
throws the exception
when you apply a scenario that makes the exception
thrown. 如果我们假设
factory.createLocomotive(weirdProtocol, false, new Date())
抛出exception
,当你申请一个场景,使exception
抛出。
void createLocomotive(param...) {
//something...
throw new TramaConProtolocoloDesconocido();
}
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