本文介绍如何使用TestNG进行异常测试，包括验证抛出的异常类型及异常消息。通过示例展示了如何指定期望的异常，并使用正则表达式验证异常消息。
以下内容引自: https://howtodoinjava.com/testng/testng-expected-exception-and-expected-message-tutorial/
TestNG – Expected Exception and Expected Message Tutorial
While writing unit tests there can be certain scenarios where we need to verify that an exception is being thrown by the program during execution. TestNG provides a feature to test such scenarios by allowing the user to specify the type of exceptions that are expected to be thrown by a test methodduring execution. It supports multiple values being provided for verification. If the exception thrown by the test is not part of the user entered list, the test method will be marked as failed.
Let’s create a sample test and learn how exception test works in TestNG.
@Test ( expectedExceptions = { IOException.class, NullPointerException.class } )
Let’s see an example to understand it better.
Example of Expected Exception Test
In below test, we have two test methods i.e. exceptionTestOne() and exceptionTestTwo(). Here exceptionTestOne() throws IOException where as exceptionTestTwo() throws Exception. The expected exception to validate while running these tests is mentioned using the expectedExceptions attribute value while using the Test annotation.
public
class
ExceptionTestDemo
{
@Test
(expectedExceptions = { IOException.
class
})
public
void
exceptionTestOne()
throws
Exception {
throw
new
IOException();
}
@Test
(expectedExceptions = { IOException.
class
, NullPointerException.
class
})
public
void
exceptionTestTwo()
throws
Exception {
throw
new
Exception();
}
}
|
Output of above test run is given below:
[TestNG] Running: C:\Users\somepath\testng-customsuite.xml
PASSED: exceptionTestOne
FAILED: exceptionTestTwo
org.testng.TestException:
Expected exception java.io.IOException but got org.testng.TestException:
Expected exception java.io.IOException but got java.lang.Exception
at org.testng.internal.Invoker.handleInvocationResults(Invoker.java:
1497
)
at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:
1245
)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:
127
)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:
111
)
at org.testng.TestRunner.privateRun(TestRunner.java:
767
)
at org.testng.TestRunner.run(TestRunner.java:
617
)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:
334
)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:
329
)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:
291
)
at org.testng.SuiteRunner.run(SuiteRunner.java:
240
)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:
52
)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:
86
)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:
1224
)
at org.testng.TestNG.runSuitesLocally(TestNG.java:
1149
)
at org.testng.TestNG.run(TestNG.java:
1057
)
at org.testng.remote.RemoteTestNG.run(RemoteTestNG.java:
111
)
at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:
204
)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:
175
)
Caused by: org.testng.TestException:
Expected exception java.io.IOException but got java.lang.Exception
at org.testng.internal.Invoker.handleInvocationResults(Invoker.java:
1497
)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:
754
)
at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:
901
)
at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:
1231
)
...
16
more
Caused by: java.lang.Exception
at com.howtodoinjava.test.ExceptionTestDemo.exceptionTestTwo(ExceptionTestDemo.java:
16
)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:
39
)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:
25
)
at java.lang.reflect.Method.invoke(Method.java:
597
)
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:
84
)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:
714
)
...
18
more
===============================================
Default test
Tests run:
2
, Failures:
1
, Skips:
0
===============================================
|
As you can see from the test results, exceptionTestTwo() was marked as failed by TestNG during execution. The test failed because the exception thrown by the said method does not match the exception list provided in the expectedExceptions list.
Example of Expected Exception Test with Verifying Message
You can also verify a test based on the exception message that was thrown by the test. Regular expression can also be used to verify the error message, this can be done using .*. Depending upon the position of the regular expression we can use it to do pattern matching such as starts-with, contains, and ends-with while verifying the exception message.
Let’s learn how to write a exception test based on the exception message thrown.
public
class
ExceptionTestDemo
{
@Test
(expectedExceptions = { IOException.
class
}, expectedExceptionsMessageRegExp =
"Pass Message test"
)
public
void
exceptionTestOne()
throws
Exception {
throw
new
IOException(
"Pass Message test"
);
}
@Test
(expectedExceptions = { IOException.
class
}, expectedExceptionsMessageRegExp =
".* Message .*"
)
public
void
exceptionTestTwo()
throws
Exception {
throw
new
IOException(
"Pass Message test"
);
}
@Test
(expectedExceptions = { IOException.
class
}, expectedExceptionsMessageRegExp =
"Pass Message test"
)
public
void
exceptionTestThree()
throws
Exception {
throw
new
IOException(
"Fail Message test"
);
}
}
|
Output of above test run is given below:
[TestNG] Running: C:\Users\somepath\testng-customsuite.xml
PASSED: exceptionTestOne
PASSED: exceptionTestTwo
FAILED: exceptionTestThree
org.testng.TestException:
Expected exception java.io.IOException but got org.testng.TestException:
The exception was thrown with the wrong message: expected
"Pass Message test"
but got
"Fail Message test"
at org.testng.internal.Invoker.handleInvocationResults(Invoker.java:
1497
)
at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:
1245
)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:
127
)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:
111
)
at org.testng.TestRunner.privateRun(TestRunner.java:
767
)
at org.testng.TestRunner.run(TestRunner.java:
617
)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:
334
)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:
329
)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:
291
)
at org.testng.SuiteRunner.run(SuiteRunner.java:
240
)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:
52
)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:
86
)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:
1224
)
at org.testng.TestNG.runSuitesLocally(TestNG.java:
1149
)
at org.testng.TestNG.run(TestNG.java:
1057
)
at org.testng.remote.RemoteTestNG.run(RemoteTestNG.java:
111
)
at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:
204
)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:
175
)
Caused by: org.testng.TestException:
The exception was thrown with the wrong message: expected
"Pass Message test"
but got
"Fail Message test"
at org.testng.internal.Invoker.handleInvocationResults(Invoker.java:
1481
)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:
754
)
at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:
901
)
at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:
1231
)
...
16
more
Caused by: java.io.IOException: Fail Message test
at com.howtodoinjava.test.ExceptionTestDemo.exceptionTestThree(ExceptionTestDemo.java:
21
)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:
39
)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:
25
)
at java.lang.reflect.Method.invoke(Method.java:
597
)
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:
84
)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:
714
)
...
18
more
===============================================
Default test
Tests run:
3
, Failures:
1
, Skips:
0
===============================================
|
In above test methods exceptionTestThree() failed because expected message didn’t matched.
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