In exception handling, it is known that, if the super class method does not declare an exception, subclass overridden method cannot declare the checked exception but it can declare unchecked exception. Why so? consider the following example :
import java.io.*;
class Parent {
void msg() {
System.out.println("parent");
}
}
class TestExceptionChild extends Parent {
void msg() throws IOException {
System.out.println("TestExceptionChild");
}
public static void main(String args[]) {
Parent p = new TestExceptionChild();
p.msg();
}
}
What I have tried:
We get compilation error here. If I need to read a file in the overridden method "msg", then I have to mention "throws IOException" there. But java doesn't allow them. Can anyone explain this?
This happens because you are violating the Liskov substitution principle, i.e: you can't replace the instance of the superclass with one of the subclass because you are modifying the signature of the method msg in the father superclass.
In the more general class, the method msg doesn't throw any exception, and you want to modify the signature in the subclass, which is obviously unallowed, because it violates the contract of the override principal.
You need remember one thing that if you are using throws keyword than any exception arises will be forwarded into the calling chain and in case of overriding at compilation time compiler checks weather the overridden method is there in parent or not and JVM execute the child class method.
So,basically from parent the child method is called and hence it should be capable of handling checked exception if child method throws any exception otherwise CE..
I Hope It Helps :)
Related
I have parent router that calls other routers. The parent router has all the exception handling logic. In all child routers, on exception, I want to just add properties in the exchange object and leave the actual exception handling in the parent(main) router.
Example:
public class ParentRouter extends RouteBuilder {
#Override
public void configure() throws Exception {
onException(CustomException.class)
.process(new ExceptionProcessor())
.handled(true);
from("direct:parent-route").to("direct:child-route");
from("direct:child-route")
.onException(CustomException.class)
.process(new Processor(){
#Override
public process(Exchange exchange){
exchange.setProperty("childExceptionFlg", "true");
}
});
}
As per my requirement, when CustomExpection is thrown in the child router, it should add a property to the exchange object and the final handling code needs to be executed in the ExceptionProcessor in the parent router.
What you try to achieve can be done using routes dedicated to error handling that call each other (child error handler route calls parent error handler route) or at least a route for the main error handler that is called by the exception policy of your child routes.
Something like:
// The main logic of the main exception policy is moved to a dedicated
// route called direct:main-error-handler
onException(CustomException.class)
.to("direct:main-error-handler")
.handled(true);
from("direct:parent-route").to("direct:child-route");
from("direct:child-route")
.onException(CustomException.class)
// Set the exchange property childExceptionFlg to true
.setProperty("childExceptionFlg", constant("true"))
// Call explicitly the main logic of the the main exception policy once
// the property is set
.to("direct:main-error-handler")
// Flag the exception as handled
.handled(true)
.end()
// Throw a custom exception to simulate your use case
.throwException(new CustomException());
from("direct:main-error-handler")
.log("Property childExceptionFlg set to ${exchangeProperty.childExceptionFlg}");
Result:
INFO route3 - Property childExceptionFlg set to true
In the following test code, I make a declaration: when the get() method is called with argument 0, then an exception should be thrown out. In my opinion, if the argument is not 0, the exception should not be thrown out. But, the test was passed. That means get(1) has caused an exception was thrown. Is this a bug of Mockito?
#RunWith(MockitoJUnitRunner.class)
public class MockitoTest {
#Mock
private List<Integer> mockedList;
#Test(expected = Exception.class)
public void test() throws Exception {
when(mockedList.get(0)).thenThrow(new Exception());
mockedList.get(1);
}
}
You set up your test incorrectly and misinterpreted the outcome of your test.
The problem lies in the line:
when(mockedList.get(0)).thenThrow(new Exception());
The signature of "get" method does not allow checked excetions.
Thus, when you pass a checked exception to thenThrow, Mockito rightfully reports it with:
org.mockito.exceptions.base.MockitoException:
Checked exception is invalid for this method!
Invalid: java.lang.Exception
Thus the exception reported is MockitoException, not the Exception you passed to thenThrow. It is thrown even if you omit a call to mockedList.get(1);
To fix, use a RuntimeException, preferrably one that can be reported by get.
when(mockedList.get(0)).thenThrow(new IndexOutOfBoundsException());
Note that you stub a call that is not made afterwards, you need to use a lenient mock with #Mock(lenient = true), otherwise Mockito will report a org.mockito.exceptions.misusing.UnnecessaryStubbingException
In actframework, we can use #catch to handle exception, but it's only working in current class and parent class. What can i do if i want to create a global exception handler, just like #ExceptionHandler in SpringBoot?
Just add #Global annotation to your #Catch method, e.g.
public class AppExceptionHandler {
#Global
#Catch(value = Throwable.class, priority = 1)
public void logThrowable(Throwable throwable) {
AppEntry.LOGGER.error(throwable, "Global Exception Handler: %s", throwable.getMessage());
}
}
With the given code above, it will catch exception triggered in any request handler, e.g,
You can use #ControllerAdvice to create Global Exception Handler in spring boot. Below answer has sample code snippet that explains the same.
#ControllerAdvice even by setting the highest precedense for RestControllers not working as it should
Is there any hook in Junit5 that reacts to fails in #Before* methods?
I use a #BeforeAll method to init environment for my tests. But this initialization may sometimes fail. I want to dump the environment, to find out whats wrong, but I need to do it before #After* methods are called, which will clear the environment and destroy all info.
We're talking about dozens of these #BeforeAll methods across the test suite, so doing it manually inside each method is not an option.
I've already tried these, but no luck:
TestWatcher does not work for this, since it only fires if an actual test is executed.
TestExecutionListener.executionFinished looks promising, but it fires after all the #After methods, which is too late for me.
I even tried to do it inside the #AfterAll cleanup methods, before the actual cleanup. But found no way to detect which tests were executed or if anything failed.
Any ideas?
I assume by "fails in #Before* methods" you mean exceptions? If that is the case, you could leverage the extension model as follows:
#ExtendWith(DumpEnvOnFailureExtension.class)
class SomeTest {
static class DumpEnvOnFailureExtension implements LifecycleMethodExecutionExceptionHandler {
#Override
public void handleBeforeAllMethodExecutionException(final ExtensionContext context, final Throwable ex)
throws Throwable {
System.out.println("handleBeforeAllMethodExecutionException()");
// dump env
throw ex;
}
}
#BeforeAll
static void setUpOnce() {
System.out.println("setUpOnce()");
throw new RuntimeException();
}
#Test
void test() throws Exception {
// some test
}
#AfterAll
static void tearDownOnce() {
System.out.println("tearDownOnce()");
}
}
The log will be:
setUpOnce()
handleBeforeAllMethodExecutionException()
tearDownOnce()
That is, the extension is notified if the #BeforeAll method fails with an exception. (Note that this is just an MWE, for the actual implementation you would extract DumpEnvOnFailureExtension and use it wherever needed.)
For further information, check out section "Exception Handling" in the user guide.
public static ResponseBean call(Bean bean) throws Exception {
// statements...
IgnoreCall.ignoreMethodCall(bean);
// statements...
// return
}
With the code snippet above, is it possible to test the method ignoring invocation of IgnoreCall.ignoreMethod(Bean) without needing to place the entire statement under a boolean condition?
Here's the unit test code snippet:
#RunWith(PowerMockRunner.class)
#PrepareTest
public ClassHelperTest {
#Test
public void testCall() throws Excpetion {
// stubbing...
ResponseBean responseBean = ClassHelper.call(bean);
// verify/ies
// assert/s
}
}
Notes:
Refactoring ClassHelper.call(Bean) should be avoided. Even with a bad OO design, refactoring is costly.
Method signature is locked unless another pattern is applicable for replacement.
Tried using Mockito.when and PowerMockito.when on the target static method, stubbing didn't work on run-time debug.
As your comments indicate that changing your production code is not possible, you "simply" have to dive into the static-mocking aspects of PowerMock; as outlined here for example.
Basically you need to enable IgnoreCall for static mocking; and then you make calls to ignoreMethodCall() a no-op.
But as you keep asking: the core problem with your question is the fact that you want to mock out a static method that is void. I have a complete example below, but before that some explanations.
The point is: you call a method for two reasons:
It has a side effect
It returns a value, and maybe, causes a side effect, too
A void method can only be called for side effects. And the thing is: when you do static mocking, then that works on class level.
Meaning: you instruct PowerMock to "prevent" any of the static methods of some class from execution; you simply "erase" the side effects of all those static methods! So, by telling PowerMock to do those static mocks, all void methods are already "gone".
But as said, you might also call methods for their return value. And then is when the when() method of Mockito kicks in. You use that method to say: when that value-returning method is invoked, then do this or that.
Long story short; here is a [mcve] using the elements you asked for:
package ghostcat.test;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
class IgnoreCall {
public static void ignoreMethodCall(Object o) {
System.out.println("SHOULD NOT SHOW UP: " + o);
}
}
class CuT {
public static Object call(Object bean) {
System.out.println("statement1");
IgnoreCall.ignoreMethodCall(bean);
System.out.println("statement2");
return "whatever";
}
}
#RunWith(PowerMockRunner.class)
#PrepareForTest(IgnoreCall.class)
public class PMTest {
#Test
public void test() {
PowerMockito.mockStatic(IgnoreCall.class);
CuT.call("yeha");
}
}
As in your example ... there is IgnoreCall; used within that a static method that I just called "call".
This prints:
statement1
statement2
When I go in and comment out
// PowerMockito.mockStatic(IgnoreCall.class);
It prints:
statement1
SHOULD NOT SHOW UP: yeha
statement2
So, a simple example that should tell you exactly what you need to do.
I worked with eclipse neon, IBM java8 JDK, and simply imported all the JARs from powermock-mockito-junit-1.6.6.zip into my test project.