I am new to Apache Camel and trying to receive a simple SNMP trap.
I have the Maven project set up with camel-core and org.apache.servicemix.bundles.snmp4j.
I have not been able to find any SNMP examples, but based on other examples I have come up with this Main class:
public class Main {
public static Processor myProcessor = new Processor() {
public void process(Exchange arg0) throws Exception {
// save to database
}
};
public static void main(String[] args) {
CamelContext context = new DefaultCamelContext();
context.addComponent("snmp", new SnmpComponent());
RouteBuilder builder = new RouteBuilder() {
public void configure() {
from("snmp:127.0.0.1:162?protocol=udp&type=TRAP").process(myProcessor);
}
};
try {
context.addRoutes(builder);
context.start();
} catch (Exception e) {
e.printStackTrace();
}
}
}
However when I run it in Eclipse as Java application it just exits after running for half a second. I was expecting it to keep running and listening to 127.0.0.1:162 ...
Any help is greatly appreciated
One way to at least pick up a trap and print to System.out is like so:
public class SNMPTrap {
private Main main;
public static void main(String[] args) throws Exception {
SNMPTrap snmpTrap = new SNMPTrap();
snmpTrap.boot();
}
#SuppressWarnings("deprecation")
public void boot() throws Exception {
main = new Main();
main.bind("snmp", new SnmpComponent());
main.addRouteBuilder(new MyRouteBuilder());
main.addMainListener(new Events());
System.out.println("Starting SNMPTrap. Use ctrl + c to terminate the JVM.\n");
main.run();
}
private static class MyRouteBuilder extends RouteBuilder {
#Override
public void configure() throws Exception {
from("snmp:127.0.0.1:162?protocol=udp&type=TRAP").process(myProcessor)
.bean("snmp");
}
}
public static Processor myProcessor = new Processor() {
public void process(Exchange trap) throws Exception {
System.out.println(trap.getIn().getBody(String.class));
// Save to DB or do other good stuff
}
};
public static class Events extends MainListenerSupport {
#Override
public void afterStart(MainSupport main) {
System.out.println("SNMPTrap is now started!");
}
#Override
public void beforeStop(MainSupport main) {
System.out.println("SNMPTrap is now being stopped!");
}
}
}
However, I get warning that Main which is part of Camel core is deprecated now.
I'm trying to improve an existing system of automated Selenium test.
My goal is to repeat the tests that fails because of connections problem.
I've found and tried to follow this thread How to Re-run failed JUnit tests immediately? that revealed itself quite useful.
In my case the suite is composed by classes, so I've tried to substitute #Rule with #ClassRule, in order to repeat for each try also the #Before and #After parts.
I'm sorry for my ignorance, but where am I supposed to place this rule? In my Suite class? Or in the Classes representing the test?
I am the original answerer of How to Re-run failed JUnit tests immediately?
If I understand correctly, the problem that you are having is due to the #Before being executed before the code in the RetryRule, and the #After being executed afterwards.
So your current behaviour is something like:
#Before
#Retry
test code
#Retry
#After
But you can implement your #Before and #After as a rule - there is a rule ExternalResource which does exactly that. You would implement #Before and #After as a rule:
#Rule public ExternalResource beforeAfter = new ExternalResource() {
public void before() {
// code that was in #Before
}
public void after() {
// code that was in #After
}
}
Then you don't need the #Before and #After. You can then chain these rules using RuleChain. This forces an order of execution to your rules:
#Rule public RuleChain chain= RuleChain
.outerRule(new LoggingRule("outer rule")
.around(new LoggingRule("middle rule")
.around(new LoggingRule("inner rule");
so your final solution would be something like:
private ExternalResource beforeAfter = ...
private RetryRule retry = ...
#Rule public RuleChain chain = RuleChain
.outerRule(retry)
.around(beforeAfter);
Note that if you are using RuleChain, you no longer need the #Rule annotation on the ExternalResource and RetryRule, but you do on the RuleChain.
Here is my solution based on the one mentionned in the question.
It's a combinaison of a #Rule, FailedRule and a #ClassRule, RetryRule
public class RetryTest
{
public static class FailedRule implements TestRule
{
#Override
public Statement apply(final Statement base, final Description description)
{
return new Statement()
{
#Override
public void evaluate() throws Throwable
{
try
{
base.evaluate();
}
catch (Throwable t)
{
System.out.println(description.getDisplayName() + " failed");
retry.setNotGood();
if (retry.isLastTry())
{
System.out.println("No more retry !");
throw t;
}
else
{
System.out.println("Retrying.");
}
}
}
};
}
}
public static class RetryRule implements TestRule
{
private int retryCount, currentTry;
private boolean allGood = false;
public RetryRule(int retryCount)
{
this.retryCount = retryCount;
this.currentTry = 1;
}
public boolean isLastTry()
{
return currentTry == retryCount;
}
public void setNotGood()
{
allGood = false;
}
public Statement apply(final Statement base, final Description description)
{
return new Statement()
{
#Override
public void evaluate() throws Throwable
{
// implement retry logic here
for (; currentTry <= retryCount && !allGood; currentTry++)
{
allGood = true;
System.out.println("Try #" + currentTry);
base.evaluate();
}
}
};
}
}
#ClassRule
public static RetryRule retry = new RetryRule(3);
#Rule
public FailedRule onFailed = new FailedRule();
#BeforeClass
public static void before()
{
System.out.println("Before...");
}
#AfterClass
public static void after()
{
System.out.println("...After\n");
}
#Test
public void test1()
{
System.out.println("> test1 running");
}
#Test
public void test2()
{
System.out.println("> test2 running");
Object o = null;
o.equals("foo");
}
}
It gives :
Try #1
Before...
> test1 running
> test2 running
test2(RetryTest) failed
Retrying.
...After
Try #2
Before...
> test1 running
> test2 running
test2(RetryTest) failed
Retrying.
...After
Try #3
Before...
> test1 running
> test2 running
test2(RetryTest) failed
No more retry !
...After
If I am commenting the o.equals("foo"); in test2, everything runs fine in the firt try :
Try #1
Before...
> test1 running
> test2 running
...After
You decorate the test name itself with the #After or #Afterclass attributes:
#After
#Test
#Category(SmokeTests.class)
public void testProductPageOnly() throws TimeoutException {
//Some tests here.
}
#Afterclass
public static void SomeTest {
//Some test here.
}
Something to note, #Afterclass will always run; even if you are using a #Beforeclass that throws an exception.
May this can solve problem:
1) Test class should be inherited from junit.framework.TestCase
2) Run your tests with something like this
YourTestClass testClass = new YourTestClass();
TestResult result = testClass.run();
Enumeration<TestFailure> failures = result.failures();
if (result.failureCount() != 0)
{
TestFailure fail = failes.nextElement();
junit.framework.Test test = fail.failedTest();
test.run( result );
}
At the end result will contains last results of test running, so after analyzing what test was failed you can run it again.
I've got a few methods that should call System.exit() on certain inputs. Unfortunately, testing these cases causes JUnit to terminate! Putting the method calls in a new Thread doesn't seem to help, since System.exit() terminates the JVM, not just the current thread. Are there any common patterns for dealing with this? For example, can I subsitute a stub for System.exit()?
[EDIT] The class in question is actually a command-line tool which I'm attempting to test inside JUnit. Maybe JUnit is simply not the right tool for the job? Suggestions for complementary regression testing tools are welcome (preferably something that integrates well with JUnit and EclEmma).
Indeed, Derkeiler.com suggests:
Why System.exit() ?
Instead of terminating with System.exit(whateverValue), why not throw an unchecked exception? In normal use it will drift all the way out to the JVM's last-ditch catcher and shut your script down (unless you decide to catch it somewhere along the way, which might be useful someday).
In the JUnit scenario it will be caught by the JUnit framework, which will report that
such-and-such test failed and move smoothly along to the next.
Prevent System.exit() to actually exit the JVM:
Try modifying the TestCase to run with a security manager that prevents calling System.exit, then catch the SecurityException.
public class NoExitTestCase extends TestCase
{
protected static class ExitException extends SecurityException
{
public final int status;
public ExitException(int status)
{
super("There is no escape!");
this.status = status;
}
}
private static class NoExitSecurityManager extends SecurityManager
{
#Override
public void checkPermission(Permission perm)
{
// allow anything.
}
#Override
public void checkPermission(Permission perm, Object context)
{
// allow anything.
}
#Override
public void checkExit(int status)
{
super.checkExit(status);
throw new ExitException(status);
}
}
#Override
protected void setUp() throws Exception
{
super.setUp();
System.setSecurityManager(new NoExitSecurityManager());
}
#Override
protected void tearDown() throws Exception
{
System.setSecurityManager(null); // or save and restore original
super.tearDown();
}
public void testNoExit() throws Exception
{
System.out.println("Printing works");
}
public void testExit() throws Exception
{
try
{
System.exit(42);
} catch (ExitException e)
{
assertEquals("Exit status", 42, e.status);
}
}
}
Update December 2012:
Will proposes in the comments using System Rules, a collection of JUnit(4.9+) rules for testing code which uses java.lang.System.
This was initially mentioned by Stefan Birkner in his answer in December 2011.
System.exit(…)
Use the ExpectedSystemExit rule to verify that System.exit(…) is called.
You could verify the exit status, too.
For instance:
public void MyTest {
#Rule
public final ExpectedSystemExit exit = ExpectedSystemExit.none();
#Test
public void noSystemExit() {
//passes
}
#Test
public void systemExitWithArbitraryStatusCode() {
exit.expectSystemExit();
System.exit(0);
}
#Test
public void systemExitWithSelectedStatusCode0() {
exit.expectSystemExitWithStatus(0);
System.exit(0);
}
}
The library System Lambda has a method catchSystemExit.With this rule you are able to test code, that calls System.exit(...):
public class MyTest {
#Test
public void systemExitWithArbitraryStatusCode() {
SystemLambda.catchSystemExit(() -> {
//the code under test, which calls System.exit(...);
});
}
#Test
public void systemExitWithSelectedStatusCode0() {
int status = SystemLambda.catchSystemExit(() -> {
//the code under test, which calls System.exit(0);
});
assertEquals(0, status);
}
}
For Java 5 to 7 the library System Rules has a JUnit rule called ExpectedSystemExit. With this rule you are able to test code, that calls System.exit(...):
public class MyTest {
#Rule
public final ExpectedSystemExit exit = ExpectedSystemExit.none();
#Test
public void systemExitWithArbitraryStatusCode() {
exit.expectSystemExit();
//the code under test, which calls System.exit(...);
}
#Test
public void systemExitWithSelectedStatusCode0() {
exit.expectSystemExitWithStatus(0);
//the code under test, which calls System.exit(0);
}
}
Full disclosure: I'm the author of both libraries.
How about injecting an "ExitManager" into this Methods:
public interface ExitManager {
void exit(int exitCode);
}
public class ExitManagerImpl implements ExitManager {
public void exit(int exitCode) {
System.exit(exitCode);
}
}
public class ExitManagerMock implements ExitManager {
public bool exitWasCalled;
public int exitCode;
public void exit(int exitCode) {
exitWasCalled = true;
this.exitCode = exitCode;
}
}
public class MethodsCallExit {
public void CallsExit(ExitManager exitManager) {
// whatever
if (foo) {
exitManager.exit(42);
}
// whatever
}
}
The production code uses the ExitManagerImpl and the test code uses ExitManagerMock and can check if exit() was called and with which exit code.
You actually can mock or stub out the System.exit method, in a JUnit test.
For example, using JMockit you could write (there are other ways as well):
#Test
public void mockSystemExit(#Mocked("exit") System mockSystem)
{
// Called by code under test:
System.exit(); // will not exit the program
}
EDIT: Alternative test (using latest JMockit API) which does not allow any code to run after a call to System.exit(n):
#Test(expected = EOFException.class)
public void checkingForSystemExitWhileNotAllowingCodeToContinueToRun() {
new Expectations(System.class) {{ System.exit(anyInt); result = new EOFException(); }};
// From the code under test:
System.exit(1);
System.out.println("This will never run (and not exit either)");
}
One trick we used in our code base was to have the call to System.exit() be encapsulated in a Runnable impl, which the method in question used by default. To unit test, we set a different mock Runnable. Something like this:
private static final Runnable DEFAULT_ACTION = new Runnable(){
public void run(){
System.exit(0);
}
};
public void foo(){
this.foo(DEFAULT_ACTION);
}
/* package-visible only for unit testing */
void foo(Runnable action){
// ...some stuff...
action.run();
}
...and the JUnit test method...
public void testFoo(){
final AtomicBoolean actionWasCalled = new AtomicBoolean(false);
fooObject.foo(new Runnable(){
public void run(){
actionWasCalled.set(true);
}
});
assertTrue(actionWasCalled.get());
}
I like some of the answers already given but I wanted to demonstrate a different technique that is often useful when getting legacy code under test. Given code like:
public class Foo {
public void bar(int i) {
if (i < 0) {
System.exit(i);
}
}
}
You can do a safe refactoring to create a method that wraps the System.exit call:
public class Foo {
public void bar(int i) {
if (i < 0) {
exit(i);
}
}
void exit(int i) {
System.exit(i);
}
}
Then you can create a fake for your test that overrides exit:
public class TestFoo extends TestCase {
public void testShouldExitWithNegativeNumbers() {
TestFoo foo = new TestFoo();
foo.bar(-1);
assertTrue(foo.exitCalled);
assertEquals(-1, foo.exitValue);
}
private class TestFoo extends Foo {
boolean exitCalled;
int exitValue;
void exit(int i) {
exitCalled = true;
exitValue = i;
}
}
This is a generic technique for substituting behavior for test cases, and I use it all the time when refactoring legacy code. It not usually where I'm going to leave thing, but an intermediate step to get the existing code under test.
For VonC's answer to run on JUnit 4, I've modified the code as follows
protected static class ExitException extends SecurityException {
private static final long serialVersionUID = -1982617086752946683L;
public final int status;
public ExitException(int status) {
super("There is no escape!");
this.status = status;
}
}
private static class NoExitSecurityManager extends SecurityManager {
#Override
public void checkPermission(Permission perm) {
// allow anything.
}
#Override
public void checkPermission(Permission perm, Object context) {
// allow anything.
}
#Override
public void checkExit(int status) {
super.checkExit(status);
throw new ExitException(status);
}
}
private SecurityManager securityManager;
#Before
public void setUp() {
securityManager = System.getSecurityManager();
System.setSecurityManager(new NoExitSecurityManager());
}
#After
public void tearDown() {
System.setSecurityManager(securityManager);
}
Create a mock-able class that wraps System.exit()
I agree with EricSchaefer. But if you use a good mocking framework like Mockito a simple concrete class is enough, no need for an interface and two implementations.
Stopping test execution on System.exit()
Problem:
// do thing1
if(someCondition) {
System.exit(1);
}
// do thing2
System.exit(0)
A mocked Sytem.exit() will not terminate execution. This is bad if you want to test that thing2 is not executed.
Solution:
You should refactor this code as suggested by martin:
// do thing1
if(someCondition) {
return 1;
}
// do thing2
return 0;
And do System.exit(status) in the calling function. This forces you to have all your System.exit()s in one place in or near main(). This is cleaner than calling System.exit() deep inside your logic.
Code
Wrapper:
public class SystemExit {
public void exit(int status) {
System.exit(status);
}
}
Main:
public class Main {
private final SystemExit systemExit;
Main(SystemExit systemExit) {
this.systemExit = systemExit;
}
public static void main(String[] args) {
SystemExit aSystemExit = new SystemExit();
Main main = new Main(aSystemExit);
main.executeAndExit(args);
}
void executeAndExit(String[] args) {
int status = execute(args);
systemExit.exit(status);
}
private int execute(String[] args) {
System.out.println("First argument:");
if (args.length == 0) {
return 1;
}
System.out.println(args[0]);
return 0;
}
}
Test:
public class MainTest {
private Main main;
private SystemExit systemExit;
#Before
public void setUp() {
systemExit = mock(SystemExit.class);
main = new Main(systemExit);
}
#Test
public void executeCallsSystemExit() {
String[] emptyArgs = {};
// test
main.executeAndExit(emptyArgs);
verify(systemExit).exit(1);
}
}
System Stubs - https://github.com/webcompere/system-stubs - is also able to solve this problem. It shares System Lambda's syntax for wrapping around code that we know will execute System.exit, but that can lead to odd effects when other code unexpectedly exits.
Via the JUnit 5 plugin, we can provide insurance that any exit will be converted to an exception:
#ExtendWith(SystemStubsExtension.class)
class SystemExitUseCase {
// the presence of this in the test means System.exit becomes an exception
#SystemStub
private SystemExit systemExit;
#Test
void doSomethingThatAccidentallyCallsSystemExit() {
// this test would have stopped the JVM, now it ends in `AbortExecutionException`
// System.exit(1);
}
#Test
void canCatchSystemExit() {
assertThatThrownBy(() -> System.exit(1))
.isInstanceOf(AbortExecutionException.class);
assertThat(systemExit.getExitCode()).isEqualTo(1);
}
}
Alternatively, the assertion-like static method can also be used:
assertThat(catchSystemExit(() -> {
//the code under test
System.exit(123);
})).isEqualTo(123);
A quick look at the api, shows that System.exit can throw an exception esp. if a securitymanager forbids the shutdown of the vm. Maybe a solution would be to install such a manager.
You can use the java SecurityManager to prevent the current thread from shutting down the Java VM. The following code should do what you want:
SecurityManager securityManager = new SecurityManager() {
public void checkPermission(Permission permission) {
if ("exitVM".equals(permission.getName())) {
throw new SecurityException("System.exit attempted and blocked.");
}
}
};
System.setSecurityManager(securityManager);
You can test System.exit(..) with replacing Runtime instance.
E.g. with TestNG + Mockito:
public class ConsoleTest {
/** Original runtime. */
private Runtime originalRuntime;
/** Mocked runtime. */
private Runtime spyRuntime;
#BeforeMethod
public void setUp() {
originalRuntime = Runtime.getRuntime();
spyRuntime = spy(originalRuntime);
// Replace original runtime with a spy (via reflection).
Utils.setField(Runtime.class, "currentRuntime", spyRuntime);
}
#AfterMethod
public void tearDown() {
// Recover original runtime.
Utils.setField(Runtime.class, "currentRuntime", originalRuntime);
}
#Test
public void testSystemExit() {
// Or anything you want as an answer.
doNothing().when(spyRuntime).exit(anyInt());
System.exit(1);
verify(spyRuntime).exit(1);
}
}
There are environments where the returned exit code is used by the calling program (such as ERRORLEVEL in MS Batch). We have tests around the main methods that do this in our code, and our approach has been to use a similar SecurityManager override as used in other tests here.
Last night I put together a small JAR using Junit #Rule annotations to hide the security manager code, as well as add expectations based on the expected return code. http://code.google.com/p/junitsystemrules/
Most solutions will
terminate the test (method, not the entire run) the moment System.exit() is called
ignore an already installed SecurityManager
Sometimes be quite specific to a test framework
restrict to be used at max once per test case
Thus, most solutions are not suited for situations where:
Verification of side-effects are to be performed after the call to System.exit()
An existing security manager is part of the testing.
A different test framework is used.
You want to have multiple verifications in a single test case. This may be strictly not recommended, but can be very convenient at times, especially in combination with assertAll(), for example.
I was not happy with the restrictions imposed by the existing solutions presented in the other answers, and thus came up with something on my own.
The following class provides a method assertExits(int expectedStatus, Executable executable) which asserts that System.exit() is called with a specified status value, and the test can continue after it. It works the same way as JUnit 5 assertThrows. It also respects an existing security manager.
There is one remaining problem: When the code under test installs a new security manager which completely replaces the security manager set by the test. All other SecurityManager-based solutions known to me suffer the same problem.
import java.security.Permission;
import static java.lang.System.getSecurityManager;
import static java.lang.System.setSecurityManager;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.fail;
public enum ExitAssertions {
;
public static <E extends Throwable> void assertExits(final int expectedStatus, final ThrowingExecutable<E> executable) throws E {
final SecurityManager originalSecurityManager = getSecurityManager();
setSecurityManager(new SecurityManager() {
#Override
public void checkPermission(final Permission perm) {
if (originalSecurityManager != null)
originalSecurityManager.checkPermission(perm);
}
#Override
public void checkPermission(final Permission perm, final Object context) {
if (originalSecurityManager != null)
originalSecurityManager.checkPermission(perm, context);
}
#Override
public void checkExit(final int status) {
super.checkExit(status);
throw new ExitException(status);
}
});
try {
executable.run();
fail("Expected System.exit(" + expectedStatus + ") to be called, but it wasn't called.");
} catch (final ExitException e) {
assertEquals(expectedStatus, e.status, "Wrong System.exit() status.");
} finally {
setSecurityManager(originalSecurityManager);
}
}
public interface ThrowingExecutable<E extends Throwable> {
void run() throws E;
}
private static class ExitException extends SecurityException {
final int status;
private ExitException(final int status) {
this.status = status;
}
}
}
You can use the class like this:
#Test
void example() {
assertExits(0, () -> System.exit(0)); // succeeds
assertExits(1, () -> System.exit(1)); // succeeds
assertExits(2, () -> System.exit(1)); // fails
}
The code can easily be ported to JUnit 4, TestNG, or any other framework, if necessary. The only framework-specific element is failing the test. This can easily be changed to something framework-independent (other than a Junit 4 Rule
There is room for improvement, for example, overloading assertExits() with customizable messages.
Use Runtime.exec(String command) to start JVM in a separate process.
There is a minor problem with the SecurityManager solution. Some methods, such as JFrame.exitOnClose, also call SecurityManager.checkExit. In my application, I didn't want that call to fail, so I used
Class[] stack = getClassContext();
if (stack[1] != JFrame.class && !okToExit) throw new ExitException();
super.checkExit(status);
A generally useful approach that can be used for unit and integration testing, is to have a package private (default access) mockable runner class that provides run() and exit() methods. These methods can be overridden by Mock or Fake test classes in the test modules.
The test class (JUnit or other) provides exceptions that the exit() method can throw in place of System.exit().
package mainmocked;
class MainRunner {
void run(final String[] args) {
new MainMocked().run(args);
}
void exit(final int status) {
System.exit(status);
}
}
the class with main() below, also has an altMain() to receive the mock or fake runner, when unit or integration testing:
package mainmocked;
public class MainMocked {
private static MainRunner runner = new MainRunner();
static void altMain(final String[] args, final MainRunner inRunner) {
runner = inRunner;
main(args);
}
public static void main(String[] args) {
try {
runner.run(args);
} catch (Throwable ex) {
// Log("error: ", ex);
runner.exit(1);
}
runner.exit(0);
} // main
public void run(String[] args) {
// do things ...
}
} // class
A simple mock (with Mockito) would be:
#Test
public void testAltMain() {
String[] args0 = {};
MainRunner mockRunner = mock(MainRunner.class);
MainMocked.altMain(args0, mockRunner);
verify(mockRunner).run(args0);
verify(mockRunner).exit(0);
}
A more complex test class would use a Fake, in which run() could do anything, and an Exception class to replace System.exit():
private class FakeRunnerRuns extends MainRunner {
#Override
void run(String[] args){
new MainMocked().run(args);
}
#Override
void exit(final int status) {
if (status == 0) {
throw new MyMockExitExceptionOK("exit(0) success");
}
else {
throw new MyMockExitExceptionFail("Unexpected Exception");
} // ok
} // exit
} // class
Another technique here is to introduce additional code into the (hopefully small number of) places where the logic does the System.exit(). This additional code then avoids doing the System.exit() when the logic is being called as part of unit test. For example, define a package private constant like TEST_MODE which is normally false. Then have the unit test code set this true and add logic to the code under test to check for that case and bypass the System.exit call and instead throw an exception that the unit test logic can catch. By the way, in 2021 and using something like spotbugs, this problem can manifest itself in the obscure error that "java.io.IOException: An existing connection was forcibly closed by the remote host".
Calling System.exit() is a bad practice, unless it's done inside a main(). These methods should be throwing an exception which, ultimately, is caught by your main(), who then calls System.exit with the appropriate code.