Following is the actor, I've defined (trying to get my head around persistent actor!!)
public class Country : ReceivePersistentActor
{
public override string PersistenceId => GetType().Name + state.Id;
private CountryState state;
public Country()
{
Command<CreateCountry>(CreateCountry);
}
private bool CreateCountry(CreateCountry cmd)
{
Persist(new CountryCeated
{
Id = cmd.Id,
Code = cmd.Code,
Description = cmd.Description,
Active = cmd.Active
}, evt =>
{
state = new CountryState
{
Id = evt.Id,
Code = evt.Code,
Description = evt.Description,
Active = evt.Active
};
});
return true;
}
}
Following is unit test case that I've defined:
[TestClass]
public class CountrySpec : TestKit
{
[TestMethod]
public void CountryActor_Should_Create_A_Country()
{
var country = Sys.ActorOf(Props.Create(() => new Country()), "Country");
country.Tell(new CreateCountry(Guid.NewGuid(), "UK", "United Kingdom", true));
ExpectNoMsg();
}
}
When I run the test case, there is an exception that I can see in the output window of the test case
[ERROR][25/08/2016 08:25:07][Thread 0007][akka://test/user/Country] Object reference not set to an instance of an object.
Cause: [akka://test/user/Country#552449332]: Akka.Actor.ActorInitializationException: Exception during creation ---> System.NullReferenceException: Object reference not set to an instance of an object.
at Domain.Country.get_PersistenceId() in Y:\Spikes\StatefulActors\Domain\Country.cs:line 9
at Akka.Persistence.Eventsourced.StartRecovery(Recovery recovery)
at Akka.Persistence.Eventsourced.AroundPreStart()
at Akka.Actor.ActorCell.<>c__DisplayClass154_0.<Create>b__0()
at Akka.Actor.ActorCell.UseThreadContext(Action action)
at Akka.Actor.ActorCell.Create(Exception failure)
--- End of inner exception stack trace ---
at Akka.Actor.ActorCell.Create(Exception failure)
at Akka.Actor.ActorCell.SysMsgInvokeAll(EarliestFirstSystemMessageList messages, Int32 currentState)
but the test case is marked as success
Is there any way/settings in the TestKit, where it can be set such that for any exception, mark the test case failed?
By default, any exceptions inside actors are encapsulated - that means they don't bubble up, blowing the rest of the system.
Actors come in systems, and can be tested by observing the way they communicate with each other. Usually it comes up to providing inputs and asserting outputs from actor system - in your case test has passed, since you haven't validated any output. From the perspective of your test, this actor could be dead and it wouldn't make a difference.
Validating an outputs (either by assertion inside actor itself or i.e. using a custom test journal) is the best way to work with tests.
If for some reason you still have to catch exceptions inside actors, you could create supervision strategy bound to i.e. TestActor, where all exceptions could be forwarded:
public class TestingStrategy : OneForOneStrategy
{
protected TestingStrategy(IActorRef probe) : base(exception =>
{
probe.Tell(exception);
return DefaultDecider.Decide(exception);
}) { }
}
Related
When I try to run my Junit tests (Wrote in Kotlin) I get the following exception :
java.lang.IllegalArgumentException: Attempted to find dependent attachment for class javax/xml/bind/DatatypeConverter, but could not find a suitable candidate.
I tried to comment/decomment some lines in following code, it seems that the exception occurs when I call command()
class IRIssueTests {
class DummyCommand : TypeOnlyCommandData()
private val ledgerServices = MockServices(listOf("com.my.package.name"))
private val ALICE = TestIdentity(CordaX500Name(organisation = "Alice", locality = "TestLand", country = "US"))
#Test
fun mustIncludeIssueCommand() {
val ir = IRState(
UniqueIdentifier(),
mutableListOf(ALICE.party)
)
ledgerServices.ledger {
transaction {
output(IRContract.ID, ir)
command(listOf(ALICE.publicKey), DummyCommand())
fails()
}
transaction {
output(IRContract.ID, ir)
command(listOf(ALICE.publicKey), IRContract.Commands.Issue())
verifies()
}
}
}
}
I would like to understand why I'm getting this exception and how to resolve it to make my test passing
Kotlin tests must be run with JDK8.
Change configuration of JDK8 in your project before running tests.
This will avoid this exception
New to Akka. Creating a new Scala class that extends SupervisorStrategy gives me the following template to work with:
class MySupervisorStrategy extends SupervisorStrategy {
override def decider: Decider = ???
override def handleChildTerminated(context: ActorContext, child: ActorRef,
children: Iterable[ActorRef]): Unit = ???
override def processFailure(context: ActorContext, restart: Boolean,
child: ActorRef, cause: Throwable, stats: ChildRestartStats, children: Iterable[ChildRestartStats]): Unit = ???
}
I'm looking for a way to access:
The Throwable/Exception that was thrown from the child actor
The child actor ActorRef that threw the exception
The message that was passed to the child actor that prompted the exception to be thrown
I think the Decider (which is actually a PartialFunction[Throwable,Directive]) gets passed the Throwable whenever the child throws the exception, but I'm not seeing where I could get access to #2 and #3 from my list above. Any ideas?
Update
From the posted fiddle, it looks like a valid Decider is:
{
case ActorException(ref,t,"stop") =>
println(s"Received 'stop' from ${ref}")
Stop
case ActorException(ref,t,"restart") =>
println(s"Received 'restart' from ${ref}")
Restart
case ActorException(ref,t,"resume") =>
println(s"Received 'resume' from ${ref}")
Resume
}
Above, I see all three:
The exception that was thrown by the child
The child (ref) that threw the exception
The message that was sent to the child originally (that caused the exception to be thrown)
It looks like there's nothing in that Decider that needs to be defined inside that Supervisor class. I'd like to pull the Decider logic out into, say, MyDecider.scala and find a way to refactor the Supervisor so that its supervisorStrategy uses an instance of MyDecider, so maybe something similar to:
class Supervisor extends Actor {
import akka.actor.OneForOneStrategy
import akka.actor.SupervisorStrategy._
import scala.concurrent.duration._
var child: ActorRef = _
override val supervisorStrategy =
OneForOneStrategy(maxNrOfRetries = 10, withinTimeRange = 1 minute, decider = myDecider)
...
}
For #2 you could access the sender "if the strategy is declared inside the supervising actor"
If the strategy is declared inside the supervising actor (as opposed to within a companion object) its decider has access to all internal state of the actor in a thread-safe fashion, including obtaining a reference to the currently failed child (available as the sender of the failure message).
The message is not made available so the only option is to catch your exception and throw a custom one with the message that was received.
Here is a quick fiddle
class ActorSO extends Actor {
def _receive: Receive = {
case e =>
println(e)
throw new RuntimeException(e.toString)
}
final def receive = {
case any => try {
_receive(any)
}
catch {
case t:Throwable => throw new ActorException(self,t,any)
}
}
}
Update
A Decider is just a PartialFunction so you can pass it in the constructor.
object SupervisorActor {
def props(decider: Decider) = Props(new SupervisorActor(decider))
}
class SupervisorActor(decider: Decider) extends Actor {
override val supervisorStrategy = OneForOneStrategy()(decider)
override def receive: Receive = ???
}
class MyDecider extends Decider {
override def isDefinedAt(x: Throwable): Boolean = true
override def apply(v1: Throwable): SupervisorStrategy.Directive = {
case t:ActorException => Restart
case notmatched => SupervisorStrategy.defaultDecider.apply(notmatched)
}
}
object Test {
val myDecider: Decider = {
case t:ActorException => Restart
case notmatched => SupervisorStrategy.defaultDecider.apply(notmatched)
}
val myDecider2 = new MyDecider()
val system = ActorSystem("stackoverflow")
val supervisor = system.actorOf(SupervisorActor.props(myDecider))
val supervisor2 = system.actorOf(SupervisorActor.props(myDecider2))
}
By doing so, you won't be able to access supervisor state like the ActorRef of the child that throw the exception via sender() (although we are including this in the ActorException)
Regarding your original question of accessing from the supervisor the child message that cause the exception, you can see here (from akka 2.5.3) that the akka developers choose to not make it available for decision.
final protected def handleFailure(f: Failed): Unit = {
// ¡¡¡ currentMessage.message is the one that cause the exception !!!
currentMessage = Envelope(f, f.child, system)
getChildByRef(f.child) match {
/*
* only act upon the failure, if it comes from a currently known child;
* the UID protects against reception of a Failed from a child which was
* killed in preRestart and re-created in postRestart
*/
case Some(stats) if stats.uid == f.uid ⇒
// ¡¡¡ currentMessage.message is not passed to the handleFailure !!!
if (!actor.supervisorStrategy.handleFailure(this, f.child, f.cause, stats, getAllChildStats)) throw f.cause
case Some(stats) ⇒
publish(Debug(self.path.toString, clazz(actor),
"dropping Failed(" + f.cause + ") from old child " + f.child + " (uid=" + stats.uid + " != " + f.uid + ")"))
case None ⇒
publish(Debug(self.path.toString, clazz(actor), "dropping Failed(" + f.cause + ") from unknown child " + f.child))
}
}
I am trying to implement the following use case as part of my akka learning
I would like to calculate the total streets in all cities of all states. I have a database that contain the details needed. Here is what i have so far
Configuration
akka.actor.deployment {
/CityActor{
router = random-pool
nr-of-instances = 10
}
/StateActor {
router = random-pool
nr-of-instances = 1
}}
Main
public static void main(String[] args) {
try {
Config conf = ConfigFactory
.parseReader(
new FileReader(ClassLoader.getSystemResource("config/forum.conf").getFile()))
.withFallback(ConfigFactory.load());
System.out.println(conf);
final ActorSystem system = ActorSystem.create("AkkaApp", conf);
final ActorRef masterActor = system.actorOf(Props.create(MasterActor.class), "Migrate");
masterActor.tell("", ActorRef.noSender());
} catch (Exception e) {
e.printStackTrace();
}
}
MasterActor
public class MasterActor extends UntypedActor {
private final ActorRef randomRouter = getContext().system()
.actorOf(Props.create(StateActor.class).withRouter(new akka.routing.FromConfig()), "StateActor");
#Override
public void onReceive(Object message) throws Exception {
if (message instanceof String) {
getContext().watch(randomRouter);
for (String aState : getStates()) {
randomRouter.tell(aState, getSelf());
}
randomRouter.tell(new Broadcast(PoisonPill.getInstance()), getSelf());
} else if (message instanceof Terminated) {
Terminated ater = (Terminated) message;
if (ater.getActor().equals(randomRouter)) {
getContext().system().terminate();
}
}
}
public List<String> getStates() {
return new ArrayList<String>(Arrays.asList("CA", "MA", "TA", "NJ", "NY"));
};}
StateActor
public class StateActor extends UntypedActor {
private final ActorRef randomRouter = getContext().system()
.actorOf(Props.create(CityActor.class).withRouter(new akka.routing.FromConfig()), "CityActor");
#Override
public void onReceive(Object message) throws Exception {
if (message instanceof String) {
System.out.println("Processing state " + message);
for (String aCity : getCitiesForState((String) message)) {
randomRouter.tell(aCity, getSelf());
}
Thread.sleep(1000);
}
}
public List<String> getCitiesForState(String stateName) {
return new ArrayList<String>(Arrays.asList("Springfield-" + stateName, "Salem-" + stateName,
"Franklin-" + stateName, "Clinton-" + stateName, "Georgetown-" + stateName));
};}
CityActor
public class CityActor extends UntypedActor {
#Override
public void onReceive(Object message) throws Exception {
if (message instanceof String) {
System.out.println("Processing city " + message);
Thread.sleep(1000);
}
}}
Did i implement this use case properly?
I cannot get the code to terminate properly, i get dead letters messages. I know why i am getting them, but not sure how to properly implement it.
Any help is greatly appreciated.
Thanks
I tested and ran your use case with Akka 2.4.17. It works and terminate properly, without any dead letters logged.
Here are some remarks/suggestions to improve your understanding of the Akka toolkit:
Do not use Thread.sleep() inside an actor. Basically, it is never a good practice since a same thread may do many tasks for many actors (this is the default behavior with a shared thread pool). Instead, you can use an Akka scheduler or assign a single thread to a specific Actor (see this post for more details). See also the Akka documentation about that topic.
Having some dead letters is not always an issue. It generally arises when the system stops an Actor that had some messages within its mailbox. In this case, the remaining unprocessed messages are sent to deadLetters of the ActorSystem. I recommend you to check the configuration you provided for the logging of dead letters. If the file forum.conf you provided is your complete configuration file for Akka, you may want to customize some additional settings. See the page Logging of Dead Letters and Stopping actors on Akka's website. For instance, you could have a section like this:
akka {
# instead of System.out.println(conf);
log-config-on-start = on
# Max number of dead letters to log
log-dead-letters = 10
log-dead-letters-during-shutdown = on
}
Instead of using System.out.println() to log/debug, it is more convenient to set up a dedicated logger for each Actor that provides you additional information such as dispatchers, Actor name, etc. If your are interested, have a look to the Logging page.
Use some custom immutable message objects instead of systematic Strings. At first, it may seem painful to have to declare new additional classes but in the end it helps to better design complex behaviors and it's more readable. For instance, an actor A can answer to a RequestMsg coming from an actor B with an AnswerMsg or a custom ErrorMsg. Then, for your actor B, you will end up with the following onReceive() method:
#Override
public void onReceive(Object message) {
if (message instanceof AnswerMsg) {
// OK
AnswerMsg answerMsg = (AnswerMsg) message;
// ...
}
if (message instanceof ErrorMsg) {
// Not OK
ErrorMsg errorMsg = (ErrorMsg) message;
// ...
}
else {
// Unexpected behaviour, log it
log.error("Error, received " + message.toString() + " object.")
}
}
I hope that these resources will be useful for you.
Have a happy Akka programming! ;)
Consider the following, where I am testing that an injected dependency's method is called a specific number of times:
[Fact]
public void WhenBossTalksEmployeeBlinksTwice()
{
// arrange
var employee = new Mock<IEmployee>();
employee.Setup(e => e.Blink());
var boss = new Boss(employee.Object);
// act
boss.Talk();
// assert
employee.Verify(e => e.Blink(), Times.Exactly(2)); // Passes as expected
employee.Verify(e => e.Blink(), Times.Exactly(1)); // Fails as expected
}
When I force the failing test, the output is:
Moq.MockException: Invocation was not performed on the mock 1 times: e
=> e.Blink()
What would be better is something like:
Moq.MockException: Invocation was unexpectedly performed 2 times, not 1 time: e
=> e.Blink()
Here are the items involved with the test:
public interface IEmployee { void Blink(); }
public class Boss {
private readonly IEmployee _employee;
public Boss(IEmployee employee) { _employee = employee; }
public void Talk() {
_employee.Blink();
_employee.Blink();
}
}
Is it possible to harvest and display the actual number of times the dependency's method was called, in the failing test's error message?
I'm not sure that it matters, but I'm using Moq v3.1.416.3 (not the latest, I know, but another library I'm using hasn't updated to Moq 4.x yet…)
I don't know of a straight way to harvest the information in Moq3.
What I would do is use a callback on the setup of Blink.
int count = 0;
employee.Setup(e => e.Blink()).Callback(() => count++);
...
employee.Verify(e => e.Blink(), Times.Exactly(1), "Moq.MockException: Invocation was unexpectedly performed " + count + " times, not 1 time: e => e.Blink()"); // Fails as expected
How do I set up my test method on that mocks a repository which accepts an object?
This is what I have so far:
Service.cs
public int AddCountry(string countryName)
{
Country country = new Country();
country.CountryName = countryName;
return geographicsRepository.SaveCountry(country).CountryId;
}
test.cs
[Test]
public void Insert_Country()
{
//Setup
var geographicsRepository = new Mock<IGeographicRepository>();
geographicsRepository.Setup(x => x.SaveCountry(It.Is<Country>(c => c.CountryName == "Jamaica"))); //How do I return a 1 here?
GeographicService geoService = new GeographicService(geographicsRepository.Object);
int id = geoService.AddCountry("Jamaica");
Assert.AreEqual(1, id);
}
SaveCountry(Country country); returns an int.
I need to do 2 things:
First test, I need to tell the setup to return an int of 1.
I need to create a second test Insert_Duplicate_Country_Throws_Exception(). In my Setup, how do I tell the repository to throw an error when I do:
int id = geoService.AddCountry("Jamaica");
int id = geoService.AddCountry("Jamaica");
Framework:
NUnit.
Moq.
ASP.NET MVC - repository pattern.
Your first test should look something like this:
[Test]
public void Insert_Country()
{
Mock<IGeographicRepository> geographicsRepository = new Mock<IGeographicRepository>();
GeographicService geoService = new GeographicService(geographicsRepository.Object);
// Setup Mock
geographicsRepository
.Setup(x => x.SaveCountry(It.IsAny<Country>()))
.Returns(1);
var id = geoService.AddCountry("Jamaica");
Assert.IsInstanceOf<Int32>(id);
Assert.AreEqual(1, id);
geographicsRepository.VerifyAll();
}
The second test should look like this:
[Test]
public void Insert_Duplicate_Country_Throws_Exception()
{
Mock<IGeographicRepository> geographicsRepository = new Mock<IGeographicRepository>();
GeographicService geoService = new GeographicService(geographicsRepository.Object);
// Setup Mock
geographicsRepository
.Setup(x => x.SaveCountry(It.IsAny<Country>()))
.Throws(new MyException());
try
{
var id = geoService.AddCountry("Jamaica");
Assert.Fail("Exception not thrown");
}
catch (MyException)
{
geographicsRepository.VerifyAll();
}
}
I think maybe you are slightly misunderstanding the purpose of testing with mocks in the two scenarios you have supplied.
In the first scenario, you wish to test that 1 is returned when you pass in "Jamaica". This is not a mock test case but a test case for real behaviour as you wish to test a specific input against an expected output i.e. "Jamaica" -> 1. In this situation mocking is more useful to ensure that internally your service calls SaveCountry on the repository with the expected country, and that it returns the value from the call.
Setting up your "SaveCountry" case and then calling "VerifyAll" on your mock is the key. This will assert that "SaveCountry" was indeed called with country "Jamaica", and that the expected value is returned. In this way you have confidence that your service is wired up to your repository as expected.
[Test]
public void adding_country_saves_country()
{
const int ExpectedCountryId = 666;
var mockRepository = new Mock<IGeographicRepository>();
mockRepository.
Setup(x => x.SaveCountry(It.Is<Country>(c => c.CountryName == "Jamaica"))).
Returns(ExpectedCountryId);
GeographicService service= new GeographicService(mockRepository.Object);
int id = service.AddCountry(new Country("Jamaica"));
mockRepo.VerifyAll();
Assert.AreEqual(ExpectedCountryId, id, "Expected country id.");
}
In the second scenario you wish to test that an exception is raised when you attempt to add a duplicate country. There's not much point in doing this with a mock as all you will test is that your mock has behaviour when adding duplicates, not your real implementation.