Develop Reference

Running gRPC server and client in JUnit test (sometimes) leads to a deadlock

Often when I consider a new library or technology, I create a small POC or test program to get a feel for it. So I did with gRPC-Spring-Boot-Starter. A simple example code is posted below my question text.
This sample has been extended in complexity and eventually, the library has found its way into production code. So far it has survived many runs under moderate load.
Note that, naturally, the production service is not client to itself. But the production gRPC service is in fact client to other gRPC services.
Now I was thinking to write some kind of between-unit-and-integration test where I spin up local instances (starting with a single one) of those other gRPC services (pulling data from some static local resource, for example). Basically, this test code looks very much like the one posted below my question.
However - as soon as we poll for results in forEachRemaining(), the test ends up hanging: I suspect a deadlock in ClientCalls#waitAndDrain (io.grpc:grpc-stub).
The funny thing is - this does not happen if the client were created "manually", i.e. without utilizing the third-party Spring extension:
ManagedChannel channel = ManagedChannelBuilder.forTarget("localhost:9091")
.defaultLoadBalancingPolicy("round_robin")
.usePlaintext()
.build();
StockStaticDataRequestServiceBlockingStub stub = StockStaticDataRequestServiceGrpc.newBlockingStub(channel);
I use Spring Boot 2.6.3, gRPC-Spring-Boot-Starter 2.13.1, gRPC 1.44.0, proto 3.19.2 and netty 4.1.73, for what it is worth.
Now I wonder if someone here encountered similar issues or can give me some pointers while I am trying to figure out the inner workings of gRPC more.
Added sample project on GH.
The main branch contains the - maybe dubious - test setup I chose in the beginning, branches are some refinements, like using #Abhijit Sarkar's grpc-test library. Tests are green so far.
grpc:
client:
stocks:
address: 'static://localhost:9091'
enableKeepAlive: false
negotiationType: plaintext
server:
port: 9092
#SpringBootTest
class TestGrpc {
#GrpcClient("stocks")
private StockStaticDataRequestServiceBlockingStub stub;
#BeforeAll
public static void setUp() throws Exception {
final Server server = ServerBuilder
.forPort(9091)
.addService(new StockStaticDataRequestTestService())
.build();
server.start();
final Thread serverThread = new Thread(() -> {
try {
server.awaitTermination();
} catch (final InterruptedException e) {
Thread.currentThread().interrupt();
}
});
serverThread.setDaemon(false);
serverThread.start();
}
#Test
void testClient() {
StockStaticManyDataRequest request = StockStaticManyDataRequest.newBuilder()
.addAllTickerSymbols(List.of("AAPL"))
.build();
stub.getManyStockStatics(request).forEachRemaining(security -> {
LOG.info("security={}", security);
});
}
}
public class StockStaticDataRequestTestService extends StockStaticDataRequestServiceImplBase {
#Override
public void getManyStockStatics(StockStaticManyDataRequest request, StreamObserver<Security> responseObserver) {
responseObserver.onNext(Security.newBuilder()
.setSecurity("TEST-MANY")
.build());
responseObserver.onNext(Security.newBuilder()
.setSecurity("TEST-MORE")
.build());
responseObserver.onCompleted();
}
}
message Security {
string tickerSymbol = 1;
string security = 2;
}
message StockStaticManyDataRequest {
repeated string tickerSymbols = 1;
}
service StockStaticDataRequestService {
rpc getManyStockStatics(StockStaticManyDataRequest) returns (stream Security) {}
}

I think what the problem might be is that you should not be starting the server at all. There are some grpc-spring-boot-starter annotations that should be added to a test configuration class that will start / stop the server. See details here.
https://yidongnan.github.io/grpc-spring-boot-starter/en/server/testing.html#integration-tests
I also tried to make what you have work, but the server once started really won't shutdown. This makes the next test suite that runs fail due to port conflicts when it tries to start.
Here's my test class.
#Slf4j
#SpringBootTest
#ActiveProfiles("test")
#SpringJUnitConfig(classes = { ServiceIntegrationTestConfiguration.class })
#DirtiesContext
class TestGprc {
#GrpcClient("stocks")
private StockStaticDataRequestServiceBlockingStub stub;
/**
* #throws java.lang.Exception
*/
#BeforeAll
static void setUpBeforeClass() throws Exception {
log.info("setUpBeforeClass");
}
/**
* #throws java.lang.Exception
*/
#AfterAll
static void tearDownAfterClass() throws Exception {
log.info("tearDownAfterClass");
}
/**
* #throws java.lang.Exception
*/
#BeforeEach
void setUp() throws Exception {
}
/**
* #throws java.lang.Exception
*/
#AfterEach
void tearDown() throws Exception {
}
#Test
#DirtiesContext
void testClient() {
StockStaticManyDataRequest request = StockStaticManyDataRequest.newBuilder()
.addAllTickerSymbols(List.of("AAPL"))
.build();
stub.getManyStockStatics(request).forEachRemaining(security -> {
log.info("security={}", security);
});
}
}
Here's the configuration project.
#Configuration
#ImportAutoConfiguration({ GrpcServerAutoConfiguration.class, // Create required server beans
GrpcServerFactoryAutoConfiguration.class, // Select server implementation
GrpcClientAutoConfiguration.class,
GrpcStarterApplication.class})
public class ServiceIntegrationTestConfiguration {
// add mock beans here of needed.
}
My overrides for the properties. see application-test.yaml
grpc:
client:
stocks:
address: in-process:test
enableKeepAlive:
negotiationType:
server:
inProcessName: test
port: -1
I posted the entire maven project here:
https://github.com/aerobiotic/grpc-spring-starter
Simply clone it and mvn clean install :-)
As far as your dead-lock goes in your production code:
make sure you are calling onCompleted
check your catch blocks and make sure onError is being called and that there is logging happening.
It's possible that starting the server and not getting it shutdown is affecting something. Perhaps test code is connecting to a server from a previous test.

How can i unit test a method that contains vertx().eventBus().send()?

Frustrating. Everywhere i look, i see samples of testing async Vertx code, but nothing that comes close to what i am trying to test.
Vertx 3.3.2, JUnit 4.12, Java 8
The method under test sends a message to the event bus. I want to verify that what happens in the eventBus().send() response handler is happening.
Sooooooo many examples i see have the eventBus().send() method in the TEST ITSELF (thus, testing the other end of the event bus - the consumer) I want to test the response handler in the .send()
I have tried Async in the test. Tried ArgumentCaptor. Tried Thread.sleep(). Tried doAnswer(). Nothing seems to get the test to (a) wait for the async eventBus().send() call in the method under test to finish and (b) able to verify() that there was an interaction (i think this might have to do with the different between the Vertx.TestContext and the JUnit.Runner Context..)
Code:
Method under test:
public void sendToEventBusAddress(RoutingContext context, String requestId, String userId) {
List<String> stuff = split(context.request().getParam("stuffToSplit"));
JsonObject eventBusMessage = new JsonObject()
.put("requestId", requestId)
.put("stuffList", new JsonArray(stuff))
.put("userId", userId);
LOGGER.info("Putting message: {} onto the EventBus at address: {}", eventBusMessage.encodePrettily(), EventBusEndpointEnum.STUFF_ACCESS.getValue());
context.vertx().eventBus().send(EventBusEndpointEnum.STUFF_ACCESS.getValue(), eventBusMessage, new DeliveryOptions().setSendTimeout(timeout), async -> {
if (async.succeeded()) {
LOGGER.info("EventBus Response: {}", async.result().body().toString());
context.response().setStatusCode(HttpStatus.SC_OK);
context.response().headers().set(HttpHeaders.CONTENT_TYPE, MediaType.TEXT_PLAIN);
context.response().end(async.result().body().toString());
} else {
LOGGER.error(errorMessage);
context.response().setStatusCode(HttpStatus.SC_BAD_REQUEST);
context.response().end(errorMessage);
}
});
}
Simplified (non-working) Test case and class:
#RunWith(VertxUnitRunner.class)
public class MyBrokenTest {
#Mock private RoutingContext routingContext;
#Mock private HttpServerRequest contextRequest;
#Mock private HttpServerResponse contextResponse;
#Mock private MultiMap responseHeaders;
#Rule public RunTestOnContext rule = new RunTestOnContext();
#Before
public void setUp(TestContext context) {
MockitoAnnotations.initMocks(this);
}
#Test
public void testOne(TestContext context) {
when(routingContext.vertx()).thenReturn(rule.vertx());
when(routingContext.request()).thenReturn(contextRequest);
when(contextRequest.getParam("stuffToSplit")).thenReturn("04MA");
when(routingContext.response()).thenReturn(contextResponse);
when(contextResponse.headers()).thenReturn(responseHeaders);
rule.vertx().eventBus().consumer(EventBusEndpointEnum.STUFF_ACCESS.getValue(), res -> {
res.reply("yo");
});
ClassUnderTest cut= new ClassUnderTest(180000);
cut.sendToEventBusAddress(routingContext, "testRequestId", "UnitTestId");
verify(contextResponse).setStatusCode(200);
}
}
I know that the test in its current form won't work, because the method under test returns as soon as the eventBus().send() method is called inside the method, and therefore, the verify fails with 'no interactions'.
What i can't figure out, is how to verify it properly given the async nature of Vertx!
Thanks

I did it so:
At #BeforeAll annotated method I deploy only the sending verticle.
At #BeforeEach - I create a consumer for the given message and store message(s) to variable/collection
Something like:
receivedMessage = new Message[1];
eventBus.consumer("DB",
message -> {
message.reply("OK");
receivedMessage[0] = message;
});
context.completeNow();
In test I validate stored value(s):
client.get(8080, "localhost", "/user/" + id)
.as(BodyCodec.string())
.send(context.succeeding((response -> context.verify(() -> {
Assertions.assertEquals(expectedMessage, receivedMessage[0].body());
context.completeNow();
}))));

Unit testing a Restlet extractor

I'm looking for some guidance on real unit testing for Restlet components, and specifically extractors. There is plenty of advice on running JUnit to rest entire endpoints, but being picky this is not unit testing, but integration testing. I really don't want to have set up an entire routing system and Spring just to check an extractor against a mock data repository.
The extractor looks like this:
public class CaseQueryExtractor extends Extractor {
protected int beforeHandle(Request request, Response response) {
extractFromQuery("offset", "offset", true);
extractFromQuery("limit", "limit", true);
// Stuff happens...
attributes.put("query", query);
return CONTINUE;
}
}
I'm thinking part of the virtue of Restlets is that its nice routing model ought to make unit testing easy, but I can't figure out what I need to do to actually exercise extractFromQuery and its friends, and all my logic that builds a query object, without mocking so much that I'm losing testing against a realistic web request.
And yes, I am using Spring, but I don't want to have to set the whole context for this -- I'm not integration testing as I haven't actually finished the app yet. I'm happy to inject manually, once I know what I need to make to get this method called.
Here's where I'm at now:
public class CaseQueryExtractorTest {
private class TraceRestlet extends Restlet {
// Does snothing, but prevents warning shouts
}
private CaseQueryExtractor extractor;
#Before
public void initialize() {
Restlet mock = new TraceRestlet();
extractor = new CaseQueryExtractor();
extractor.setNext(mock);
}
#Test
public void testBasicExtraction() {
Reference reference = new Reference();
reference.addQueryParameter("offset", "5");
reference.addQueryParameter("limit", "3");
Request request = new Request(Method.GET, reference);
Response response = extractor.handle(request);
extractor.handle(request, response);
CaseQuery query = (CaseQuery) request.getAttributes().get("query");
assertNotNull(query);
}
}
Which of course fails, as whatever set up I am doing isn't enough to make Restlets able to extract the query parameters.
Any thoughts or pointers?

There is a test module in Restlet that can provide you some hints about unit testing. See https://github.com/restlet/restlet-framework-java/tree/master/modules/org.restlet.test/src/org/restlet/test.
You can have a look at class HeaderTestCase (see https://github.com/restlet/restlet-framework-java/blob/master/modules/org.restlet.test/src/org/restlet/test/HeaderTestCase.java).
For information, if you use attributes from request, your unit test will pass ;-) See below:
public class CaseQueryExtractor extends Extractor {
protected int beforeHandle(Request request, Response response) {
extractFromQuery("offset", "offset", true);
extractFromQuery("limit", "limit", true);
// Stuff happens...
CaseQuery query = new CaseQuery();
Map<String,Object> attributes = request.getAttributes();
attributes.put("query", query);
return CONTINUE;
}
}
I don't know if you want to go further...
Hope it helps you,
Thierry

MockWebServer's takeRequest() method takes long to response or hangs

I'm using MockWebServer library in my Android JUnit tests. I'm testing an SDK that makes calls to a server. So I'm using MockWebServer to override these server URLs and capture what the SDK is sending to make assertions on it.
The problem that I'm running into is that if I try to do server.takeRequest() and assign it to a new RecordedRequest variable, the test hangs up on the second server.takeRequest() and sometimes, even on the first one -- if I run it on an emulator it hangs on the first server.takeRequest() method but if I run it on my physical Android device, it freezes on the second server.takeRequest() method.
public void testSomething() {
final MockWebServer server = new MockWebServer();
try {
server.play();
server.enqueue(new MockResponse().setBody("")
.setResponseCode(HttpURLConnection.HTTP_INTERNAL_ERROR));
server.enqueue(new MockResponse().setBody("")
.setResponseCode(HttpURLConnection.HTTP_OK));
server.enqueue(new MockResponse().setBody("")
.setResponseCode(HttpURLConnection.HTTP_OK));
URL url = server.getUrl("/");
// This internal method overrides some of the hardcoded URLs
// within the SDK that I'm testing.
Util.overrideUrls(url.toString())
// Do some server calls via the SDK utilizing the mock server url.
RecordedRequest requestFor500 = server.takeRequest();
// Do some assertions with 'requestFor500'
// Do some more server calls via the SDK utilizing the mock server url.
/*
* This is the part where the JUnit test hangs or seems to go into
* an infinite loop and never recovers
*/
RecordedRequest requestAfter500Before200 = server.takeRequest();
} catch {
...
}
}
Am I doing something wrong or is this some type of bug with MockWebServer?

Add timeout to MockWebServer so that it does not hang
server.takeRequest(1, TimeUnit.SECONDS);

There seems to be a problem with MockWebServer's dispatch queue, which freezes for some reason when serving responses which are not 200 or 302. I have solved this by providing a custom dispatcher:
MockWebServer server = ...;
final MockResponse response = new MockResponse().setResponseCode(401);
server.setDispatcher(new Dispatcher() {
#Override
public MockResponse dispatch(RecordedRequest request)
throws InterruptedException {
return response; // this could have been more sophisticated
}
});
Tested with MockWebServer 2.0.0

PlayFramework - Running functional test with json rendering

I'm trying to run this functional test
public class JsonRenderTest extends FunctionalTest {
#Before
public void setup() {
Fixtures.deleteDatabase();
Fixtures.loadModels("data.yml");
}
#Test
public void testThatJsonRenderingWorks() {
Response response = GET("/recipe/1");
assertIsOk(response);
}
}
The action answering this call is this
public static void showRecipe(Long id){
Recipe recipe = Recipe.findById(id);
notFoundIfNull(recipe);
renderJSON(recipe);
}
When I run the test in firefox using the TestRunner at http://localhost:8080/#tests
I get this error message:
Failure, Response status expected:<200> but was:<404>
Now if I run this url http://localhost:8080/recipe/1 in a browser, I get the json responce I'm expecting wich is a json representation of my recipe object.
There is of course a recipe in the database with id 1.
Now here is my question. Why is the test failing when the browser is not. I tryed this in Chrome, IE and FF with the same result.
Any pointers would be much appreciated.
Thanks
-Alain

Thanks eveyone.
Ok I found the answer.
It appears that my test was running before the fixture data was fully loaded.
I was running my tests against a local MySql database.
When I removed the call
Fixtures.deleteDatabase();
The test was running fine.
To fix the problem I am now running my test against a mem database with this in the application.conf file
%test.db.url=jdbc:h2:mem:play;MODE=MYSQL;LOCK_MODE=0

You can use a helper method to add content type to your request
public Request jsonRequest(Request request) {
request.contentType = "application/json";
request.format = "json";
return request;
}
Then your test become
#Test
public void testThatJsonRenderingWorks() {
Response response = GET(jsonRequest(newRequest)), "/recipe/1");
assertIsOk(response);
}
}
You can also you WS classes to do real http tests insted.