VertX JUnit 5 MongoDB test does not complete (TimeoutException) or completes too early (testContext.awaitCompletion not working) - mongodb

Question

Background:
During migration from JUnit4 to JUnit5 using VertX I read the migration guides which explain:
how to use the changed Promise and Future Vertx interfaces
how to VertxTestContext, Vertx auto-injection in Vertx Tests
how to use testContext.awaitCondition(), textContext.completing(), testContext.completeNow() etc.
Having this information in mind I wrote the following test:
Test Code:
import io.vertx.core.Promise;
import io.vertx.core.Future;
#ExtendWith(VertxExtension.class)
class RestApiTest {
#BeforeAll
static void setUpMongoDatabase() throws IOException {
(...)
}
#BeforeEach
void setUp(Vertx vertx, VertxTestContext ctx) {
vertx.deployVerticle(ApiVerticle.class.getName(), options, ctx.completing());
return WebClient.create(vertx);
}
#AfterEach
void tearDown(Vertx vertx, VertxTestContext testContext) {
assertThat(vertx.deploymentIDs().size(), is(equalTo(2)));
}
#AfterAll
static void stopMongoDatabase() {
(...)
}
#Test
void test(Vertx vertx, VertxTestContext testContext) {
Future<Void> insertFuture = insertTestData();
future.setHandler(testContext.completing());
// This ether throws a TimeoutException or does not block until the insert completed
testContext.awaitCompletion(5, TimeUnit.SECONDS);
// assert
mongoClient.findOne(COLLECTION, QUERY, result -> {
if (result.succeeded()) testContext.completeNow();
else testContext.failNow();
});
}
Future<Void> insertTestData() {
Promise<Void> promise = Promise.promise();
Future<Void> future = promise.future();
mongoClient.insert(COLLECTION, QUERY, result -> {
if (result.succeeded()) {
promise.complete();
} else {
promise.fail();
}
});
return future;
}
}
Problem:
testContext.awaitCompletion() ether throws a TimeoutException
or does not block until the async insert completed so that my assert returns successfully
Question:
How can I wait for the async mongo query to complete before I continue with my test?

Answer 1

The problem was that I am using the VertX Promise and Future classes:
those classes only work on a VertX Verticle
my insertTestData() method is not executed on a Verticle
One solution is to use the java.util.concurrent.ReentrantLock and Condition classes instead:
#Test
void test() {
insertTestData(); // This is now synchronous as required
// assert
mongoClient.findOne(COLLECTION, QUERY, result -> {
if (result.succeeded()) testContext.completeNow();
else testContext.failNow();
});
}
void insertTestData() {
ReentrantLock lock = new ReentrantLock();
Condition condition = lock.newCondition();
mongoClient.insert(COLLECTION, QUERY, result -> {
if (result.succeeded()) {
lock.lock();
try {
condition.signal();
} finally {
lock.unlock();
}
} else {
fail();
}
});
lock.lock();
try {
condition.await(5, TimeUnit.SECONDS);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
} finally {
lock.unlock();
}
}
}