akka-http-testkit: system must not be null! when using JUnitRouteTest

[moleksyuk]

Hi,

I'm running an example of a test for Route Testkit from the official documentation with small modification:

public class MyAppServiceTest extends JUnitRouteTest {

    // THIS IS SMALL MODIFICATION - I TRY TO ACCESS MATERIALIZER
    // IF I COMMENT IT - EVERYTHING WORKS OK WITH THE LATEST AKKA
    // IT'S A SIMPLIFIED TEST AND IN MY CASE I NEED MATERIALIZER
    private Materializer materializer = materializer();

    TestRoute appRoute = testRoute(new MyAppService().createRoute());

    @Test
    public void testCalculatorAdd() {
        // test happy path
        appRoute.run(HttpRequest.GET("/calculator/add?x=4.2&y=2.3"))
                .assertStatusCode(200)
                .assertEntity("x + y = 6.5");

        // test responses to potential errors
        appRoute.run(HttpRequest.GET("/calculator/add?x=3.2"))
                .assertStatusCode(StatusCodes.NOT_FOUND) // 404
                .assertEntity("Request is missing required query parameter 'y'");

        // test responses to potential errors
        appRoute.run(HttpRequest.GET("/calculator/add?x=3.2&y=three"))
                .assertStatusCode(StatusCodes.BAD_REQUEST)
                .assertEntity("The query parameter 'y' was malformed:\n" +
                        "'three' is not a valid 64-bit floating point value");
    }
}

Everything works great with:

• akka-cluster_2.12:2.5.22
• akka-http_2.12:10.1.8
• akka-http-testkit_2.12:10.1.8

But after upgrade to:

• akka-cluster_2.12:2.6.4
• akka-http_2.12:10.2.4
• akka-http-testkit_2.12:10.2.4

I'm getting exception:

system must not be null!
java.lang.NullPointerException: system must not be null!
	at java.base/java.util.Objects.requireNonNull(Objects.java:247)
	at akka.actor.ExtensionId.apply(Extension.scala:78)
	at akka.actor.ExtensionId.apply$(Extension.scala:77)
	at akka.stream.SystemMaterializer$.apply(SystemMaterializer.scala:31)
	at akka.actor.ExtensionId.get(Extension.scala:96)
	at akka.actor.ExtensionId.get$(Extension.scala:96)
	at akka.stream.SystemMaterializer$.get(SystemMaterializer.scala:32)
	at akka.http.javadsl.testkit.ActorSystemResource.materializer(JUnitRouteTest.scala:66)
	at akka.http.javadsl.testkit.JUnitRouteTestBase.materializer(JUnitRouteTest.scala:26)
	at akka.bug.MyAppServiceTest.<init>(MyAppServiceTest.java:15)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
	at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
	at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:250)
	at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:260)
	at org.junit.runners.BlockJUnit4ClassRunner$2.runReflectiveCall(BlockJUnit4ClassRunner.java:309)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:306)
	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:110)
	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:38)
	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:62)
	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:51)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:567)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
	at com.sun.proxy.$Proxy2.processTestClass(Unknown Source)
	at org.gradle.api.internal.tasks.testing.worker.TestWorker.processTestClass(TestWorker.java:119)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:567)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
	at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:182)
	at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:164)
	at org.gradle.internal.remote.internal.hub.MessageHub$Handler.run(MessageHub.java:414)
	at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
	at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:48)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:56)
	at java.base/java.lang.Thread.run(Thread.java:830)

It fails for example test from

Steps to reproduce:

1. Download akka-bug.zip akka-bug.zip

2. Unzip it

3. Cd to akka-bug

4. Run ./gradlew clean build

Actual result: Test failed. Expected result: Test passed.

[sgc109]

@moleksyuk I had a same Issue, but I resolved it by calling materializer() method in a method with @ Before annotation attached.

[jrudolph]

@moleksyuk I had a same Issue, but I resolved it by calling materializer() method in a method with @ Before annotation attached.

Thanks for providing that information. Maybe we should add that to the Javadoc for the materializer and system definitions in JUnitRouteTestBase.