NPE when @SpringBootTest(webEnvironment = RANDOM_PORT) and @WebAppConfiguration are used together

[wilkinsona]

The context fails to load due to a NullPointerException:

java.lang.IllegalStateException: Failed to load ApplicationContext
    at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:124) ~[spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:83) ~[spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.springframework.test.context.web.ServletTestExecutionListener.setUpRequestContextIfNecessary(ServletTestExecutionListener.java:189) ~[spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.springframework.test.context.web.ServletTestExecutionListener.prepareTestInstance(ServletTestExecutionListener.java:131) ~[spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:230) ~[spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:228) [spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:287) [spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) [junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:289) [spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:247) [spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94) [spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) [junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) [junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) [junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) [junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) [junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) [spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70) [spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363) [junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191) [spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86) [.cp/:na]
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) [.cp/:na]
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459) [.cp/:na]
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675) [.cp/:na]
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382) [.cp/:na]
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192) [.cp/:na]
Caused by: java.lang.NullPointerException: null
    at org.springframework.test.context.web.socket.MockServerContainerContextCustomizer.customizeContext(MockServerContainerContextCustomizer.java:38) ~[spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.springframework.boot.test.context.SpringBootContextLoader$ContextCustomizerAdapter.initialize(SpringBootContextLoader.java:270) ~[classes/:na]
    at org.springframework.boot.SpringApplication.applyInitializers(SpringApplication.java:639) ~[classes/:na]
    at org.springframework.boot.SpringApplication.prepareContext(SpringApplication.java:349) ~[classes/:na]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:313) ~[classes/:na]
    at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:111) ~[classes/:na]
    at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:98) ~[spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:116) ~[spring-test-4.3.3.BUILD-SNAPSHOT.jar:4.3.3.BUILD-SNAPSHOT]
    ... 25 common frames omitted

There's no need to use @WebAppConfiguration when you're using @SpringBootTest and, in this case at least, it's harmful. Perhaps we should fail fast, telling the user to remove @WebAppConfiguration?

[wilkinsona]

Another option could be to skip over MockServerContainerContextCustomizer when we're getting the initializers. We could log a warning or error message pointing out the misconfiguration.

[artembilan]

SO question on the matter: http://stackoverflow.com/questions/39237328/nullpointerexception-when-using-springboottest-annotation-with-webenvironment.
I'm inclined to agree with @sbrannen (and with @wilkinsona as well 😉) that it doesn't not make sense to combine webEnvironment with real Embedded Servlet container and @WebAppConfiguration to mock Servlet context.
👍 to "fail fast" and suggest to remove @WebAppConfiguration.

[sbrannen]

Perhaps we should fail fast, telling the user to remove @WebAppConfiguration?

That's the route I'd opt for in order to avoid any further unexpected side effects.

[wilkinsona]

We're going to fail fast

[wilkinsona]

We overlooked #6371 when we decided to fail fast

[sbrannen]

We overlooked #6371 when we decided to fail fast

So the saga continues....

What is your current plan of action?

[wilkinsona]

What is your current plan of action?

We're going to fail fast when the two are used in combination and @SpringBootTest is configured with a non-mock web environment.

[sbrannen]

Sounds good, @wilkinsona! 👍