Null Pointer Exception When Mocking Method With No Parameters in Android Ui Test

[simon1867]

I get a crash when I mock a method in an interface that doesn't take any parameters. This only happens in Android Espresso tests. I've replicated the same conditions in a unit test with robolectric and that problem doesn't exist.

I created a repo that has a ui test with the crash
https://github.com/simon-the-canadian/mockito-android-ui-test-null-pointer

java.lang.NullPointerException: Attempt to get length of null array
at org.mockito.internal.invocation.MatcherApplicationStrategy.getMatcherApplicationType(MatcherApplicationStrategy.java:90)
at org.mockito.internal.invocation.MatcherApplicationStrategy.getMatcherApplicationStrategyFor(MatcherApplicationStrategy.java:53)
at org.mockito.internal.invocation.InvocationMatcher.argumentsMatch(InvocationMatcher.java:152)
at org.mockito.internal.invocation.InvocationMatcher.matches(InvocationMatcher.java:81)
at org.mockito.internal.stubbing.InvocationContainerImpl.findAnswerFor(InvocationContainerImpl.java:78)
at org.mockito.internal.handler.MockHandlerImpl.handle(MockHandlerImpl.java:88)
at org.mockito.internal.handler.NullResultGuardian.handle(NullResultGuardian.java:32)
at org.mockito.internal.handler.InvocationNotifierHandler.handle(InvocationNotifierHandler.java:36)
at com.android.dx.mockito.InvocationHandlerAdapter.invoke(InvocationHandlerAdapter.java:61)
at java.lang.reflect.Proxy.invoke(Proxy.java:393)
at $Proxy5.getSampleValue(Unknown Source)
at myawsomedomain.com.myapplication.UiTest.employeeSearchTest(UiTest.java:40)
at java.lang.reflect.Method.invoke(Native Method)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at android.support.test.internal.statement.UiThreadStatement.evaluate(UiThreadStatement.java:55)
at android.support.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:270)
at org.junit.rules.RunRules.evaluate(RunRules.java:20)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:27)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:59)
at android.support.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:262)
at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1879)

[ChristianSchwarz]

Seems like the Invocation.getRawArguments() returns illegaly an null array. I looked into it and found 3 places in package org.mockito.internal.creation.bytebuddy were an Invocation instance is created with raw arguments:

• MockMethodAdvice.handle(Object, Method, Object[])
• MockMethodInterceptor.DispatcherDefaultingToRealMethod.interceptAbstract(Object, MockMethodInterceptor, Object, Method, Object[])
• MockMethodInterceptor.DispatcherDefaultingToRealMethod.interceptSuperCallable(Object, MockMethodInterceptor, Method, Object[], Callable<?>)

@raphw Do you have an idea why an null array is passed here?

[raphw]

This does not look possible from the code. Byte Buddy never assigns null to AllArguments either. At the same time, from ArgumentsProcessor::expandVarArgs, it seems like args being null is a legitimate case.

As this is run in an instrumentation test, it is neither Byte Buddy which is creating the byte code, it is a fork of dexmaker which is causing the problem: https://github.com/blueapron/dexmaker

This problem does not occur with mockito-android which we still have not released.

[simon1867]

Do you guys have an idea for the timeframe when mockito-android will be released?

[TimvdLippe]

Soon rather than later. We are still tinkering out the publication mechanism. E.g. separate artifact, separate repo?