Dexcache==null for Mockito on Robolectric

I’m writing this post as a PSA for anyone else who is pulling their hair out over this.  I started getting the following exception when trying to run tests in Robolectric with Mockito.


java.lang.IllegalArgumentException: dexcache == null (and no default could be found; consider setting the 'dexmaker.dexcache' system property)
at com.google.dexmaker.DexMaker.generateAndLoad(DexMaker.java:359)
at com.google.dexmaker.stock.ProxyBuilder.buildProxyClass(ProxyBuilder.java:252)
at com.google.dexmaker.mockito.DexmakerMockMaker.createMock(DexmakerMockMaker.java:56)
at org.mockito.internal.util.MockUtil.createMock(MockUtil.java:26)
at org.mockito.internal.MockitoCore.mock(MockitoCore.java:51)
at org.mockito.Mockito.mock(Mockito.java:1243)
at org.mockito.internal.configuration.MockAnnotationProcessor.process(MockAnnotationProcessor.java:30)
at org.mockito.internal.configuration.MockAnnotationProcessor.process(MockAnnotationProcessor.java:16)
at org.mockito.internal.configuration.DefaultAnnotationEngine.createMockFor(DefaultAnnotationEngine.java:43)
at org.mockito.internal.configuration.DefaultAnnotationEngine.process(DefaultAnnotationEngine.java:66)
at org.mockito.internal.configuration.InjectingAnnotationEngine.processIndependentAnnotations(InjectingAnnotationEngine.java:71)
at org.mockito.internal.configuration.InjectingAnnotationEngine.process(InjectingAnnotationEngine.java:55)
at org.mockito.MockitoAnnotations.initMocks(MockitoAnnotations.java:108)
at xxx.anpr.handheld.model.when_creating_a_XXX_label.setUp(when_creating_a_XXX_label.java:50)
at sun.reflect.GeneratedMethodAccessor38.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:30)
at org.robolectric.RobolectricTestRunner$2.evaluate(RobolectricTestRunner.java:236)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.robolectric.RobolectricTestRunner$1.evaluate(RobolectricTestRunner.java:177)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:24)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:77)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:195)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:63)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)

Hunting the internet revealed no one, as far as I could see, who’d suffered the same problem.  Worse than that, I’d set up the same sort of thing in a different project without hitting this problem.

But, flash of inspiration.  The problem is with dexcache.  Well dex is kind of like the android version of Java byte code (in a very handwavey kind of way).  But this is in Robolectric.  We shouldn’t be dealing in dex, we should be dealing in good old fashioned byte code, like our fathers and their fathers before them.  And then it hit me, an ingenious work around.

Mockito only started supporting android relatively recently.  If I drop back to version 1.9 it won’t even know to try this dexcache thing!  So remove the reference to version 1.9.5, replace it with 1.9.0 and Bob’s your uncle, working Mocks!

Fixed then, but not fixed that well.

4 thoughts on “Dexcache==null for Mockito on Robolectric

  1. Hello, that fix not work

    Robolectric use JUnit4 not JUnit3 and you will not use InstrumentationTestCase thats why you can call getInstrumentation()

    If anybody knows the solution to this issue please help me

  2. Thanks for this. After pulling my hair for over a day, this made me realize I needed normal mockito (‘org.mockito:mockito-core:1.+’ in gradle) and not the dexmaker version which you normally use on Android (‘com.google.dexmaker:dexmaker-mockito:1.0’)

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