DexException Multiple dex files define Ljunit/extenstions/ActiveTestSuite$1;

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Added Espresso 2.0 to the project build.gradle
2. Created a test case (A junit4 based test)
3. Try and run the test runner.

What is the expected output? What do you see instead?

xecution failed for task ':justyoyo:dexJustyoyoDevDebugTest'.
> com.android.ide.common.internal.LoggedErrorException: Failed to run command:
    /Developer/android-sdk-macosx/build-tools/21.1.2/dx --dex --no-optimize --output /Users/chris/Git/Yoyo-Android/justyoyo/build/intermediates/dex/test/justyoyodev/debug --input-list=/Users/chris/Git/Yoyo-Android/justyoyo/build/intermediates/tmp/dex/test/justyoyodev/debug/inputList.txt
  Error Code:
    2
  Output:

    UNEXPECTED TOP-LEVEL EXCEPTION:
    com.android.dex.DexException: Multiple dex files define Ljunit/extensions/ActiveTestSuite$1;
        at com.android.dx.merge.DexMerger.readSortableTypes(DexMerger.java:596)
        at com.android.dx.merge.DexMerger.getSortedTypes(DexMerger.java:554)
        at com.android.dx.merge.DexMerger.mergeClassDefs(DexMerger.java:535)
        at com.android.dx.merge.DexMerger.mergeDexes(DexMerger.java:171)
        at com.android.dx.merge.DexMerger.merge(DexMerger.java:189)
        at com.android.dx.command.dexer.Main.mergeLibraryDexBuffers(Main.java:454)
        at com.android.dx.command.dexer.Main.runMonoDex(Main.java:303)
        at com.android.dx.command.dexer.Main.run(Main.java:246)
        at com.android.dx.command.dexer.Main.main(Main.java:215)
        at com.android.dx.command.Main.main(Main.java:106)

What version of the product are you using? On what operating system?

Target v21, BuildTools 21.1.2, OSx 10.10, Gradle 2.2. 

Please provide any additional information below.

I also have Robolectric enabled. Would this cause a confliction?

Original issue reported on code.google.com by chris.mark.jenkins@gmail.com on 15 Jan 2015 at 12:32