title: Robotium test cannot find activity class
body: <p>I have been using robotium to test my android application. I found it very useful tool so far. Recently we have done a refactoring that would use only one activity in the entire application, each page will be replaced by a fragment. </p>
  
  <p>However, After we start using that activity to run the unit tests, the test complains NoClassDefound error -- it couldn't find the activity class. I don't see anywhere I have change the configuration whatsoever. </p>
  
  <p>Can anybody give a clue what might be wrong , where to check and so on ? </p>
  
  <pre><code>[INFO]     java.lang.RuntimeException: Exception during suite construction
  at android.test.suitebuilder.TestSuiteBuilder$FailedToCreateTests.testSuiteConstructionFailed(T  estSuiteBuilder.java:239)
  at java.lang.reflect.Method.invokeNative(Native Method)
  at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:169)
  at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:154)
  at android.test.InstrumentationTestRunner.onStart(InstrumentationTestRunner.java:529)
  ....
  at dalvik.system.NativeStart.main(Native Method) 
  Caused by: java.lang.NoClassDefFoundError: com.xxx.wallet.HaloActivity
  at com.xxx.wallet.HaloActivityTest.&lt;init&gt;(HaloActivityTest.java:12)
  ... 18 more
  </code></pre>
  
  <p>The app apk is loaded, AndroidManifest.xml should be ok too. </p>