Android JUnit Test Runner - java.lang.ClassNotFoundException

Today I've been setting up a test project for my upcoming android-project. First thing I did was using the Eclipse wizard to create a new Android test project for an existing android project.
I quickly threw in a TestSuite that would run all Tests 'below' the current package...

package org.anddev.andengine.test;

import junit.framework.Test;
import junit.framework.TestSuite;
import android.test.suitebuilder.TestSuiteBuilder;

public class AllTests extends TestSuite {
 public static Test suite() {
  return new TestSuiteBuilder(AllTests.class).includeAllPackagesUnderHere().build();
 }
}

... and a dummy TestCase ...

package org.anddev.andengine.test.bla;

import junit.framework.Assert;
import android.test.AndroidTestCase;

public class SomeTest extends AndroidTestCase {

    public void testSomething() throws Throwable {
       Assert.assertTrue(1 + 1 == 2);
    }

    public void testSomethingElse() throws Throwable {
       Assert.assertTrue(1 + 1 == 3);
    }
}

Either running the Android test project right from Eclipse or from the command-line resulted in:

E:\sdk\android\tools>adb shell am instrument -w org.anddev.andengine.test/android.test.InstrumentationTestRunner


INSTRUMENTATION_RESULT: shortMsg=Unable to instantiate instrumentation ComponentInfo{org.anddev.andengine.test/android.test.InstrumentationTestRunner}: java.lang.ClassNotFoundException: android.test.InstrumentationTestRunner in loader dalvik.system.PathClassLoader@4001b4f8
INSTRUMENTATION_RESULT: longMsg=java.lang.RuntimeException: Unable to instantiate instrumentation ComponentInfo{org.anddev.andengine.test/android.test.InstrumentationTestRunner}: java.lang.ClassNotFoundException: android.test.InstrumentationTestRunner in loader dalvik.system.PathClassLoader@4001b4f8
INSTRUMENTATION_CODE: 0

So what was the problem and how did I fix this?

Due to the fact that the project I wanted to test was a kind of libary, which had no need for an application or activity tag or similar i had deleted it from the AndroidManifest.xml, like this:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="org.anddev.andengine"
 android:versionCode="1"
 android:versionName="1.0">

 <uses-sdk android:minSdkVersion="4" />
</manifest> 

... so the only thing I had to change was an empty <application> tag to the AndroidManifest.xml !

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="org.anddev.andengine"
 android:versionCode="1"
 android:versionName="1.0">

 <uses-sdk android:minSdkVersion="4" />
 <application />
</manifest> 

Hope this helps =)

Best Regards,
Nicolas