Android Library JUnit Test with Robolectric: java.lang.InstantiationException

Question

When trying to run a JUnit test on an Android Library project with Robolectric i get the following error:

java.lang.RuntimeException: java.lang.InstantiationException
    at com.xtremelabs.robolectric.ApplicationResolver.newApplicationInstance(ApplicationResolver.java:56)
    at com.xtremelabs.robolectric.ApplicationResolver.resolveApplication(ApplicationResolver.java:36)
    at com.xtremelabs.robolectric.RobolectricTestRunner.createApplication(RobolectricTestRunner.java:246)
    at com.xtremelabs.robolectric.RobolectricTestRunner.setupApplicationState(RobolectricTestRunner.java:233)
    at com.xtremelabs.robolectric.RobolectricTestRunner.internalBeforeTest(RobolectricTestRunner.java:177)
    at com.xtremelabs.robolectric.RobolectricTestRunner.methodBlock(RobolectricTestRunner.java:157)
    at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.InstantiationException
    at sun.reflect.InstantiationExceptionConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    at java.lang.Class.newInstance0(Unknown Source)
    at java.lang.Class.newInstance(Unknown Source)
    at com.xtremelabs.robolectric.ApplicationResolver.newApplicationInstance(ApplicationResolver.java:54)
    ... 20 more

My first idea was that i made a mistake within the test, so i simplified the test run as much as possible:

import static org.junit.Assert.*;

import org.junit.Test;
import org.junit.runner.RunWith;

import com.xtremelabs.robolectric.RobolectricTestRunner;

@RunWith(RobolectricTestRunner.class)
public class CommonDataTest {

    @Test
    public void test(){
        assertTrue(true);
    }

}

but i still get the same error. I set up the Project as described here: http://robolectric.org/eclipse-quick-start/ The strange thing is that it worked with other Android Library Projects without any problems.

Any help would be appreciated! Thank you in advance!

Answer 1

it seemed that Robolectric was unable to create the Application from my library so i replaced the TestRunner:

import org.junit.runners.model.InitializationError;

import android.app.Application;

import com.xtremelabs.robolectric.RobolectricTestRunner;

public class MyTestRunner extends RobolectricTestRunner {

    public MyTestRunner(Class<?> testClass)
            throws InitializationError {
        super(testClass);
    }

    @Override protected Application createApplication() {
        return new Application() {
        };
    }


}

and used it instead of the RobolectricTestRunner:

@RunWith(MyTestRunner.class)

The tests are running properly now.