Test that shows that how package-private methods are dispatched depends on class loading.

MockingAndClassLoadersTest.java

package org.mockitousage.packageprotected;

import org.junit.Test;
import static org.mockito.Mockito.spy;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.verifyNoMoreInteractions;
import org.mockitoutil.ClassLoaderBuilder;
import org.mockitoutil.TestBase;

public class MockingAndClassLoadersTest extends TestBase {

    public static class ProductionClass {
        String packageProtected() {
            return "package protected";
        }
        public String callPackageProtected() {
            return packageProtected();
        }
    }

    public static class TestClass implements Runnable {
        public void run() {
            ProductionClass c = spy(new ProductionClass());
            assertEquals("package protected", c.callPackageProtected());
            verify(c).callPackageProtected();
            verify(c).packageProtected(); // Fails if multiple class loaders are involved!
            verifyNoMoreInteractions(c);
        }
    }

    /**
     * This confirms that package-protected methods are mockable when everything
     * is in the same class loader.
     */
    @Test
    public void packageProtectedWithoutClassLoaders() throws Exception {
        // Contrast with the test above by loading everything in the same loader.
        Runnable r = new TestClass();
        r.run();
    }

    /**
     * This test creates a separate class loader, which causes Mockito to use
     * its SearchingClassLoader. Once SearchingClassLoader is involved, package
     * protected methods are not mockable! So the package-protected call fails
     * to verify.
     * 
     * <p>This uses AOSP's ClassLoaderBuilder, but any 2nd class loader should
     * be sufficient.
     */
    @Test
    public void packageProtectedAndClassLoaders() throws Exception {
        String testClassName = MockingAndClassLoadersTest.class.getName() + "$TestClass";

        // Run test code in a separate class loader.
        ClassLoader loader = new ClassLoaderBuilder()
                .withPrivateCopy("org.mockito.")
                .withPrivateCopy("org.mockitousage.")
                .build();
        Class<?> testClass = loader.loadClass(testClassName);
        Runnable r = (Runnable) testClass.newInstance();
        r.run();
    }
}

ClassLoaderBuilder.java