PowerMock multiple matching constructors; (variable length array constructor vs no-param constructor)

Question

I am trying to Mock constructor with no args in ResourceConfig.class. It happens that ResourceConfig has two constructors: (among other ones):

public ResourceConfig()
public ResourceConfig(Class... class)

PowerMock (1.7.3) fails to get the right constructor. I would consider this as a bug; but perhaps there is a solutoin to it(?)

Code:

import org.glassfish.jersey.server.ResourceConfig;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

import static org.powermock.api.mockito.PowerMockito.mock;
import static org.powermock.api.mockito.PowerMockito.whenNew;

@RunWith(PowerMockRunner.class)
@PrepareForTest( ResourceConfig.class )
public class StackOverflowTest {


  @Test
  public void toStackOvflow2() throws Exception {

    ResourceConfig resConf = mock(ResourceConfig.class);
    whenNew(ResourceConfig.class).withNoArguments().thenReturn(resConf);

    //WHATEVER...
  }

}

This produces:

org.powermock.reflect.exceptions.TooManyConstructorsFoundException: Several matching constructors found, please specify the argument parameter types so that PowerMock can determine which method you're referring to. Matching constructors in class org.glassfish.jersey.server.ResourceConfig were:
org.glassfish.jersey.server.ResourceConfig( )
org.glassfish.jersey.server.ResourceConfig( [Ljava.lang.Class;.class )

at org.powermock.reflect.internal.ConstructorFinder.throwExceptionWhenMultipleConstructorMatchesFound(ConstructorFinder.java:89) ...

Any ideas?

Answer 1

You can suppress the multiple constructors, for example:

@Test
public void toStackOvflow2() throws Exception {
    ResourceConfig resConf = mock(ResourceConfig.class);

    // suppress TooManyConstructorsFoundException
    MemberModifier.suppress(MemberMatcher.constructorsDeclaredIn(ResourceConfig.class));
    whenNew(ResourceConfig.class).withNoArguments().thenReturn(resConf);

    // verifying that the expected ResourceConfig instance is returned when using the default ctor ...
    assertSame(resConf, new ResourceConfig());
}

This test passes with:

• PowerMock 1.7.3
• Jersey 2.26

Answer 2

Example for File class that can receive a String or an Uri :

whenNew(File.class).withParameterTypes(String.class).withArguments(any(String.class)).thenReturn(mockFile);

Best approach(if you know the String value in this case):

whenNew(File.class).withArguments(eq("SOME STRING")).thenReturn(mockFile);