构造函数禁止与PowerMock + Mockito一起使用

Question

I have a class that implements singleton as

public class UMR {

private static UMR umr =  new UMR();

private MR mr;

private UMR(){
    this.mr = MR.getInstance();
}

public static UMR getInstance() {
    return umr;
}

}

and here is my test method code

@Test
public void test(){

    suppress(constructor(UMR.class));   

    mockStatic(UMR.class);

    UMR umr = PowerMockito.mock(UMR.class);

    when(UMR.getInstance()).thenReturn(umr);    

    System.out.println("End");

}

annotations used and imports:

import static org.powermock.api.mockito.PowerMockito.mockStatic;
import static org.powermock.api.mockito.PowerMockito.when;
import static org.powermock.api.support.membermodification.MemberMatcher.constructor;
import static org.powermock.api.support.membermodification.MemberModifier.suppress;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)
@PrepareForTest({UMR.class})

I do not want the private constructor to be called but it still calls the constructor even after suppressing the constructor successfully in first statement.

Please suggest if I am doing anything wrong.

Answer 1

An constructor in this line is called before the constructor is suppressed.

private static UMR umr =  new UMR()

You have to use the @SuppressStaticInitializationFor in this case.

Answer 2

Could you move to a lazy initialising singleton pattern?

public class UMR {
    private static UMR umr;

    private MR mr;

    private UMR(){
        this.mr = MR.getInstance();
    }

    public static UMR getInstance() {
        // double locked lazy initializing singleton
        if (umr==null) {
            synchronized(UMR.class) {
                // when we get here, another thread may have already beaten us
                // to the init
                if(umr==null) {
                    // singleton is made here on first use via the getInstance
                    // as opposed to the original example where the singleton
                    // is made when anything uses the type
                    umr = new UMR();
                }
            }
        }
        return umr;
    }
}