How to mock interfaces in EvoSuite tests?

[Matthew Sammut]

I have a simple toy class whose purpose is to investigate how automated unit-test generation works with EvoSuite.

The class is as follows:

package mylib;

public class ClassWithInterfaceField {
   private InterfaceExample example;


   private ClassWithInterfaceField(InterfaceExample example) {
      this.example = example;
   }


   public int getSwag() {
      return example.getValue(null, 20);
   }

   public int performSwagAndLog(int swag) {
      example.performSwag();
      System.out.println("hmmm");
      return swag + 1;
   }
}

where `InterfaceExample` is defined in a separate file as follows:

    package mylib;

public interface InterfaceExample {

void performSwag();

int getValue(InterfaceExample example, int flag);

}

EvoSuite seems to be unable to generate any tests for `ClassWithInterfaceField`.

Even when I add `-Dp_functional_mocking=1.0 -Dp_reflection_on_private=1.0 -Dreflection_start_percent=1.0 -Dfunctional_mocking_percent=1.0` to the console parameters, EvoSuite does not seem to be able to mock the `InterfaceExample` as intended, as EvoSuite's output seems to always be as follows:

package mylib;


import org.junit.Test;
import static org.junit.Assert.*;
import org.evosuite.runtime.EvoRunner;
import org.evosuite.runtime.EvoRunnerParameters;
import org.junit.runner.RunWith;


@RunWith(EvoRunner.class) @EvoRunnerParameters(mockJVMNonDeterminism = true, useVFS = true, useVNET = true, resetStaticState = true, separateClassLoader = true, useJEE = true)
public class ClassWithInterfaceField_ESTest extends ClassWithInterfaceField_ESTest_scaffolding {
   @Test
   public void notGeneratedAnyTest() {
       // EvoSuite did not generate any tests
   }
 }

I have read online that EvoSuite has the ability to mock interfaces using Mockito. Is it true that EvoSuite supports mocking? And what do I need to do to generate tests for this class?

[Michel Zerbinati]

Hi Matthew,

Have you tried to change the "private ClassWithInterfaceField(InterfaceExample example)" method to "public ClassWithInterfaceField(InterfaceExample example)" to verify how does this behave?