Testing Activity Using Mockito Framework

Below is the Simple Calculator Application and I want to test it using Junit4 and mockito Framework i test that application on Junit4 and it works properly but I am facing problem on mockito implementation

CalculatorOperationsInterfaces.java

public interface CalculatorOperationsInterfaces { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); } 

MainActivity.java

import android.os.Bundle; import android.support.v7.app.AppCompatActivity; public class MainActivity extends AppCompatActivity implements CalculatorOperationsInterfaces { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } @Override public double add(double input1, double input2) { return (input1 + input2); } @Override public double subtract(double input1, double input2) { return (input1 - input2); } @Override public double multiply(double input1, double input2) { return (input1 * input2); } @Override public double divide(double input1, double input2) { if(input2==0) return -1; else return (input1 / input2); } } 

CalculatorOperationsMockTest.java

import org.junit.After; import org.junit.Assert; import org.junit.Before; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; import static org.mockito.Mockito.when; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class CalculatorOperationsMockTest { //@Mock annotation is used to create the mock object to be injected @Mock CalculatorOperationsInterfaces calcService; @Before public void setUp() { calcService = new MainActivity(); } @After public void tearDown() { calcService = null; } @Test public void add(){ //add the behavior of calc service to add two numbers when(calcService.add(10.0,20.0)).thenReturn(30.00); //test the add functionality Assert.assertEquals(calcService.add(10.0, 20.0),30.0,0); } } 

I successfully test the Above MainActivity.java using Junit but I am new to Mockito framework when i try to run the CalculatorOperationsMockTest.java File i am getting the below error and i do not know how to solve it

Class not found: "myappmania.local_jvm_unit_test.CalculatorOperationsMockTest"Empty test suite.