This post explains how to verify the order in which multiple instances are called. For example lets consider the below class

Class2

package package5;

public class Class2 {
    public void method1() {
        System.out.println("Class2 method1");
    }
}

Class3

package package5;

public class Class3 {
    public void method1() {
        System.out.println("Class3 method1");
    }
}

Class4

package package5;

public class Class4 {
    public void method1() {
        System.out.println("Class4 method1");
    }
}

All the above mentioned class methods are called by Class1 as shown below

Class1

package package5;

public class Class1 {
    private Class2 class2;
    private Class3 class3;
    private Class4 class4;
    
    public void method1() {
        class2.method1();
        class3.method1();
        class4.method1();
    }
}

To verify the order in which objects of all the three classes (ie., Class2, Class3, and Class4) are used. We use an instance of InOrder class which will contain the objects to be verified. We use Mockito’s static inOrder method to create an instance of InOrder class as shown below. We pass the objects as a paramter

InOrder inOrder = Mockito.inOrder(class2, class4, class3);

Now we mention the order by using the InOrder’s verify method as shown below
inOrder.verify(class2).method1();
inOrder.verify(class3).method1();
inOrder.verify(class4).method1();

Below is the complete code

Class1Test

package package5;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InOrder;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.runners.MockitoJUnitRunner;

@RunWith(MockitoJUnitRunner.class)
public class Class1Test {
    @InjectMocks
    private Class1 class1;
    
    @Mock
    private Class2 class2;
    
    @Mock
    private Class3 class3;
    
    @Mock
    private Class4 class4;
    
    @Test
    public void testMethod1() {
        class1.method1();
        InOrder inOrder = Mockito.inOrder(class2, class4, class3);
        inOrder.verify(class2).method1();
        inOrder.verify(class3).method1();
        inOrder.verify(class4).method1();
    }
}