MockitoMultithreadedTest.java

import org.junit.Test;
import org.mockito.ArgumentCaptor;
import org.mockito.Mockito;

import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import static org.junit.Assert.assertEquals;
import static org.mockito.Mockito.after;
import static org.mockito.Mockito.verify;

public class MockitoMultithreadedTest {
    @Test
    public void shouldCapture10Arguments() throws Exception {
        final MockObj mockObj = Mockito.mock(MockObj.class);
        ExecutorService exec = Executors.newFixedThreadPool(1);
        exec.submit(() -> {
            for (int j = 0; j < 10; j++) {
                mockObj.method(0);
            }
        });
        ArgumentCaptor<Integer> argumentCaptor = ArgumentCaptor.forClass(Integer.class);
        verify(mockObj, after(1000).atLeastOnce()).method(argumentCaptor.capture());
        List<Integer> captured = argumentCaptor.getAllValues();
        assertEquals(10, captured.size());
    }

    private static class MockObj {
        void method(Integer arg) {
            // void
        }
    }
}