import static org.junit.Assert.*;
import org.junit.*;

public class ScoreCollectionTest {

    @Test
    public void test() { 
        fail("Not yet implemented");
    }
}

import static org.junit.Assert.*;
import static org.hamcrest.CoreMatchers.*;
import org.junit.*;

public class ScoreCollectionTest {

    @Test
    public void answersArithmeticMeanOfTwoNumbers() {
        // arrange
        ScoreCollection collection = new ScoreCollection();
        collection.add(() -> 5);
        collection.add(() -> 7);

        // act
        int actualResult = collection.arithmeticMean();

        // assert
        assertThat(actualResult, equalTo(6));
    }
}

edit the test to contain more sense data