[Fact]
public void RunCustomerReportBatchShouldSendReports()
{
    // Arrange
    var customerDataMock = new Mock<ICustomerData>();   
    var reportBuilderMock = new Mock<IReportBuilder>();
    var emailerMock = new Mock<IEmailer>();

    var expectedCustomer = new Customer("fist@sea.com");
    var expectedReportBody = "the report body";

    customerDataMock.Setup(x => x.GetCustomersForCustomerReport())
        .Returns(new[] { expectedCustomer });

    reportBuilderMock.Setup(x => x.CreateCustomerReport(expectedCustomer))
        .Returns(new Report(expectedCustomer.Email, expectedReportBody));

    var sut = new ReportingService(
        customerDataMock.Object, 
        reportBuilderMock.Object, 
        emailerMock.Object);

    // Act
    sut.RunCustomerReportBatch();

    // Assert
    emailerMock.Verify(x => x.Send(expectedCustomer.Email, expectedReportBody));
}