public void AddChiefEmployee_ShouldReturnFalse(string login, decimal salary, decimal bonus) { //arrange ChiefEmployee employee = new ChiefEmployee(login, salary, bonus); var employeeRepositoryMock = new Mock <IEmployeeRepository>(); employeeRepositoryMock.Setup(x => x.AddChief(It.Is <ChiefEmployee>(y => y == employee))); var service = new EmployeeService(employeeRepositoryMock.Object); //act var result = service.AddChiefEmployee(employee); //assert employeeRepositoryMock.Verify(x => x.AddChief(employee), Times.Never); Assert.IsFalse(result); }