public void ShouldReturnNull_IfTeacherIdNotMatched()
{
// Arrange
var teacherId = Guid.NewGuid().ToString();
var classes = new List <StudentClass>()
{
new StudentClass("1A"),
new StudentClass("2A"),
new StudentClass("3A")
};
var queryable = classes.AsQueryable();
var mockedDbSet = new Mock <IDbSet <StudentClass> >();
mockedDbSet.As <IQueryable <StudentClass> >().Setup(m => m.Provider).Returns(queryable.Provider);
mockedDbSet.As <IQueryable <StudentClass> >().Setup(m => m.Expression).Returns(queryable.Expression);
mockedDbSet.As <IQueryable <StudentClass> >().Setup(m => m.ElementType).Returns(queryable.ElementType);
mockedDbSet.As <IQueryable <StudentClass> >().Setup(m => m.GetEnumerator()).Returns(() => queryable.GetEnumerator());
var mockedDbContext = new Mock <IDatabaseContext>();
mockedDbContext.Setup(c => c.StudentClasses).Returns(mockedDbSet.Object);
var studentClassService = new StudentClassService(mockedDbContext.Object);
// Act
var cl = studentClassService.FindByTeacherId(teacherId);
// Assert
Assert.IsNull(cl);
}