public async Task AddAsync_AddsItemToDatabase()
{
var numberOfItemsInDatabase = await _context.Subjects.AsQueryable().CountAsync();
await _service.CreateEntityAsync(new SubjectDto { Id = "testSubject1", Name = "Test Subject", LecturerId = "1" });
_context.Subjects.AsQueryable().CountAsync().Result.Should().Be(numberOfItemsInDatabase + 1);
_validator.VerifyAll();
}