public async Task <int> RemoveTransactionAsync(int id)
        {
            var transaction = _context.GetTransactions().SingleOrDefault(t => t.ID == id);

            if (transaction != null)
            {
                _context.DeleteTransaction(transaction);
            }
            return(await _context.SaveChangesAsync());
        }
        public void DeleteTransaction_calls_EfCore_Remove()
        {
            // Arrange
            var mockTransactionSet = new Mock <DbSet <Transaction> >();

            _mockContext.SetupGet(m => m.Transactions).Returns(mockTransactionSet.Object);
            var testTransaction = new Transaction();

            // Act
            _testRepo.DeleteTransaction(testTransaction);

            // Assert
            mockTransactionSet.Verify(m => m.Remove(testTransaction), Times.Once());
        }