duempelkas/tests/Duempelkas.Tests/TransferServiceTests.cs

using Duempelkas.Domain.Entities;
using Duempelkas.Domain.Enums;
using Duempelkas.Infrastructure.Persistence;
using Duempelkas.Infrastructure.Services;
using FluentAssertions;
using Microsoft.EntityFrameworkCore;
using Xunit;

namespace Duempelkas.Tests;

public class TransferServiceTests : IDisposable
{
    private readonly FinanceDbContext _db;
    private readonly EntryService _entryService;
    private readonly BalanceQueryService _balanceQueryService;

    public TransferServiceTests()
    {
        var options = new DbContextOptionsBuilder<FinanceDbContext>()
            .UseSqlite("Data Source=duempelkas-transfer-tests;Mode=Memory;Cache=Shared")
            .Options;

        _db = new FinanceDbContext(options);
        _db.Database.OpenConnection();
        _db.Database.EnsureCreated();

        var dbFactory = new TestDbContextFactory(options);

        _entryService = new EntryService(dbFactory);
        _balanceQueryService = new BalanceQueryService(dbFactory);
    }

    [Fact]
    public async Task CreateTransfer_CreatesLinkedExpenseAndIncome()
    {
        var accountA = new Account { Name = "Account A" };
        var accountB = new Account { Name = "Account B" };
        _db.Accounts.AddRange(accountA, accountB);
        await _db.SaveChangesAsync();

        await _entryService.CreateTransferAsync(accountA.Id, accountB.Id, new DateTime(2026, 3, 15), "Test Transfer", 100.00m);

        var entries = await _db.Entries.ToListAsync();
        entries.Should().HaveCount(2);

        var sourceEntry = entries.Single(e => e.AccountId == accountA.Id);
        sourceEntry.Type.Should().Be(EntryType.Expense);
        sourceEntry.Amount.Should().Be(100.00m);
        sourceEntry.Title.Should().Be("Test Transfer");
        sourceEntry.DisplayId.Should().Be("2026-001");

        var targetEntry = entries.Single(e => e.AccountId == accountB.Id);
        targetEntry.Type.Should().Be(EntryType.Income);
        targetEntry.Amount.Should().Be(100.00m);
        targetEntry.DisplayId.Should().Be("2026-002");

        var links = await _db.TransferLinks.ToListAsync();
        links.Should().HaveCount(1);
        links[0].SourceEntryId.Should().Be(sourceEntry.Id);
        links[0].TargetEntryId.Should().Be(targetEntry.Id);

        var balanceA = await _balanceQueryService.GetAccountBalanceAsync(accountA.Id);
        balanceA.TotalBalance.Should().Be(-100.00m);

        var balanceB = await _balanceQueryService.GetAccountBalanceAsync(accountB.Id);
        balanceB.TotalBalance.Should().Be(100.00m);
    }

    [Fact]
    public async Task DeleteTransfer_SoftDeletesBothSides()
    {
        var accountA = new Account { Name = "Account A" };
        var accountB = new Account { Name = "Account B" };
        _db.Accounts.AddRange(accountA, accountB);
        await _db.SaveChangesAsync();

        await _entryService.CreateTransferAsync(accountA.Id, accountB.Id, new DateTime(2026, 3, 15), "Test Transfer", 100.00m);
        var sourceEntry = await _db.Entries.FirstAsync(e => e.AccountId == accountA.Id);

        await _entryService.DeleteEntryAsync(sourceEntry.Id);

        _db.ChangeTracker.Clear();
        var entries = await _db.Entries.ToListAsync();
        entries.Should().HaveCount(2);
        entries.Should().AllSatisfy(e => e.IsDeleted.Should().BeTrue());

        var links = await _db.TransferLinks.ToListAsync();
        links.Should().HaveCount(1);

        var balanceA = await _balanceQueryService.GetAccountBalanceAsync(accountA.Id);
        balanceA.TotalBalance.Should().Be(0m);

        var balanceB = await _balanceQueryService.GetAccountBalanceAsync(accountB.Id);
        balanceB.TotalBalance.Should().Be(0m);
    }

    [Fact]
    public async Task CreateTransfer_SameAccount_Throws()
    {
        var account = new Account { Name = "Account A" };
        _db.Accounts.Add(account);
        await _db.SaveChangesAsync();

        var act = () => _entryService.CreateTransferAsync(account.Id, account.Id, DateTime.Today, "Bad Transfer", 50m);
        await act.Should().ThrowAsync<InvalidOperationException>();
    }

    public void Dispose()
    {
        _db.Database.CloseConnection();
        _db.Dispose();
    }

    private sealed class TestDbContextFactory : IDbContextFactory<FinanceDbContext>
    {
        private readonly DbContextOptions<FinanceDbContext> _options;

        public TestDbContextFactory(DbContextOptions<FinanceDbContext> options)
        {
            _options = options;
        }

        public FinanceDbContext CreateDbContext() => new(_options);

        public Task<FinanceDbContext> CreateDbContextAsync(CancellationToken cancellationToken = default)
            => Task.FromResult(new FinanceDbContext(_options));
    }
}