add tests

This commit is contained in:
Oli Sturm
2026-04-21 15:27:03 +01:00
parent 3e9f0b56c9
commit 62ced3935c
7 changed files with 226 additions and 1 deletions
+1
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@@ -55,4 +55,5 @@ nunit-*.xml
.idea
.vscode
*.user
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@@ -0,0 +1,50 @@
using CsharpOop.Domain;
namespace CsharpOop.Tests;
/// Tests covering domain-layer invariants on the Account aggregate directly,
/// independent of the application layer.
public class AccountTests
{
[Fact]
public void Opening_an_account_with_a_negative_balance_throws()
{
Assert.Throws<ArgumentOutOfRangeException>(() =>
new Account(new AccountId(Guid.NewGuid()), new Money(-1m)));
}
[Fact]
public void Withdrawing_a_zero_amount_throws()
{
var account = new Account(new AccountId(Guid.NewGuid()), new Money(100m));
Assert.Throws<InvalidOperationException>(() => account.Withdraw(new Money(0m)));
}
[Fact]
public void Withdrawing_a_negative_amount_throws()
{
var account = new Account(new AccountId(Guid.NewGuid()), new Money(100m));
Assert.Throws<InvalidOperationException>(() => account.Withdraw(new Money(-10m)));
}
[Fact]
public void Withdrawing_more_than_the_balance_throws()
{
var account = new Account(new AccountId(Guid.NewGuid()), new Money(100m));
Assert.Throws<InsufficientBalanceException>(() => account.Withdraw(new Money(101m)));
}
[Fact]
public void Successive_withdrawals_are_each_applied_to_the_running_balance()
{
var account = new Account(new AccountId(Guid.NewGuid()), new Money(300m));
account.Withdraw(new Money(100m));
account.Withdraw(new Money(100m));
Assert.Equal(100m, account.Balance.Amount);
}
}
@@ -0,0 +1,78 @@
using CsharpOop.Applications;
using CsharpOop.Contracts;
using CsharpOop.Domain;
using CsharpOop.Infrastructure;
namespace CsharpOop.Tests;
/// Tests covering the application-layer use case surface:
/// what the WithdrawMoney feature does from the caller's perspective.
public class WithdrawMoneyHandlerTests
{
private static (WithdrawMoneyHandler handler, InMemoryAccountRepository repository) BuildHandler()
{
var repository = new InMemoryAccountRepository();
var handler = new WithdrawMoneyHandler(repository);
return (handler, repository);
}
[Fact]
public void Withdrawing_from_an_account_reduces_its_balance_by_the_withdrawn_amount()
{
var (handler, repository) = BuildHandler();
var accountId = Guid.NewGuid();
repository.Save(new Account(new AccountId(accountId), new Money(200m)));
handler.Handle(new WithdrawMoneyCommand { AccountId = accountId, Amount = 75m });
var account = repository.GetById(new AccountId(accountId))!;
Assert.Equal(125m, account.Balance.Amount);
}
[Fact]
public void Withdrawing_the_entire_balance_leaves_the_account_at_zero()
{
var (handler, repository) = BuildHandler();
var accountId = Guid.NewGuid();
repository.Save(new Account(new AccountId(accountId), new Money(100m)));
handler.Handle(new WithdrawMoneyCommand { AccountId = accountId, Amount = 100m });
var account = repository.GetById(new AccountId(accountId))!;
Assert.Equal(0m, account.Balance.Amount);
}
[Fact]
public void Withdrawing_from_a_non_existent_account_throws()
{
var (handler, _) = BuildHandler();
var command = new WithdrawMoneyCommand { AccountId = Guid.NewGuid(), Amount = 50m };
Assert.Throws<InvalidOperationException>(() => handler.Handle(command));
}
[Fact]
public void Withdrawing_more_than_the_available_balance_throws()
{
var (handler, repository) = BuildHandler();
var accountId = Guid.NewGuid();
repository.Save(new Account(new AccountId(accountId), new Money(50m)));
Assert.Throws<InsufficientBalanceException>(() =>
handler.Handle(new WithdrawMoneyCommand { AccountId = accountId, Amount = 100m }));
}
[Fact]
public void After_a_failed_withdrawal_the_balance_is_unchanged()
{
var (handler, repository) = BuildHandler();
var accountId = Guid.NewGuid();
repository.Save(new Account(new AccountId(accountId), new Money(50m)));
try { handler.Handle(new WithdrawMoneyCommand { AccountId = accountId, Amount = 999m }); }
catch (InsufficientBalanceException) { }
var account = repository.GetById(new AccountId(accountId))!;
Assert.Equal(50m, account.Balance.Amount);
}
}
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@@ -0,0 +1,26 @@
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@@ -27,8 +27,9 @@ public sealed class Account : AggregateRoot<AccountId>
if (amount.Amount <= 0)
throw new InvalidOperationException("Withdrawal amount must be positive.");
// Sometimes, validation is modelled with custom exceptions instead
if (Balance.Amount - amount.Amount < 0)
throw new InvalidOperationException("Balance cannot go below zero.");
throw new InsufficientBalanceException(Balance, amount);
Balance = Balance.Subtract(amount);
}
@@ -0,0 +1,15 @@
namespace CsharpOop.Domain;
/// Custom domain exception thrown when a withdrawal would cause the balance to go below zero
public sealed class InsufficientBalanceException : InvalidOperationException
{
public Money CurrentBalance { get; }
public Money RequestedAmount { get; }
public InsufficientBalanceException(Money currentBalance, Money requestedAmount)
: base($"Insufficient balance. Current: {currentBalance.Amount:0.00}, Requested: {requestedAmount.Amount:0.00}")
{
CurrentBalance = currentBalance;
RequestedAmount = requestedAmount;
}
}
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@@ -0,0 +1,54 @@
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