add fp3 tests

This commit is contained in:
Oli Sturm
2026-04-24 16:53:12 +01:00
parent 89faa924bc
commit e61b4d4c11
5 changed files with 519 additions and 0 deletions
+73
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using CsharpFp3.Domain;
namespace CsharpFp3.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_returns_OpeningBalanceMustBeNonNegative()
{
var result = AccountDomain.Open(Guid.NewGuid(), new Money(-1m));
Assert.IsType<AccountError.OpeningBalanceMustBeNonNegative>(result.Error);
}
[Fact]
public void Withdrawing_a_zero_amount_returns_AmountMustBePositive()
{
var account = AccountDomain.Open(Guid.NewGuid(), new Money(100m)).Value;
var result = AccountDomain.Withdraw(account, new Money(0m));
Assert.IsType<AccountError.AmountMustBePositive>(result.Error);
}
[Fact]
public void Withdrawing_a_negative_amount_returns_AmountMustBePositive()
{
var account = AccountDomain.Open(Guid.NewGuid(), new Money(100m)).Value;
var result = AccountDomain.Withdraw(account, new Money(-10m));
Assert.IsType<AccountError.AmountMustBePositive>(result.Error);
}
[Fact]
public void Withdrawing_more_than_the_balance_returns_InsufficientBalance()
{
var account = AccountDomain.Open(Guid.NewGuid(), new Money(100m)).Value;
var result = AccountDomain.Withdraw(account, new Money(101m));
Assert.IsType<AccountError.InsufficientBalance>(result.Error);
}
[Fact]
public void InsufficientBalance_error_reports_the_current_balance_and_attempted_amount()
{
var account = AccountDomain.Open(Guid.NewGuid(), new Money(100m)).Value;
var error = Assert.IsType<AccountError.InsufficientBalance>(
AccountDomain.Withdraw(account, new Money(150m)).Error
);
Assert.Equal(100m, error.Balance.Amount);
Assert.Equal(150m, error.Amount.Amount);
}
[Fact]
public void Successive_withdrawals_are_each_applied_to_the_running_balance()
{
var account = AccountDomain.Open(Guid.NewGuid(), new Money(300m)).Value;
var result1 = AccountDomain.Withdraw(account, new Money(100m));
var updatedAccount1 = result1.Value;
var result2 = AccountDomain.Withdraw(updatedAccount1, new Money(100m));
var updatedAccount2 = result2.Value;
Assert.Equal(100m, updatedAccount2.Balance.Amount);
}
}
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using CsharpFp3.Library;
namespace CsharpFp3.Tests;
/// Tests covering the Result<T,E> type and its extension methods.
public class ResultTests
{
// --- Ok / Fail construction ---
[Fact]
public void Ok_is_success()
{
var result = Result<int, string>.Ok(42);
Assert.True(result.IsSuccess);
Assert.False(result.IsFailure);
}
[Fact]
public void Fail_is_failure()
{
var result = Result<int, string>.Fail("oops");
Assert.True(result.IsFailure);
Assert.False(result.IsSuccess);
}
[Fact]
public void Ok_exposes_value()
{
var result = Result<int, string>.Ok(42);
Assert.Equal(42, result.Value);
}
[Fact]
public void Fail_exposes_error()
{
var result = Result<int, string>.Fail("oops");
Assert.Equal("oops", result.Error);
}
[Fact]
public void Accessing_Value_on_a_failed_result_throws()
{
var result = Result<int, string>.Fail("oops");
Assert.Throws<InvalidOperationException>(() => result.Value);
}
[Fact]
public void Accessing_Error_on_a_successful_result_throws()
{
var result = Result<int, string>.Ok(42);
Assert.Throws<InvalidOperationException>(() => result.Error);
}
// --- Match ---
[Fact]
public void Match_calls_onSuccess_for_Ok()
{
var result = Result<int, string>.Ok(10);
var output = result.Match(v => $"value:{v}", e => $"error:{e}");
Assert.Equal("value:10", output);
}
[Fact]
public void Match_calls_onFailure_for_Fail()
{
var result = Result<int, string>.Fail("bad");
var output = result.Match(v => $"value:{v}", e => $"error:{e}");
Assert.Equal("error:bad", output);
}
// --- Switch ---
[Fact]
public void Switch_calls_onSuccess_for_Ok()
{
var result = Result<int, string>.Ok(7);
var called = false;
result.Switch(_ => called = true, _ => { });
Assert.True(called);
}
[Fact]
public void Switch_calls_onFailure_for_Fail()
{
var result = Result<int, string>.Fail("err");
var called = false;
result.Switch(_ => { }, _ => called = true);
Assert.True(called);
}
// --- Catch ---
[Fact]
public void Catch_returns_Ok_when_no_exception_is_thrown()
{
var result = Result<int, string>.Catch(() => 99, ex => ex.Message);
Assert.True(result.IsSuccess);
Assert.Equal(99, result.Value);
}
[Fact]
public void Catch_returns_Fail_when_an_exception_is_thrown()
{
var result = Result<int, string>.Catch(
() => throw new InvalidOperationException("boom"),
ex => ex.Message
);
Assert.True(result.IsFailure);
Assert.Equal("boom", result.Error);
}
// --- Bind ---
[Fact]
public void Bind_chains_to_the_next_result_on_success()
{
var result = Result<int, string>.Ok(5).Bind(v => Result<string, string>.Ok($"got {v}"));
Assert.Equal("got 5", result.Value);
}
[Fact]
public void Bind_short_circuits_on_failure_without_calling_the_binder()
{
var binderCalled = false;
var result = Result<int, string>
.Fail("nope")
.Bind(v =>
{
binderCalled = true;
return Result<string, string>.Ok($"got {v}");
});
Assert.False(binderCalled);
Assert.Equal("nope", result.Error);
}
[Fact]
public void Bind_propagates_the_inner_failure_when_the_binder_returns_Fail()
{
var result = Result<int, string>.Ok(5).Bind(_ => Result<string, string>.Fail("inner fail"));
Assert.Equal("inner fail", result.Error);
}
// --- Map ---
[Fact]
public void Map_transforms_the_value_on_success()
{
var result = Result<int, string>.Ok(3).Map(v => v * 2);
Assert.Equal(6, result.Value);
}
[Fact]
public void Map_does_not_call_the_mapper_on_failure()
{
var mapperCalled = false;
var result = Result<int, string>.Fail("err").Map(v =>
{
mapperCalled = true;
return v * 2;
});
Assert.False(mapperCalled);
Assert.Equal("err", result.Error);
}
// --- Tap ---
[Fact]
public void Tap_calls_the_action_and_returns_the_original_result_on_success()
{
var seen = -1;
var result = Result<int, string>.Ok(8).Tap(v => seen = v);
Assert.Equal(8, seen);
Assert.Equal(8, result.Value);
}
[Fact]
public void Tap_does_not_call_the_action_on_failure()
{
var called = false;
Result<int, string>.Fail("err").Tap(_ => called = true);
Assert.False(called);
}
// --- TapError ---
[Fact]
public void TapError_calls_the_action_and_returns_the_original_result_on_failure()
{
var seen = "";
var result = Result<int, string>.Fail("bad").TapError(e => seen = e);
Assert.Equal("bad", seen);
Assert.Equal("bad", result.Error);
}
[Fact]
public void TapError_does_not_call_the_action_on_success()
{
var called = false;
Result<int, string>.Ok(1).TapError(_ => called = true);
Assert.False(called);
}
// --- MapError ---
[Fact]
public void MapError_transforms_the_error_on_failure()
{
var result = Result<int, string>.Fail("oops").MapError(e => e.Length);
Assert.Equal(4, result.Error);
}
[Fact]
public void MapError_does_not_call_the_mapper_on_success()
{
var mapperCalled = false;
var result = Result<int, string>.Ok(1).MapError(e =>
{
mapperCalled = true;
return e.Length;
});
Assert.False(mapperCalled);
Assert.Equal(1, result.Value);
}
// --- Select / SelectMany (LINQ support) ---
[Fact]
public void Select_is_equivalent_to_Map()
{
var result = Result<int, string>.Ok(4).Select(v => v + 1);
Assert.Equal(5, result.Value);
}
[Fact]
public void SelectMany_sequences_two_successful_results()
{
var result =
from a in Result<int, string>.Ok(3)
from b in Result<int, string>.Ok(4)
select a + b;
Assert.Equal(7, result.Value);
}
[Fact]
public void SelectMany_short_circuits_when_the_first_result_fails()
{
var result =
from a in Result<int, string>.Fail("first fail")
from b in Result<int, string>.Ok(4)
select a + b;
Assert.Equal("first fail", result.Error);
}
[Fact]
public void SelectMany_short_circuits_when_the_second_result_fails()
{
var result =
from a in Result<int, string>.Ok(3)
from b in Result<int, string>.Fail("second fail")
select a + b;
Assert.Equal("second fail", result.Error);
}
}
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using CsharpFp3.Application;
using CsharpFp3.Domain;
using CsharpFp3.Infrastructure;
using CsharpFp3.Library;
namespace CsharpFp3.Tests;
/// Tests covering the application-layer use case surface:
/// what the WithdrawMoney feature does from the caller's perspective.
public class WithdrawMoneyTests
{
private static (
Func<Guid, decimal, Result<Account, AccountError>> withdraw,
Repository repo
) BuildHandler()
{
var repo = InMemoryAccountRepository.Create();
var withdraw = AccountApplication.CreateWithdrawMoney(repo).Value;
return (withdraw, repo);
}
[Fact]
public void Withdrawing_from_an_account_reduces_its_balance_by_the_withdrawn_amount()
{
var (withdraw, repo) = BuildHandler();
var accountId = Guid.NewGuid();
repo.SaveAccount(AccountDomain.Open(accountId, new Money(200m)).Value);
withdraw(accountId, 75m);
var account = repo.LoadAccount(accountId).Value;
Assert.Equal(125m, account.Balance.Amount);
}
[Fact]
public void Withdrawing_the_entire_balance_leaves_the_account_at_zero()
{
var (withdraw, repo) = BuildHandler();
var accountId = Guid.NewGuid();
repo.SaveAccount(AccountDomain.Open(accountId, new Money(100m)).Value);
withdraw(accountId, 100m);
var account = repo.LoadAccount(accountId).Value;
Assert.Equal(0m, account.Balance.Amount);
}
[Fact]
public void Withdrawing_from_a_non_existent_account_returns_AccountNotFound()
{
var (withdraw, _) = BuildHandler();
var result = withdraw(Guid.NewGuid(), 50m);
Assert.IsType<AccountError.AccountNotFound>(result.Error);
}
[Fact]
public void Withdrawing_more_than_the_available_balance_returns_InsufficientBalance()
{
var (withdraw, repo) = BuildHandler();
var accountId = Guid.NewGuid();
repo.SaveAccount(AccountDomain.Open(accountId, new Money(50m)).Value);
var result = withdraw(accountId, 100m);
Assert.IsType<AccountError.InsufficientBalance>(result.Error);
}
[Fact]
public void AccountNotFound_error_reports_the_requested_account_id()
{
var (withdraw, _) = BuildHandler();
var accountId = Guid.NewGuid();
var error = Assert.IsType<AccountError.AccountNotFound>(
withdraw(accountId, 50m).Error
);
Assert.Equal(accountId, error.AccountId);
}
[Fact]
public void InsufficientBalance_error_reports_the_current_balance_and_attempted_amount()
{
var (withdraw, repo) = BuildHandler();
var accountId = Guid.NewGuid();
repo.SaveAccount(AccountDomain.Open(accountId, new Money(50m)).Value);
var error = Assert.IsType<AccountError.InsufficientBalance>(
withdraw(accountId, 120m).Error
);
Assert.Equal(50m, error.Balance.Amount);
Assert.Equal(120m, error.Amount.Amount);
}
[Fact]
public void After_a_failed_withdrawal_the_balance_is_unchanged()
{
var (withdraw, repo) = BuildHandler();
var accountId = Guid.NewGuid();
repo.SaveAccount(AccountDomain.Open(accountId, new Money(50m)).Value);
withdraw(accountId, 999m);
var account = repo.LoadAccount(accountId).Value;
Assert.Equal(50m, account.Balance.Amount);
}
}
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<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>net10.0</TargetFramework>
<RootNamespace>CsharpFp3.Tests</RootNamespace>
<ImplicitUsings>enable</ImplicitUsings>
<Nullable>enable</Nullable>
<IsPackable>false</IsPackable>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="coverlet.collector" Version="6.0.4" />
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
<PackageReference Include="xunit" Version="2.9.3" />
<PackageReference Include="xunit.runner.visualstudio" Version="3.1.4" />
</ItemGroup>
<ItemGroup>
<Using Include="Xunit" />
</ItemGroup>
<ItemGroup>
<ProjectReference Include="..\csharp-fp3\csharp-fp3.csproj" />
</ItemGroup>
</Project>
+15
View File
@@ -23,6 +23,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "csharp-fp2.Tests", "csharp-
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "csharp-fp3", "csharp-fp3\csharp-fp3.csproj", "{83AFEF87-AAC9-45F4-B803-1BCDF0443BF7}"
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "csharp-fp3.Tests", "csharp-fp3.Tests\csharp-fp3.Tests.csproj", "{B85327F8-AFA8-47E9-97AB-318F74238929}"
EndProject
Global
GlobalSection(SolutionConfigurationPlatforms) = preSolution
Debug|Any CPU = Debug|Any CPU
@@ -129,6 +131,18 @@ Global
{83AFEF87-AAC9-45F4-B803-1BCDF0443BF7}.Release|x64.Build.0 = Release|Any CPU
{83AFEF87-AAC9-45F4-B803-1BCDF0443BF7}.Release|x86.ActiveCfg = Release|Any CPU
{83AFEF87-AAC9-45F4-B803-1BCDF0443BF7}.Release|x86.Build.0 = Release|Any CPU
{B85327F8-AFA8-47E9-97AB-318F74238929}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
{B85327F8-AFA8-47E9-97AB-318F74238929}.Debug|Any CPU.Build.0 = Debug|Any CPU
{B85327F8-AFA8-47E9-97AB-318F74238929}.Debug|x64.ActiveCfg = Debug|Any CPU
{B85327F8-AFA8-47E9-97AB-318F74238929}.Debug|x64.Build.0 = Debug|Any CPU
{B85327F8-AFA8-47E9-97AB-318F74238929}.Debug|x86.ActiveCfg = Debug|Any CPU
{B85327F8-AFA8-47E9-97AB-318F74238929}.Debug|x86.Build.0 = Debug|Any CPU
{B85327F8-AFA8-47E9-97AB-318F74238929}.Release|Any CPU.ActiveCfg = Release|Any CPU
{B85327F8-AFA8-47E9-97AB-318F74238929}.Release|Any CPU.Build.0 = Release|Any CPU
{B85327F8-AFA8-47E9-97AB-318F74238929}.Release|x64.ActiveCfg = Release|Any CPU
{B85327F8-AFA8-47E9-97AB-318F74238929}.Release|x64.Build.0 = Release|Any CPU
{B85327F8-AFA8-47E9-97AB-318F74238929}.Release|x86.ActiveCfg = Release|Any CPU
{B85327F8-AFA8-47E9-97AB-318F74238929}.Release|x86.Build.0 = Release|Any CPU
EndGlobalSection
GlobalSection(SolutionProperties) = preSolution
HideSolutionNode = FALSE
@@ -142,5 +156,6 @@ Global
{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A} = {89C53051-77F9-4C1C-ABE5-6D54AB398471}
{4AFF063B-7125-4783-BE84-E1E9B4E2A462} = {89C53051-77F9-4C1C-ABE5-6D54AB398471}
{83AFEF87-AAC9-45F4-B803-1BCDF0443BF7} = {89C53051-77F9-4C1C-ABE5-6D54AB398471}
{B85327F8-AFA8-47E9-97AB-318F74238929} = {89C53051-77F9-4C1C-ABE5-6D54AB398471}
EndGlobalSection
EndGlobal