---
applyTo: "Fuchs.Tests/**,**/*Tests/**,**/*Tests.cs"
---

# Testing Instructions

## Framework
- Tests use **xUnit** on **.NET 10** (e.g., `Fuchs.Tests`).
- Run via Visual Studio Test Explorer or `dotnet test`.

## Conventions
- One test class per unit under test; name it `<TypeUnderTest>Tests`.
- Name test methods `Method_Scenario_ExpectedResult` (e.g., `ReadBalance_EmptyString_ThrowsInvalidDataException`).
- Use `[Theory]` + `[InlineData]` for parameterized cases; `[Fact]` for single cases.
- Arrange / Act / Assert structure; keep tests deterministic and independent (no shared mutable state, no real network/DB calls).

## What to Cover
- Pure parsing/algorithmic helpers (MT940 parsing, date/decimal parsing, HTML cleanup, OData envelope handling, entity helpers) — these are the highest-value, side-effect-free targets.
- For library classes that accept `ILogger<T>?`, pass `NullLogger<T>.Instance` (or a test logger) in tests.

## Workflow
- After any code change, build the full solution and run the affected test project before concluding.
- Treat a green run (e.g., `Fuchs.Tests` all passing) as the validation gate; never leave the suite red.
- When fixing a bug, add or update a test that reproduces it where practical.