Creating Custom Fixtures

Fixture Structure

A fixture consists of three optional parts:

Part	Location	Purpose
Setup	Constructor	Initialize resources
State	Properties/Methods	Expose data to tests
Teardown	`Dispose()` / `DisposeAsync()`	Clean up resources

Example: Building TmpDirectoryFixture

Let's create a fixture that provides a unique temporary directory for each test scope and automatically cleans it up afterward.

Step 1: Basic Structure

Start with the minimal fixture structure:

using FEFF.TestFixtures;

[Fixture]
public class TmpDirectoryFixture
{
    public string Path { get; }

    public TmpDirectoryFixture()
    {
        Path = Directory.CreateTempSubdirectory().FullName;
    }
}

Key elements:

[Fixture] attribute - Marks the class for discovery by the framework
Path property - Exposes the directory path to tests
Constructor - Creates the temporary directory (Setup)

Step 2: Add Teardown

Implement IDisposable to clean up the directory:

[Fixture]
public class TmpDirectoryFixture : IDisposable
{
    public string Path { get; }

    public TmpDirectoryFixture()
    {
        Path = Directory.CreateTempSubdirectory().FullName;
    }

    public void Dispose()
    {
        Directory.Delete(Path, true);
    }
}

Note: The framework also supports IAsyncDisposable for fixtures requiring asynchronous cleanup. Implement DisposeAsync() instead of Dispose() when your teardown logic involves async operations (e.g., database connections, network calls, file I/O).

    public async ValueTask DisposeAsync()
    {
        // Async cleanup logic here
        await Task.Delay(10); // Example: upload logs before deletion
        Directory.Delete(Path, true);
    }

Step 3: Add Error Handling

Protect against disposal errors:

[Fixture]
public class TmpDirectoryFixture : IDisposable
{
    public string Path { get; }

    public TmpDirectoryFixture()
    {
        Path = Directory.CreateTempSubdirectory().FullName;
    }

    public void Dispose()
    {
        try
        {
            Directory.Delete(Path, true);
        }
        catch (DirectoryNotFoundException)
        {
            // Directory already deleted - ignore
        }
    }
}

Resource	Description
Source Code	Full implementation of `TmpDirectoryFixture` with options support
Unit Tests	Comprehensive test coverage
Options Tests	Configuration and options usage examples