Choosing a Data Approach

TUnit offers several ways to provide data to your tests. Use this guide to pick the right one.

Decision Table

Scenario	Approach	Page
Fixed inline values	[Arguments(...)]	Arguments
Data from a method	[MethodDataSource]	Method Data Sources
Shared object with lifecycle	[ClassDataSource<T>]	Class Data Source
Reusable data rows	[TestDataRow<T>]	Test Data Row
All parameter combinations	[MatrixDataSource]	Matrix Tests
Multiple sources on one method	Combined attributes	Combined Data Sources
Hierarchical injection	Nested properties	Nested Data Sources
Custom generic attributes	[GenericArguments<T>]	Generic Attributes

Quick Examples

Inline arguments

[Test]
[Arguments(1, 2, 3)]
[Arguments(0, 0, 0)]
public async Task Add_ReturnsSum(int a, int b, int expected)
{
    await Assert.That(a + b).IsEqualTo(expected);
}

Method data source

[Test]
[MethodDataSource(nameof(GetCases))]
public async Task MyTest(string input)
{
    await Assert.That(input).IsNotEmpty();
}

public static IEnumerable<string> GetCases() => ["hello", "world"];

Class data source (shared fixture)

[ClassDataSource<DatabaseFixture>(Shared = SharedType.PerTestSession)]
public class MyTests(DatabaseFixture db)
{
    [Test]
    public async Task QueryWorks()
    {
        var result = await db.QueryAsync("SELECT 1");
        await Assert.That(result).IsNotNull();
    }
}

Matrix (combinatorial)

[Test]
[MatrixDataSource]
public async Task Multiply(
    [Matrix(2, 3)] int a,
    [Matrix(4, 5)] int b)
{
    await Assert.That(a * b).IsGreaterThan(0);
}
// Generates: (2,4), (2,5), (3,4), (3,5)

Quick Rules

• [Arguments] is the simplest — use it when values are known at compile time.
• [MethodDataSource] is best for computed or complex data.
• [ClassDataSource<T>] manages object lifecycles (initialization, disposal, sharing across tests).
• [MatrixDataSource] generates the Cartesian product of all [Matrix] parameter values.
• Attributes can be combined on a single method — see Combined Data Sources.