Data Generators

Prova allows you to create custom, reusable data sources by inheriting from the DataSourceGeneratorAttribute class. This is similar to xUnit's DataAttribute and enables complex data generation logic that can be shared across multiple tests.

Creating a Custom Data Generator

To create a custom data generator, inherit from DataSourceGeneratorAttribute and implement the GetData() method. This method should return an IEnumerable<object?[]>, where each object?[] represents a row of data for your test method.

Simple Range Generator

using Prova;
using System.Collections.Generic;

public class RangeDataAttribute : DataSourceGeneratorAttribute
{
    private readonly int _start;
    private readonly int _count;

    public RangeDataAttribute(int start, int count)
    {
        _start = start;
        _count = count;
    }

    public override IEnumerable<object?[]> GetData()
    {
        for (int i = 0; i < _count; i++)
        {
            yield return new object?[] { _start + i };
        }
    }
}

Using Custom Data Generators

You can apply your custom attribute to any test method marked with [Theory].

public class MyTests
{
    [Theory]
    [RangeData(1, 5)]
    public void Test_Range(int value)
    {
        Assert.True(value >= 1 && value <= 5);
    }
}

Multiple Generators

You can apply multiple custom generators to the same test method. Prova will execute the test for each row provided by each generator.

[Theory]
[RangeData(1, 3)]
[RangeData(10, 2)]
public void Test_MixedRanges(int value)
{
    // Executes for 1, 2, 3, 10, 11
}

Class-Level Data Generators

Custom data generators can also be applied at the class level to provide data for the class constructor.

[RangeData(100, 2)]
public class MyClassTests
{
    private readonly int _data;

    public MyClassTests(int data)
    {
        _data = data;
    }

    [Fact]
    public void Test()
    {
        Assert.True(_data == 100 || _data == 101);
    }
}

Combining Class and Method Data

If both class-level and method-level data sources are used, Prova will generate a Cartesian product of the data rows.

[RangeData(1, 2)] // Class-level
public class CombinedTests
{
    public CombinedTests(int classData) { ... }

    [Theory]
    [InlineData(""A"")]
    [InlineData(""B"")]
    public void Test(string methodData)
    {
        // Executes:
        // (1, ""A"")
        // (1, ""B"")
        // (2, ""A"")
        // (2, ""B"")
    }
}

Skipping Data Rows

You can use the Skip property on your custom attribute to skip all data rows provided by that generator.

[Theory]
[RangeData(1, 5, Skip = ""Temporarily disabled"")]
public void Test_Skipped(int value) { ... }