v2 v3   Info

xUnit1042

"The member referenced by the MemberData attribute returns untyped data rows"

Cause

xUnit.net offers a strongly-typed TheoryData<> class which can be used instead of IEnumerable<object[]> when returning member data. For v3 projects, you can also use IEnumerable<TheoryDataRow<>> and IAsyncEnumerable<TheoryDataRow<>>, as well as supporting Task<> or ValueTask<> around the entire data set.

Reason for rule

Using TheoryData<> or TheoryDataRow<> provides a type-safe way to provide member data for theories. The compiler can indicate when you have provided incompatible data, and several other analyzers will help ensure your TheoryData<> or TheoryDataRow<> type usage matches your test method parameters.

How to fix violations

To fix a violation of this rule in v2, replace IEnumerable<object[]> with TheoryData<>.

To fix a violation of this rule in v3, replace IEnumerable<object[]>, IEnumerable<ITheoryDataRow>, or IEnumerable<TheoryDataRow> with either TheoryData<> or IEnumerable<TheoryDataRow<>>. You may also use IAsyncEnumerable<>, and you may wrap the return value in either Task<> or ValueTask<>.

Examples

Violates

For v2 and v3

using System.Collections.Generic;
using Xunit;

public class xUnit1042
{
    public static IEnumerable<object[]> TestData = new[] { new object[] { 42 }, new object[] { 2112 } };

    [Theory]
    [MemberData(nameof(TestData))]
    public static void TestMethod(int _)
    { }
}

For v3 only

using System.Collections.Generic;
using Xunit;

public class xUnit1042
{
    public static IEnumerable<TheoryDataRow> TestData = [new(42), new(2112)];

    [Theory]
    [MemberData(nameof(TestData))]
    public static void TestMethod(int _)
    { }
}

Does not violate

For v2 and v3

using Xunit;

public class xUnit1042
{
    public static TheoryData<int> TestData = new() { 42, 2112 };

    [Theory]
    [MemberData(nameof(TestData))]
    public static void TestMethod(int _)
    { }
}

For v3

using System.Collections.Generic;
using Xunit;

public class xUnit1042
{
    public static IEnumerable<TheoryDataRow<int>> TestData = [new(42), new(2112)];

    [Theory]
    [MemberData(nameof(TestData))]
    public static void TestMethod(int _)
    { }
}