v2 v3   Info

xUnit1044

"Avoid using TheoryData type arguments that are not serializable"

Cause

A violation of this rule occurs when a type in the generic TheoryData<> is known to not be serializable.

Reason for rule

Non-serializable data makes it impossible for the developer to run individual data rows inside of Visual Studio's Test Explorer.

How to fix violations

To fix a violation of this rule, use data that is known to be serializable. This includes all the supported built-in types (listed below) or any type which implements IXunitSerializable, as well as arrays of any supported type and nullable versions of any supported value type.

Supported built-in types (as of v2 2.7.1 and v3 0.1.1-pre.392) include:

• BigInteger
• bool
• byte and sbyte
• char
• DateTime, DateTimeOffset, and TimeSpan
• DateOnly and TimeOnly (.NET 8+ only)
• Enum values (unless you're using .NET Framework and they live in the GAC)
• decimal
• float and double
• int and uint
• long and ulong
• short and ushort
• string
• Type

Additional built-in types supported for v3 (as of 0.5.0) include:

• Guid
• Index and Range (.NET 8+ only)
• Uri
• Version

Examples

Violates

using Xunit;

public sealed class TestData { }

public class TestClass
{
    public static TheoryData<TestData> DataSource = [];

    [Theory]
    [MemberData(nameof(DataSource))]
    public void TestMethod(TestData data) { }
}

Does not violate

using Xunit;

public class TestClass
{
    public static TheoryData<int, string> DataSource = [];

    [Theory]
    [MemberData(nameof(DataSource))]
    public void TestMethod(int intValue, string stringValue) { }
}

using Xunit;
using Xunit.Abstractions;  // for IXunitSerializable in v2
using Xunit.Sdk;           // for IXunitSerializable in v3

public sealed class TestData : IXunitSerializable { }

public class TestClass
{
    public static TheoryData<TestData> DataSource = [];

    [Theory]
    [MemberData(nameof(DataSource))]
    public void TestMethod(TestData data) { }
}