xUnit1044 Info

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 6+ 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

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) { }
}