xUnit1039 Error

The type argument to TheoryData is not compatible with the type of the corresponding test method parameter

Cause

The type argument given to TheoryData is not compatible with the matching parameter in the test method.

Reason for rule

When the data types aren’t compatible, then the test will fail at runtime with a type mismatch, instead of running the test.

How to fix violations

To fix a violation of this rule, make the types in the parameter and TheoryData compatible.

Examples

Violates

using Xunit;

public class xUnit1039
{
    public static TheoryData<int> PropertyData =>
        new() { 1, 2, 3 };

    [Theory]
    [MemberData(nameof(PropertyData))]
    public void TestMethod(string _) { }
}

Does not violate

using Xunit;

public class xUnit1039
{
    public static TheoryData<int> PropertyData =>
        new() { 1, 2, 3 };

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

using Xunit;

public class xUnit1039
{
    public static TheoryData<string> PropertyData =>
        new() { "1", "2", "3" };

    [Theory]
    [MemberData(nameof(PropertyData))]
    public void TestMethod(string _) { }
}