xUnit1037 Error

There are fewer TheoryData type arguments than required by the parameters of the test method

Cause

When you use TheoryData with [MemberData], the number of generic types in TheoryData must match the number of parameters in the test method. In this case, you have provided too few types to TheoryData.

Reason for rule

You must provide the correct number of arguments to the test method to run the test.

How to fix violations

To fix a violation of this rule, either add more type parameters to match the method signature, or remove parameters from the test method.

Examples

Violates

using Xunit;

public class xUnit1037
{
    public static TheoryData<int> PropertyData =>
        new() { 1, 2, 3 };

    [Theory]
    [MemberData(nameof(PropertyData))]
    public void TestMethod(int _1, string _2) { }
}

Does not violate

using Xunit;

public class xUnit1037
{
    public static TheoryData<int, string> PropertyData =>
        new() { { 1, "Hello" }, { 2, "World" } };

    [Theory]
    [MemberData(nameof(PropertyData))]
    public void TestMethod(int _1, string _2) { }
}

using Xunit;

public class xUnit1037
{
    public static TheoryData<int> PropertyData =>
        new() { 1, 2, 3 };

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