v2
v3
Error
xUnit1039
"The type argument to theory data is not compatible with the type of the corresponding test method parameter"
Cause
The type argument given to TheoryData
or TheoryDataRow
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 theory data compatible.
Examples
Violates
Using TheoryData<>
(for v2 and v3)
using Xunit;
public class xUnit1039
{
public static TheoryData<int> PropertyData =>
new() { 1, 2, 3 };
[Theory]
[MemberData(nameof(PropertyData))]
public void TestMethod(string _) { }
}
Using TheoryDataRow<>
(for v3 only)
using System.Collections.Generic;
using Xunit;
public class xUnit1039
{
public static IEnumerable<TheoryDataRow<int>> PropertyData =>
[new(1), new(2), new(3)];
[Theory]
[MemberData(nameof(PropertyData))]
public void TestMethod(string _) { }
}
using System.Collections;
using System.Collections.Generic;
using Xunit;
public class ClassRowData : IEnumerable<TheoryDataRow<int>>
{
public IEnumerator<TheoryDataRow<int>> GetEnumerator()
{
yield return new(1);
yield return new(2);
yield return new(3);
}
IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
}
public class xUnit1039
{
[Theory]
[ClassData(typeof(ClassRowData))]
public void TestMethod(string _) { }
}
Does not violate
Using TheoryData<>
(for v2 and v3)
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 _) { }
}
Using TheoryDataRow<>
(for v3 only)
using System.Collections.Generic;
using Xunit;
public class xUnit1039
{
public static IEnumerable<TheoryDataRow<int>> PropertyData =>
[new(1), new(2), new(3)];
[Theory]
[MemberData(nameof(PropertyData))]
public void TestMethod(int _) { }
}
using System.Collections.Generic;
using Xunit;
public class xUnit1039
{
public static IEnumerable<TheoryDataRow<string>> PropertyData =>
[new("1"), new("2"), new("3")];
[Theory]
[MemberData(nameof(PropertyData))]
public void TestMethod(string _) { }
}
using System.Collections;
using System.Collections.Generic;
using Xunit;
public class ClassRowData : IEnumerable<TheoryDataRow<int>>
{
public IEnumerator<TheoryDataRow<int>> GetEnumerator()
{
yield return new(1);
yield return new(2);
yield return new(3);
}
IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
}
public class xUnit1039
{
[Theory]
[ClassData(typeof(ClassRowData))]
public void TestMethod(int _) { }
}
using System.Collections;
using System.Collections.Generic;
using Xunit;
public class ClassRowData : IEnumerable<TheoryDataRow<string>>
{
public IEnumerator<TheoryDataRow<string>> GetEnumerator()
{
yield return new("1");
yield return new("2");
yield return new("3");
}
IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
}
public class xUnit1039
{
[Theory]
[ClassData(typeof(ClassRowData))]
public void TestMethod(string _) { }
}