docs: update method-data-source.md example to not use `func<..>`

[jacob7395]

Update the docs for docs/docs/tutorial-basics/method-data-source.md to build/work by removing the func<..> syntax.

Maybe it's overkill but could have these example as part of the test suit, then use a build action to copy them into files referenced in the docs?

Not needed for this but could help prevent the issue in future.

[jacob7395]

I probably should have read the docs first dose this no longer apply;

If methods are returning reference types, they should return a `Func<T>` rather than just a `T` - This ensures each test has its own instance of that object and tests aren't sharing objects which could lead to unintended side effects.

I tried the example bellow and everything is fine;

public class AdditionTestData
{
    public int Value1 { get; }
    public int Value2 { get; }
    public int ExpectedResult { get; }

    public AdditionTestData(int value1, int value2, int expectedResult)
    {
        Value1 = value1;
        Value2 = value2;
        ExpectedResult = expectedResult;
    }
}

public static class MyTestDataSources
{
    public static AdditionTestData AdditionTestData()
    {
        return new AdditionTestData(1, 2, 3);
    }
}

public class MyTestClass
{
    [Test]
    [MethodDataSource(typeof(MyTestDataSources), nameof(MyTestDataSources.AdditionTestData))]
    public async Task MyTest(AdditionTestData additionTestData)
    {
        var result = Add(additionTestData.Value1, additionTestData.Value2);

        await Assert.That(result).IsEqualTo(additionTestData.ExpectedResult);
    }

    private int Add(int x, int y)
    {
        return x + y;
    }
}

Are there some types this is still required for? and in those cases should your method take Func like bellow;

public class AdditionTestData
{
    public int Value1 { get; }
    public int Value2 { get; }
    public int ExpectedResult { get; }

    public AdditionTestData(int value1, int value2, int expectedResult)
    {
        Value1 = value1;
        Value2 = value2;
        ExpectedResult = expectedResult;
    }
}

public static class MyTestDataSources
{
    public static IEnumerable<Func<AdditionTestData>> AdditionTestData()
    {
        yield return () => new AdditionTestData(1, 2, 3);
    }
}

public class MyTestClass
{
    [Test]
    [MethodDataSource(typeof(MyTestDataSources), nameof(MyTestDataSources.AdditionTestData))]
    public async Task MyTest(Func<AdditionTestData> testDataBuilder)
    {
        var additionTestData = testDataBuilder.Invoke();

        var result = Add(additionTestData.Value1, additionTestData.Value2);

        await Assert.That(result).IsEqualTo(additionTestData.ExpectedResult);
    }

    private int Add(int x, int y)
    {
        return x + y;
    }
}
```.

[jacob7395]

Reading it again I guess this is to trying to prevent tests modifying a shared reference (just do immutability bro), in this case is the MethodDataSource no longer supporting func<..> a bug, if you try one of the example in the current docs it give's a build error.

[thomhurst]

in this case is the MethodDataSource no longer supporting func<..> a bug, if you try one of the example in the current docs it give's a build error.

Which example?

[jacob7395]

I am missing something, maybe I did encounter an issue since there are tests for this in TUnit.TestProject and although I get errors before building it builds fine.

[jacob7395]

in this case is the MethodDataSource no longer supporting func<..> a bug, if you try one of the example in the current docs it give's a build error.

Which example?

When I copy any of the example into Rider I get the bellow error in my IDE, but they run and build fine?

[jacob7395]

Okay, I think the issue I was getting was due to my main project being out of date.

I was trying to replicate the issue in an example project when I get the above error that threw me off. Updating my package solved the build error on my main project.

[thomhurst]

I've found sometimes updating packed with analyzers requires restarting the ide to reload the analyzers with the new logic

[jacob7395]

Will close this as this wasn't an issue, the IDE error shown above goes away once the test is run. Maybe something to look into but I am guessing just something to do with how the tests are generated.