TUNU0001 code fixer does not remove 'using NUnit.Framework;' directive

[thomhurst]

Description

The TUNU0001 NUnit migration code fixer converts NUnit attributes to TUnit attributes, but does not remove the using NUnit.Framework; directive. This results in CS0246 errors after migration because the NUnit package is typically removed.

Reproduction Steps

1. Create a test file with NUnit:

using NUnit.Framework;

[TestFixture]
public class MyTests
{
    [Test]
    public void TestMethod()
    {
        Assert.AreEqual(1, 1);
    }
}

2. Run the TUNU0001 code fixer:

dotnet format analyzers --severity info --diagnostics TUNU0001 --framework net10.0

3. Remove the NUnit package:

dotnet remove package NUnit
dotnet remove package NUnit3TestAdapter

4. Build the project

Expected Behavior

The code fixer should remove the using NUnit.Framework; directive along with converting the attributes.

Actual Behavior

The using NUnit.Framework; directive remains, causing CS0246 errors:

error CS0246: The type or namespace name 'NUnit' could not be found

Workaround

Manually remove all using NUnit.Framework; directives:

find . -name "*.cs" -exec sed -i '/using NUnit\.Framework;/d' {} \;

Environment

• TUnit version: 1.11.64
• .NET SDK: 10.0.102

Tests should be added to verify the code fixer removes NUnit using directives.

[claude]

This appears to be related to several previously closed issues:

• TUNU0001 code fixer doesn't remove 'using NUnit.Framework;' directive #4422 - TUNU0001 code fixer doesn't remove 'using NUnit.Framework;' directive (closed 2026-01-15)
• TUNU0001 code fixer does not convert using NUnit.Framework to TUnit usings #4466 - TUNU0001 code fixer does not convert using NUnit.Framework to TUnit usings (closed 2026-01-17, just hours ago)
• NUnit Migration: using NUnit.Framework; statements not removed #4337 - NUnit Migration: using NUnit.Framework; statements not removed (closed 2026-01-13)
• NUnit Migration Code Fixer: Does not remove 'using NUnit.Framework;' directive #4386 - NUnit Migration Code Fixer: Does not remove 'using NUnit.Framework;' directive (closed 2026-01-14)

Since #4466 was very recently closed, this could be:

1. A regression if the fix was incomplete
2. A duplicate if the issue wasn't fully resolved
3. A different scenario not covered by the previous fix

@thomhurst Could you verify if this is the same issue as #4466 or if there's a specific case this highlights that wasn't covered?