TUXU0001: Partial file conversion leaves project in broken mixed state

[thomhurst]

Description

When running the xUnit migration code fixer on a project with multiple test files, some files are converted while others are not. This leaves the project in a broken state where:

1. Some files have TUnit syntax ([Test], await Assert.That())
2. Other files still have xUnit syntax ([Fact], Assert.Equal())
3. Both xUnit and TUnit packages are referenced
4. Enabling TUnit implicit usings causes ambiguous reference errors in unconverted files
5. Disabling implicit usings causes missing type errors in converted files

Steps to Reproduce

1. Create a test project with 50+ xUnit test files
2. Add TUnit package reference
3. Run dotnet format analyzers --severity info --diagnostics TUXU0001
4. Observe partial conversion

Observed Behavior

In my test case with ~85 test files:

• ~54 files (~63%) were converted to TUnit syntax
• ~31 files (~37%) were NOT converted at all

The unconverted files still have:

• using Xunit;
• [Fact] attributes
• Assert.Equal(), Assert.True(), etc.

The Broken State

With TUnit Implicit Usings Enabled

<TUnitImplicitUsings>true</TUnitImplicitUsings>

Result:

• Converted files work but unconverted files fail:

error CS0104: 'Assert' is an ambiguous reference between 'TUnit.Assertions.Assert' and 'Xunit.Assert'

With TUnit Implicit Usings Disabled

<TUnitImplicitUsings>false</TUnitImplicitUsings>

Result:

• Unconverted files might work but converted files fail:

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

Expected Behavior

The code fixer should either:

1. Convert ALL files in a project when run in project/solution scope (Fix All)
2. Clearly report which files couldn't be converted and why
3. Not leave the project in a broken, inconsistent state

Impact

This partial conversion issue makes the migration process extremely difficult because:

1. Users cannot simply run the code fixer and have a working project
2. Manual intervention is required to fix hundreds/thousands of compilation errors
3. It's unclear which files need manual attention
4. The error messages don't indicate whether the issue is with xUnit remnants or TUnit migration

Suggested Fix

1. Priority: Fix the "Fix All" action (see issue TUXU0001: XUnitMigrationCodeFixProvider Fix All action not working #4416) so all files are converted
2. Add diagnostic output listing files that couldn't be converted
3. Add a validation pass after conversion that ensures no mixed state exists
4. Consider atomic conversion - either convert all files or roll back changes

Workaround (for users)

Until this is fixed, users must:

1. Run the code fixer
2. Manually identify unconverted files: grep -l "\[Fact\]" **/*.cs
3. Manually convert or run the code fixer file-by-file on remaining files
4. Or remove xUnit package and fix all errors manually

Environment

• TUnit Version: 1.11.*
• .NET SDK: 10.0.102
• OS: Windows

Related Issues

• TUXU0001: XUnitMigrationCodeFixProvider Fix All action not working #4416 - Fix All action not working
• TUXU0001: Code fixer does not remove 'using Xunit;' directive after conversion #4417 - using Xunit not removed after conversion

[claude]

Issue Analysis

Type: Bug Report - Critical Priority

Root Cause: This issue is a direct consequence of #4416 (Fix All action not working). The partial file conversion occurs because the XUnitMigrationCodeFixProvider doesn't implement GetFixAllProvider(), causing only some files to be processed during batch operations.

Impact Assessment:

• 🔴 Critical severity - Blocks the primary xUnit migration workflow
• 🔴 Leaves projects in a broken, non-compiling state
• 🔴 Scales badly with project size (31/85 files unconverted = ~37% manual work)
• 🔴 No clean automated workaround available

Related Issues Cluster:
This is part of a cluster of 5 TUXU0001 migration issues:

• TUXU0001: XUnitMigrationCodeFixProvider Fix All action not working #4416 - Fix All action not working (root cause)
• TUXU0001: Partial file conversion leaves project in broken mixed state #4420 - Partial conversion (this issue - consequence of TUXU0001: XUnitMigrationCodeFixProvider Fix All action not working #4416)
• TUXU0001: Code fixer does not remove 'using Xunit;' directive after conversion #4417 - using Xunit; not removed
• TUXU0001: Assert.Empty and Assert.Equal for collections convert to invalid TUnit assertions #4418 - Invalid collection assertions generated
• TUXU0001: Assert.Throws conversion loses ability to access exception properties (.Message, custom properties) #4419 - Assert.Throws conversion broken

Recommendation:
Fixing #4416 (implementing GetFixAllProvider()) should resolve the partial conversion problem described in this issue. Both issues should remain open to track the technical fix (#4416) and validate the user-facing impact is resolved (#4420).

Suggested Fix Priority Order:

1. Fix TUXU0001: XUnitMigrationCodeFixProvider Fix All action not working #4416 first (enables Fix All)
2. Validate TUXU0001: Partial file conversion leaves project in broken mixed state #4420 is resolved (all files convert)
3. Address TUXU0001: Code fixer does not remove 'using Xunit;' directive after conversion #4417, TUXU0001: Assert.Empty and Assert.Equal for collections convert to invalid TUnit assertions #4418, TUXU0001: Assert.Throws conversion loses ability to access exception properties (.Message, custom properties) #4419 (fix conversion quality issues)

[thomhurst]

This appears to be a duplicate of #4416 - both report that "Fix All" is not working.

Please see my investigation findings in #4416 for details on how Fix All is configured and troubleshooting steps.