Fix TUnitAssertions0009 code fix for xUnit Assert.True/False with user message

[Copilot]

• Explore the repository and understand the issue
• Identify root cause: In XUnitAssertionCodeFixProvider.cs, for True/False cases, the code uses actual variable which incorrectly takes the userMessage as the 2nd argument instead of using expected (the condition as 1st argument)
• Fix the True and False cases in GetNewExpression method to:
  1. Use the first argument (condition) in Assert.That()
  2. Append .Because(userMessage) when a user message is provided
• Fix the True and False cases in ConvertLambdaBodyToTUnitAssertions method for consistent handling
• Add tests to verify the fix for both True and False with and without user messages
• Run tests to validate the fix
• Run code review (no issues found)
• Fix Fail and Skip assertions which were also broken (producing Fail.Test() instead of Fail.Test(message))
• Add tests for Fail and Skip with messages
• All 13 tests passing on net8.0 and net9.0

Original prompt

---

This section details on the original issue you should resolve

<issue_title>TUnitAssertions0009 invalid fix for xUnit.net's Assert.True and Assert.False with user message</issue_title>
<issue_description>Hello,

The analyzer fix for true/false assertion with a user message is not correct:

Xunit.Assert.True(condition, userMessage)
Xunit.Assert.False(condition, userMessage)

e.g.:

public class TrueFalseTest
{
    [Test]
    public void TrueTest()
    {
        bool result = true;
        Xunit.Assert.True(result, "user message if false");
    }

    [Test]
    public void FalseTest()
    {
        bool result = true;
        Xunit.Assert.False(result, "user message if false");
    }
}

Actual behavior

public class TrueFalseTest
{
    [Test]
    public void TrueTest()
    {
        bool result = true;
        Assert.That("user message if false").IsTrue();
    }

    [Test]
    public void FalseTest()
    {
        bool result = false;
        Assert.That("user message if false").IsFalse();
    }
}

Expected behavior

public class TrueFalseTest
{
    [Test]
    public void TrueTest()
    {
        bool result = true;
        Assert.That(result).IsTrue().Because("user message if false");
    }

    [Test]
    public void FalseTest()
    {
        bool result = false;
        Assert.That(result).IsFalse().Because("user message if true");
    }
}

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes TUnitAssertions0009 invalid fix for xUnit.net's Assert.True and Assert.False with user message #3857

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[thomhurst]

@copilot Do any other assertions need special handling for messages?

[Copilot]

@copilot Do any other assertions need special handling for messages?

Yes, good catch! I found that Fail and Skip were also broken - they were generating Fail.Test() and Skip.Test() without the required message/reason argument.

Fixed in commit 0f5ab0a:

• Assert.Fail("message") → Fail.Test("message")
• Assert.Skip("reason") → Skip.Test("reason")

The other xUnit assertions (Equal, NotEqual, Null, NotNull, Contains, Same, NotSame, Empty, NotEmpty, IsType, Throws, etc.) don't have user message overloads in xUnit's API.

[Copilot]

Pull request overview

This PR fixes the TUnitAssertions0009 code fix provider that was incorrectly converting xUnit's Assert.True/Assert.False assertions when a user message was provided. The fix also addresses similar issues with Assert.Fail and Assert.Skip assertions.

Key Changes:

• Fixed True/False assertions to use the condition (first argument) instead of the message (second argument) as the assertion subject
• Added proper .Because(message) suffix when user messages are provided
• Fixed Fail/Skip assertions to include the message parameter in the generated code

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
TUnit.Assertions.Analyzers.CodeFixers/XUnitAssertionCodeFixProvider.cs	Fixed True/False/Fail/Skip code fix logic in GetNewExpression method; added CreateBooleanAssertion helper; enhanced ConvertLambdaBodyToTUnitAssertions to handle messages
TUnit.Assertions.Analyzers.CodeFixers.Tests/XUnitAssertionCodeFixProviderTests.cs	Added 6 comprehensive test cases covering True/False/Fail/Skip with and without messages