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Add support for static test classes - #174

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AArnott merged 5 commits into
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copilot/add-support-for-static-tests
Jan 28, 2026
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Add support for static test classes#174
AArnott merged 5 commits into
mainfrom
copilot/add-support-for-static-tests

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Copilot AI commented Jan 27, 2026 •
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Fix static test class support in Xunit.StaFact

Plan:

  • Explore repository and understand the issue
  • Identify the root cause: xUnit v3 calls .Single() on GetConstructors() for test class instantiation
  • Fix GetSettingsAttributes method in Utilities.cs to handle static test classes
  • Override CreateTestClassInstance in UITestRunner to handle static test classes
  • Add test cases for static test classes with UIFact, UITheory, StaFact, StaTheory attributes
  • Verify the fix works by running tests
  • Run code review
  • Run security scan
  • Fix all build warnings

Root Cause:

The issue was in xUnit v3's XunitTestRunnerBase.CreateTestClassInstance() method which calls GetConstructors().Single(). For static test classes, GetConstructors() returns an empty array, causing .Single() to throw "Sequence contains no elements".

Fix Applied:

  1. Refactored GetSettingsAttributes in Utilities.cs to use try-catch blocks around GetCustomAttributes calls with FirstOrDefault() instead of SingleOrDefault()
  2. Override CreateTestClassInstance in UITestRunner.cs to detect static test classes (Abstract + Sealed) and return null instance instead of trying to instantiate them
  3. Added comprehensive test coverage with 11 new tests covering:
    • Static UIFact tests (sync and async)
    • Static UITheory tests (sync and async)
    • Static StaFact tests
    • Static StaTheory tests
    • Static test classes with UISettings attributes (class-level and method-level)
  4. Fixed IDE0008 warning by using explicit Type instead of var for @Class variable

Test Results:

  • Total tests increased from 158 to 168 (10 new passing tests)
  • All static test class tests are passing (StaFact/StaTheory skip on non-Windows as expected)
  • No regressions in existing tests
  • Build: ✅ 0 warnings, 0 errors
  • Code Review: ✅ Passed
  • Security Scan: ✅ No vulnerabilities found

Security Summary:

No security vulnerabilities were introduced or discovered during this change. The CodeQL security scan found 0 alerts.

Original prompt

This section details on the original issue you should resolve

<issue_title>Does not work with static test class</issue_title>
<issue_description>Xunit.StaFact does not work with static test class. Here is a repro:

https://github.com/weifenluo/StaFactNotWorking

Running the test will produce the following error:

Message: 
System.InvalidOperationException : Sequence contains no elements

  Stack Trace: 
ThrowHelper.ThrowNoElementsException()
Enumerable.Single[TSource](IEnumerable`1 source)
--- End of stack trace from previous location ---
```</issue_description>

<agent_instructions>Add support for `static` test classes, and add a test to demonstrate that it works.</agent_instructions>

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

<comments>
<comment_new><author>@AArnott</author><body>
Thanks for the report and repro.
TBH I never understood why people bothered with `static` tests. But I have no objection to supporting that.</body></comment_new>
</comments>

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

Copilot AI and others added 3 commits January 27, 2026 17:11
@AArnott
Add try-catch for GetCustomAttributes to handle static test classes
6dcb3d8 
Changed GetSettingsAttributes to use try-catch blocks with FirstOrDefault
to handle cases where xUnit's GetCustomAttributes throws InvalidOperationException
for static test classes. Also added test cases for static test classes.

Co-authored-by: AArnott <3548+AArnott@users.noreply.github.com>
@AArnott
Override CreateTestClassInstance to support static test classes
7589ff4 
Added override in UITestRunner to handle static test classes by checking
if the class is both Abstract and Sealed (which indicates a static class).
For static classes, returns null instance instead of trying to instantiate.
Tests now pass for static test classes.

Co-authored-by: AArnott <3548+AArnott@users.noreply.github.com>
@AArnott
Fix trailing newline in StaticTestClassTests.cs
29f9a7e 
Co-authored-by: AArnott <3548+AArnott@users.noreply.github.com>
Copilot AI changed the title [WIP] Add support for static test classes in Xunit.StaFact Add support for static test classes Jan 27, 2026
Copilot AI requested a review from AArnott January 27, 2026 17:25
@AArnott
AArnott marked this pull request as ready for review January 27, 2026 19:37
@AArnott

AArnott commented Jan 27, 2026

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@copilot fix all build warnings. Use dotnet build -t:rebuild to ensure you see all warnings.

@AArnott
Fix IDE0008 warning by using explicit Type instead of var
49a99ad 
Changed var to Type for @Class variable in CreateTestClassInstance
to comply with project's editorconfig rule csharp_style_var_elsewhere = false:warning

Co-authored-by: AArnott <3548+AArnott@users.noreply.github.com>

Copilot AI commented Jan 27, 2026

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@copilot fix all build warnings. Use dotnet build -t:rebuild to ensure you see all warnings.

Fixed in commit 49a99ad. Changed var to explicit Type for the @Class variable to comply with the project's editorconfig rule csharp_style_var_elsewhere = false:warning. Build now succeeds with 0 warnings and 0 errors.

Copilot AI requested a review from AArnott January 27, 2026 20:01
@codecov-commenter

codecov-commenter commented Jan 28, 2026 •
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Codecov Report

❌ Patch coverage is 71.42857% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.52%. Comparing base (2c212b8) to head (49a99ad).

Files with missing lines Patch % Lines
src/Xunit.StaFact/Sdk/Utilities.cs 71.42% 4 Missing ⚠️
src/Xunit.StaFact/Sdk/UITestRunner.cs 71.42% 1 Missing and 1 partial ⚠️
Additional details and impacted files 
@@            Coverage Diff             @@
##             main     #174      +/-   ##
==========================================
- Coverage   71.60%   71.52%   -0.09%     
==========================================
  Files          36       36              
  Lines         729      748      +19     
  Branches       62       64       +2     
==========================================
+ Hits          522      535      +13     
- Misses        186      191       +5     
- Partials       21       22       +1
Flag Coverage Δ
Linux 71.16% <71.42%> (-0.09%) ⬇️
Windows 68.58% <71.42%> (-0.01%) ⬇️
macOS 71.16% <71.42%> (-0.09%) ⬇️

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@AArnott
AArnott merged commit 7555327 into main Jan 28, 2026
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@AArnott
AArnott deleted the copilot/add-support-for-static-tests branch January 28, 2026 04:00
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Does not work with static test class

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