Migrate WriteCodeFragment task to use TaskEnvironment API by Copilot · Pull Request #13169 · dotnet/msbuild

Copilot · 2026-02-02T11:42:38Z

Context

Thread-safe tasks must avoid global process state (working directory, environment variables). WriteCodeFragment uses relative paths resolved against the current working directory, making it unsafe for multithreaded execution.

Changes Made

Add [MSBuildMultiThreadableTask] attribute and implement IMultiThreadableTask
Use TaskEnvironment.GetAbsolutePath() to resolve paths before file operations:
```
outputFilePath = TaskEnvironment.GetAbsolutePath(OutputFile.ItemSpec);
```
Pass absolute paths to FileUtilities.GetTemporaryFile(), FileUtilities.EnsureDirectoryExists(), File.WriteAllText(), and LockCheck.GetLockedFileMessage()
Update all test instantiations to set TaskEnvironment = TaskEnvironmentHelper.CreateForTest()
Preserve behavior: when OutputDirectory is relative and OutputFile is not specified, the resulting OutputFile output remains relative (matching original behavior)

Testing

All 52 WriteCodeFragment tests pass, including:

A new test RelativeOutputDirectoryProducesRelativeOutputFile that verifies when OutputDirectory is relative and OutputFile is not passed, the resulting OutputFile is also relative
The CommentIsInvariantCulture tests (added in main) now have TaskEnvironment initialized

Notes

None.

Original prompt

Migrate the WriteCodeFragment task to use TaskEnvironment API.
Make sure to preserve correctness, performance and that the tests pass

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

dotnet-policy-service · 2026-02-02T11:42:57Z

Hello @@copilot, I noticed that you’re changing an .swr file or any file under src/Package/MSBuild.VSSetup.. Please make sure to validate this change by an experimental VS insertion. This is accomplished by pushing to an exp/* branch, which requires write permissions to this repo.

Co-authored-by: JanProvaznik <25267098+JanProvaznik@users.noreply.github.com>

JanProvaznik

@copilot

src/Tasks/WriteCodeFragment.cs

Co-authored-by: JanProvaznik <25267098+JanProvaznik@users.noreply.github.com>

Copilot

Pull request overview

Migrates WriteCodeFragment to the TaskEnvironment API so relative paths are resolved against the project directory (not process current directory), enabling thread-safe execution in multithreaded MSBuild mode.

Changes:

Mark WriteCodeFragment as thread-safe ([MSBuildMultiThreadableTask]) and implement IMultiThreadableTask with a TaskEnvironment property.
Resolve output paths via TaskEnvironment.GetAbsolutePath() and use the resolved absolute path for directory creation, file writes, and lock diagnostics.
Update WriteCodeFragment unit tests to initialize TaskEnvironment via TaskEnvironmentHelper.CreateForTest().

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/Tasks/WriteCodeFragment.cs	Adds multithreadable task support and uses `TaskEnvironment` to resolve paths before I/O.
src/Tasks.UnitTests/WriteCodeFragment_Tests.cs	Updates tests to set `TaskEnvironment` on task instances.

src/Tasks/WriteCodeFragment.cs

src/Tasks.UnitTests/WriteCodeFragment_Tests.cs

Co-authored-by: JanProvaznik <25267098+JanProvaznik@users.noreply.github.com>

src/Tasks/WriteCodeFragment.cs

Co-authored-by: Rainer Sigwald <raines@microsoft.com>

JanProvaznik · 2026-02-06T16:00:29Z

@copilot create a test for the case when OutputDirectory is relative, OutputFile is not passed in that in that case we receive a relative OutputFile

Co-authored-by: JanProvaznik <25267098+JanProvaznik@users.noreply.github.com>

Copilot · 2026-02-06T16:05:39Z

@copilot create a test for the case when OutputDirectory is relative, OutputFile is not passed in that in that case we receive a relative OutputFile

Added test RelativeOutputDirectoryProducesRelativeOutputFile in fba0cca. The test verifies that when OutputDirectory is relative and OutputFile is not passed, the resulting OutputFile is also relative.

JanProvaznik · 2026-02-09T09:24:01Z

@copilot
System.NullReferenceException : Object reference not set to an instance of an object.

Stack trace
at Microsoft.Build.Tasks.WriteCodeFragment.Execute() in /_/src/Tasks/WriteCodeFragment.cs:line 124
at Microsoft.Build.UnitTests.WriteCodeFragment_Tests.CommentIsInvariantCulture(String cultureName) in D:\a\1\s\src\Tasks.UnitTests\WriteCodeFragment_Tests.cs:line 1306

…codefragment-task

Co-authored-by: JanProvaznik <25267098+JanProvaznik@users.noreply.github.com>

Copilot · 2026-02-09T09:29:27Z

@copilot
System.NullReferenceException : Object reference not set to an instance of an object.

...

Fixed in 5e4d0d4. The CommentIsInvariantCulture test from main was missing TaskEnvironment = TaskEnvironmentHelper.CreateForTest(). After merging main and adding the required TaskEnvironment initialization, all 52 WriteCodeFragment tests now pass.

### Context Thread-safe tasks must avoid global process state (working directory, environment variables). `WriteCodeFragment` uses relative paths resolved against the current working directory, making it unsafe for multithreaded execution. ### Changes Made - Add `[MSBuildMultiThreadableTask]` attribute and implement `IMultiThreadableTask` - Use `TaskEnvironment.GetAbsolutePath()` to resolve paths before file operations: ```csharp outputFilePath = TaskEnvironment.GetAbsolutePath(OutputFile.ItemSpec); ``` - Pass absolute paths to `FileUtilities.GetTemporaryFile()`, `FileUtilities.EnsureDirectoryExists()`, `File.WriteAllText()`, and `LockCheck.GetLockedFileMessage()` - Update all test instantiations to set `TaskEnvironment = TaskEnvironmentHelper.CreateForTest()` - Preserve behavior: when `OutputDirectory` is relative and `OutputFile` is not specified, the resulting `OutputFile` output remains relative (matching original behavior) ### Testing All 52 WriteCodeFragment tests pass, including: - A new test `RelativeOutputDirectoryProducesRelativeOutputFile` that verifies when `OutputDirectory` is relative and `OutputFile` is not passed, the resulting `OutputFile` is also relative - The `CommentIsInvariantCulture` tests (added in main) now have `TaskEnvironment` initialized ### Notes None.   <details> <summary>Original prompt</summary> > Migrate the WriteCodeFragment task to use TaskEnvironment API. > Make sure to preserve correctness, performance and that the tests pass </details>  --- ✨ Let Copilot coding agent [set things up for you](https://github.com/dotnet/msbuild/issues/new?title=✨+Set+up+Copilot+instructions&body=Configure%20instructions%20for%20this%20repository%20as%20documented%20in%20%5BBest%20practices%20for%20Copilot%20coding%20agent%20in%20your%20repository%5D%28https://gh.io/copilot-coding-agent-tips%29%2E%0A%0A%3COnboard%20this%20repo%3E&assignees=copilot) — coding agent works faster and does higher quality work when set up for your repo. --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: Jan Provazník <janprovaznik@microsoft.com>

Initial plan

0db6775

Copilot AI assigned Copilot and JanProvaznik Feb 2, 2026

Copilot started work on behalf of JanProvaznik February 2, 2026 11:42 View session

Migrate WriteCodeFragment task to use TaskEnvironment API

a68aff3

Co-authored-by: JanProvaznik <25267098+JanProvaznik@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Migrate WriteCodeFragment task to use TaskEnvironment API~~ Migrate WriteCodeFragment task to use TaskEnvironment API Feb 2, 2026

Copilot AI requested a review from JanProvaznik February 2, 2026 11:54

Copilot finished work on behalf of JanProvaznik February 2, 2026 11:54

JanProvaznik requested changes Feb 4, 2026

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src/Tasks/WriteCodeFragment.cs Outdated Show resolved Hide resolved

Copilot started work on behalf of JanProvaznik February 4, 2026 14:08 View session

Address review feedback: remove NormalizePath and .Value accesses

016d864

Co-authored-by: JanProvaznik <25267098+JanProvaznik@users.noreply.github.com>

Copilot AI requested a review from JanProvaznik February 4, 2026 14:13

Copilot finished work on behalf of JanProvaznik February 4, 2026 14:13

JanProvaznik approved these changes Feb 4, 2026

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JanProvaznik marked this pull request as ready for review February 4, 2026 16:19

Copilot AI review requested due to automatic review settings February 4, 2026 16:19

Copilot started reviewing on behalf of JanProvaznik February 4, 2026 16:19 View session

Copilot AI reviewed Feb 4, 2026

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Copilot started work on behalf of JanProvaznik February 5, 2026 11:15 View session

Remove ignoreRootedCheck from AbsolutePath constructor

2f2bcf3

Co-authored-by: JanProvaznik <25267098+JanProvaznik@users.noreply.github.com>

Copilot AI requested a review from JanProvaznik February 5, 2026 11:20

Copilot finished work on behalf of JanProvaznik February 5, 2026 11:20

JanProvaznik approved these changes Feb 5, 2026

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AR-May reviewed Feb 6, 2026

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rainersigwald approved these changes Feb 6, 2026

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JanProvaznik and others added 2 commits February 6, 2026 16:56

fix relative path directory edge case

a432986

Update src/Tasks/WriteCodeFragment.cs

af34a81

Co-authored-by: Rainer Sigwald <raines@microsoft.com>

Copilot started work on behalf of JanProvaznik February 6, 2026 16:00 View session

Add test for relative OutputDirectory producing relative OutputFile

fba0cca

Co-authored-by: JanProvaznik <25267098+JanProvaznik@users.noreply.github.com>

Copilot AI requested a review from JanProvaznik February 6, 2026 16:06

Copilot finished work on behalf of JanProvaznik February 6, 2026 16:06

JanProvaznik approved these changes Feb 6, 2026

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AR-May approved these changes Feb 9, 2026

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Copilot started work on behalf of JanProvaznik February 9, 2026 09:24 View session

Copilot AI and others added 2 commits February 9, 2026 09:25

Merge remote-tracking branch 'origin/main' into copilot/migrate-write…

70ced3d

…codefragment-task

Merge main and add TaskEnvironment to CommentIsInvariantCulture test

5e4d0d4

Co-authored-by: JanProvaznik <25267098+JanProvaznik@users.noreply.github.com>

Copilot finished work on behalf of JanProvaznik February 9, 2026 09:30

Copilot AI requested a review from JanProvaznik February 9, 2026 09:30

JanProvaznik enabled auto-merge (squash) February 9, 2026 09:32

JanProvaznik disabled auto-merge February 9, 2026 09:32

JanProvaznik enabled auto-merge (squash) February 9, 2026 09:32

JanProvaznik merged commit f3a5f8b into main Feb 9, 2026
10 checks passed

JanProvaznik deleted the copilot/migrate-writecodefragment-task branch February 9, 2026 10:20

This was referenced Feb 10, 2026

[main] Source code updates from dotnet/msbuild dotnet/dotnet#4746

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[main] Source code updates from dotnet/msbuild dotnet/dotnet#4835

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dotnet-maestro bot mentioned this pull request Mar 3, 2026

[release/10.0.3xx] Source code updates from dotnet/msbuild dotnet/dotnet#5204

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Migrate WriteCodeFragment task to use TaskEnvironment API#13169

Migrate WriteCodeFragment task to use TaskEnvironment API#13169
JanProvaznik merged 9 commits intomainfrom
copilot/migrate-writecodefragment-task

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