Fix findGlobalJsonFile boundary check for custom checkout paths (#21989)

[rishabhmalikMS]

Context

Fixes #21989

Regression introduced in v2.271 by PR #21892 ("fix global.json lookup at repository root"). Users running dotnet test with
Microsoft Testing Platform (MTP) and .slnx files get failures when using custom checkout paths (e.g., checkout: self with path:
in multi-repo pipelines).

---

Task Name

DotNetCoreCLIV2

---

Description

findGlobalJsonFile() uses Build.SourcesDirectory as the upper boundary when walking up from workingDirectory to find
global.json. With custom checkout paths (multi-repo checkout or checkout: self with path:), workingDirectory can resolve
outside Build.SourcesDirectory, causing the function to return null. This makes MTP detection fail, so the --solution flag is
not added to dotnet test, which newer .NET SDKs require for MTP projects.

Fix: Add a fallback chain for the search boundary:

1. Build.SourcesDirectory (default — works for standard checkout)
2. System.DefaultWorkingDirectory (covers single-checkout with custom path)
3. Agent.BuildDirectory (covers multi-repo checkout where both above stay at /s)

---

Risk Assessment (Low)

• The fix only changes behavior when workingDirectory is already outside Build.SourcesDirectory (currently broken — returns
  null). No change to existing working scenarios.
• Fallback boundaries are progressively wider but all scoped to the pipeline's build directory.
• All 50 existing unit tests pass unchanged.

---

Change Behind Feature Flag (No)

This is a bug fix for a regression. The current behavior (returning null when workingDirectory is outside SourcesDirectory) is
always wrong — there is no scenario where the broken behavior is desirable. A feature flag would leave affected users broken.

---

Tech Design / Approach

• findGlobalJsonFile() boundary check now tries three well-known pipeline variables in order: Build.SourcesDirectory →
  System.DefaultWorkingDirectory → Agent.BuildDirectory
• Each is progressively wider but still scoped to the current build
• The bottom-up search logic (while loop walking up directories) is unchanged
• Agent.BuildDirectory is the tightest safe boundary that covers all possible checkout locations

---

Documentation Changes Required (No)

No user-facing documentation changes needed. The fix restores expected behavior.

---

Unit Tests Added or Updated (Yes)

• New test: runTestsWithWorkingDirOutsideSourcesDir.ts — simulates the exact multi-repo checkout scenario from issue [BUG]: Solution Flag "--solution" is missing in DotNetCoreCLI #21989
  with Build.SourcesDirectory, System.DefaultWorkingDirectory, and Agent.BuildDirectory all set to different values
• Updated: L0.ts — added test case verifying Agent.BuildDirectory fallback is used, global.json is found, and --solution
  flag is added
• All 50 tests pass (49 existing + 1 new)

---

Additional Testing Performed

• Pipeline repro with multi-repo checkout (checkout: self with path: repository + second repo) on Azure DevOps hosted agent:
  • Original DotNetCoreCLI@2 v2.271: confirmed bug — global.json not found, no --solution flag
  • Fixed task v2.273: Agent.BuildDirectory fallback used, global.json found, --solution added
  • Verified with user-provided debug logs matching the exact failure pattern
  • pipeline link: https://dev.azure.com/rishabhmalikOrg/Test%20Project/_build/results?buildId=2472&view=logs&j=12f1170f-54f2-53f3-20dd-22fc7dff55f9&t=b801fef0-4998-5417-6df0-af092da60315

---

Logging Added/Updated (Yes)

• Debug messages added for each fallback step (which boundary was used and why)
• No sensitive data exposed
• Uses tl.debug() consistent with existing logging

---

Telemetry Added/Updated (No)

No new telemetry needed — this is a boundary check fix in an existing function.

---

Rollback Scenario and Process (Yes)

Rollback: revert this commit. The change is isolated to findGlobalJsonFile() in dotnetcore.ts. Version bump to 2.273.0 allows
pinning to previous version if needed.

---

Dependency Impact Assessed and Regression Tested (Yes)

• No new dependencies added
• All 50 unit tests pass
• Only dotnetcore.ts modified (task logic), no changes to shared packages

---

Checklist

• Related issue linked ([BUG]: Solution Flag "--solution" is missing in DotNetCoreCLI #21989)
• Task version was bumped (2.271.0 → 2.273.0)
• Verified the task behaves as expected

[rishabhmalikMS]

/azp run

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[rishabhmalikMS]

/azp run

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[rishabhmalikMS]

/azp run

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[rishabhmalikMS]

/azp run

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[rishabhmalikMS]

/azp run

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[dassayantan24]

.

[dassayantan24]

I think we can have single reporoot and no fallback

    private findGlobalJsonFile(): string | null {
     const boundary = path.resolve(
         tl.getVariable('Agent.BuildDirectory') || process.cwd()
     );
     let searchDir = path.resolve(this.workingDirectory || process.cwd());

     while (true) {
         const candidate = path.join(searchDir, 'global.json');
         if (tl.exist(candidate)) return candidate;

         const parentDir = path.dirname(searchDir);
         if (parentDir === searchDir) break;

         const rel = path.relative(boundary, parentDir);
         if (rel.startsWith('..') || path.isAbsolute(rel)) break;

         searchDir = parentDir;
     }
     return null;
 }