Run .NET Tests

Purpose

Provide standardized instructions for running .NET 10 tests correctly. Ensures agents use the scripts/test-with-timeout.sh wrapper instead of direct dotnet test calls, which fail due to .NET 10's dual test runner architecture.

When to Use This Skill

• Before committing code changes that affect C# code
• When verifying bug fixes or new features
• When running targeted tests during development
• When the full test suite must pass before marking work complete

Hard Rules

Must

• ALWAYS use scripts/test-with-timeout.sh wrapper - never call dotnet test directly
• Run tests from the repository root (the wrapper handles directory changes automatically)
• Use --solution src/tfplan2md.slnx for full test suite runs
• Use --project with relative paths from src/ directory (e.g., --project tests/Oocx.TfPlan2Md.TUnit/)
• Wait for test completion and check exit code (0 = pass, non-zero = fail)
• For snapshot test changes, use the update-test-snapshots skill instead of manual edits

Must Not

• NEVER run dotnet test directly from command line - it will fail with MSB1001: Unknown switch errors from repo root
• Never manually edit snapshot files in src/tests/Oocx.TfPlan2Md.TUnit/TestData/Snapshots/ - use the update-test-snapshots skill
• Never ignore test failures or skip tests to make CI pass
• Never modify test expectations to match broken output - fix the code, not the tests

.NET 10 Dual Test Runner Issue

.NET 10 introduced two distinct test runners with incompatible CLI flags:

Working Directory	Runner Mode	--solution	--project	--treenode-filter	Result
Repo root (/)	VSTest	❌	❌	❌	MSBuild error MSB1001: Unknown switch
src/ (where global.json lives)	Microsoft.Testing.Platform	✅	✅	✅	Works correctly

The scripts/test-with-timeout.sh wrapper automatically:

1. Changes to the src/ directory (where global.json with "runner": "Microsoft.Testing.Platform" exists)
2. Normalizes any src/-prefixed paths in arguments
3. Enforces a timeout to prevent hung test runs (default 120 seconds)

Why direct dotnet test fails: Running from repo root activates VSTest mode (no global.json), which doesn't support --solution, --project, or --treenode-filter flags. The wrapper ensures tests run from src/ directory to activate Microsoft.Testing.Platform mode.

Common Test Commands

Run Full Test Suite

scripts/test-with-timeout.sh -- dotnet test --solution src/tfplan2md.slnx

Run Tests with Build

scripts/test-with-timeout.sh -- dotnet test --solution src/tfplan2md.slnx --configuration Release --verbosity normal

Run Tests Without Build (faster when already built)

scripts/test-with-timeout.sh -- dotnet test --solution src/tfplan2md.slnx --no-build

Override Timeout (for slow tests)

scripts/test-with-timeout.sh --timeout-seconds 300 -- dotnet test --solution src/tfplan2md.slnx

Run Specific Project Tests

scripts/test-with-timeout.sh -- dotnet test --project tests/Oocx.TfPlan2Md.TUnit/

TUnit Test Filtering

Important: This project uses TUnit (not xUnit). TUnit uses --treenode-filter instead of --filter. All TUnit-specific flags must come after -- in the wrapper command.

Filter by Class Name (hierarchical pattern)

scripts/test-with-timeout.sh -- dotnet test --project tests/Oocx.TfPlan2Md.TUnit/ --treenode-filter /*/*/MarkdownRendererTests/*

Filter by Test Method Name

scripts/test-with-timeout.sh -- dotnet test --project tests/Oocx.TfPlan2Md.TUnit/ --treenode-filter /*/*/*/Render_ValidPlan_ContainsSummarySection

Filter Pattern Explanation

TUnit uses hierarchical path patterns:

• /*/*/*/TestMethodName - Match specific test method
• /*/*/ClassName/* - Match all tests in a class
• /*/Namespace.ClassName/* - Match by namespace and class

Workflow Integration

When to Run Tests

1. During Development (after each meaningful change):

   # Run targeted tests for the area you modified
   scripts/test-with-timeout.sh -- dotnet test --project tests/Oocx.TfPlan2Md.TUnit/ --treenode-filter /*/*/YourTestClass/*
   

2. Before Committing (C# code changes only):

   # Run full test suite to ensure no regressions
   scripts/test-with-timeout.sh -- dotnet test --solution src/tfplan2md.slnx --no-build
   

3. Skip Tests When (documentation/agent instructions only):

   • Changes are limited to .github/agents/, .github/skills/, .github/copilot-instructions.md, or docs/
   • No C# code was modified
   • The test suite doesn't validate these file types

Handling Test Failures

1. Read the failure output - TUnit provides detailed error messages
2. Identify the failing test - Look for the test method name and class
3. Run the specific failing test - Use --treenode-filter to isolate it
4. Debug and fix - Fix the code (never modify test expectations unless the test itself is wrong)
5. Re-run tests - Verify the fix works
6. Run full suite - Ensure no regressions before committing

Snapshot Test Changes

If tests fail because snapshot files need updating (intentional output changes):

1. Use the update-test-snapshots skill - Never manually edit snapshot files
2. Verify the new output is correct - Review the diff carefully
3. Include SNAPSHOT_UPDATE_OK in commit message - Document the intentional change
4. Re-run tests - Confirm all tests pass with new snapshots

Exit Codes

Exit Code	Meaning	Action
0	All tests passed	Proceed with commit
1-123	Test failures	Fix failing tests before committing
124	Timeout	Increase timeout with --timeout-seconds or investigate hung tests
125	Wrapper error	Check command syntax

Golden Example

Complete workflow for implementing a feature:

# 1. Build the project
dotnet build

# 2. Run targeted tests during development
scripts/test-with-timeout.sh -- dotnet test --project tests/Oocx.TfPlan2Md.TUnit/ --treenode-filter /*/*/MyFeatureTests/*

# 3. Make changes, run tests again
scripts/test-with-timeout.sh -- dotnet test --project tests/Oocx.TfPlan2Md.TUnit/ --treenode-filter /*/*/MyFeatureTests/*

# 4. Before committing, run full suite
scripts/test-with-timeout.sh -- dotnet test --solution src/tfplan2md.slnx --no-build

# 5. If all pass, commit changes
git add .
git commit -m "feat: implement my feature"

Troubleshooting

Error: MSBuild error MSB1001: Unknown switch

Cause: Running dotnet test directly from repo root (VSTest mode doesn't support --solution/--project flags) Solution: Use scripts/test-with-timeout.sh wrapper

Error: Timeout after 120 seconds

Cause: Tests taking longer than default timeout Solution: Increase timeout with --timeout-seconds 300 (or higher)

Error: Test not found with --treenode-filter

Cause: Incorrect filter pattern or test doesn't exist Solution:

• List all tests first: scripts/test-with-timeout.sh -- dotnet test --list-tests
• Verify filter pattern matches TUnit hierarchical structure

Snapshot test failures after output changes

Cause: Intentional output format changes Solution: Use update-test-snapshots skill to regenerate snapshots correctly