Mutation Testing Baselines

Sprint: SPRINT_0353_0001_0001_mutation_testing_integration Task: MUT-0353-005

This document tracks mutation testing baselines for critical modules.

Baseline Scores

Module	Initial Score	Target Score	Date Established
Scanner.Core	72%	≥ 80%	2025-12-16
Policy.Engine	68%	≥ 80%	2025-12-16
Authority.Core	75%	≥ 85%	2025-12-16
Signer.Core	70%	≥ 80%	TBD
Attestor.Core	65%	≥ 80%	TBD
Reachability.Core	60%	≥ 75%	TBD

Threshold Configuration

See stryker-thresholds.json for per-module threshold configuration.

Mutation Operators Applied

Operator	Description	Enabled
Arithmetic	Replace +, -, *, /, %	✓
Boolean	Flip true/false	✓
Comparison	Replace <, >, <=, >=, ==, !=	✓
Logical	Replace &&,
String	Mutate string literals	✓
Linq	Mutate LINQ methods	✓
NullCoalescing	Mutate ?? operators	✓
Assignment	Mutate assignment operators	✓

Exclusions

The following patterns are excluded from mutation testing:

**/Migrations/** - Database migrations (tested via integration tests)
**/Generated/** - Generated code
**/*.g.cs - Source-generated files
**/Models/** - Simple data transfer objects
**/Exceptions/** - Exception types (tested via integration)

Running Mutation Tests

Local Execution

# Run mutation tests for a specific module
cd src/Scanner/__Libraries/StellaOps.Scanner.Core
dotnet stryker

# Run with specific configuration
dotnet stryker -f stryker-config.json --reporter html

# Quick mode (fewer mutations, faster feedback)
dotnet stryker --since:main

CI Execution

Mutation tests run on:

Merge requests targeting main
Weekly scheduled runs (comprehensive)

Results are uploaded as artifacts and published to the mutation testing dashboard.

Improving Mutation Score

Add missing test cases - Cover edge cases revealed by surviving mutants
Strengthen assertions - Replace weak assertions with specific ones
Test boundary conditions - Cover off-by-one and boundary scenarios
Add negative tests - Test that invalid inputs are rejected

2.4 KiB Raw Blame History