Multi-Language Code Quality & Test Coverage

Role

Senior SRE Engineer focused on quality, stability, and technical-debt reduction across multi-language codebases.

Goal

Perform a comprehensive intervention in the target repository to stabilize the build, reduce static-analysis warnings, raise test coverage to the language target, apply high-level architectural patterns, and produce a measured improvement report — without auto-opening a Pull Request.

When to Use

• A repository (.NET, Java, or Python) has accumulated warnings, smells, or suppressed exceptions.
• Test coverage is below the language target and needs a structured push.
• Technical debt must be reduced before a release or handoff.
• Security CVEs (NU1903, OWASP, Bandit, Safety, Snyk) must be cleared.

When NOT to use: one small file, a single change review, or a quick lint pass. For reviewing a single change, use code-review-and-quality.

• User asks or mentions this skill in English (e.g., "use /quality-test-implementation", "run quality-test-implementation").
• O usuário pede ou menciona esta skill em português (ex.: "use /quality-test-implementation", "execute quality-test-implementation").

Inputs

• REPO_NAME: full name (owner/repo).
• BASE_BRANCH: branch to start from (default main/develop).
• OUTPUT_BRANCH: feature/{YYYYMMDD}-{function-name}.
• PRIMARY_LANGUAGE: dotnet, java, or python.

---

Phase 1 — Preparation and Environment

1. Clone {REPO_NAME} if not already present.
2. Create working branch feature/{YYYYMMDD}-{function-name}.
3. Identify the build/test tooling:
   • .NET: *.sln, *.csproj, Directory.Build.props, global.json.
   • Java: pom.xml (Maven) or build.gradle* (Gradle).
   • Python: pyproject.toml, setup.py, requirements*.txt, tox.ini.
4. Keep any Environment.SetEnvironmentVariable("Testing", "true") (or equivalent) inside the test execution context only.

---

Phase 2 — Static Analysis and Warning Correction

Run the appropriate static-analysis tools and fix the following categories.

.NET

Category	Codes	Fix
Logging	CA2017, S2629, CA2254	Use static templates and consistent placeholders
Asynchronism	CS4014, CS1998	Add await or remove unnecessary async
Cleanup	CS0105, CS0219	Remove duplicate usings / unused variables
Exceptions	S3445, S2139	Replace throw ex; with throw;; add context on rethrow
Web/API	ASP0019	Use .Append in headers
Security	NU1903	Resolve package vulnerabilities (high priority)
Documentation	—	Add /// <summary> to public classes and methods

Tools: dotnet build, dotnet test, dotnet format, SonarScanner, Roslyn analyzers.

Java

Category	Codes / Tools	Fix
Logging	SLF4J placeholders, Checkstyle	Parameterized logging; avoid string concatenation in logs
Asynchronism	SpotBugs NP_NULL, Sonar S2190	Proper CompletableFuture chaining; avoid fire-and-forget async
Cleanup	PMD, Checkstyle	Remove unused imports and variables
Exceptions	Sonar S1166, S2221	Preserve stack trace; do not swallow exceptions
Web/API	Sonar S3751, S2658	Use correct header APIs; avoid mutable static state
Security	OWASP dependency-check, Snyk	Update vulnerable dependencies
Documentation	Javadoc	Add Javadoc to public classes and methods

Tools: mvn compile, mvn test, mvn spotbugs:spotbugs, mvn checkstyle:checkstyle, mvn org.owasp:dependency-check-maven:check.

Python

Category	Codes / Tools	Fix
Logging	Pylint W1203, Ruff G001	Use %/f-string formatting with logging correctly
Asynchronism	Pylint W0707, Ruff ASYNC	Use await properly; avoid asyncio fire-and-forget
Cleanup	F401, F841 (Ruff/Flake8)	Remove unused imports and variables
Exceptions	Pylint W0706, W0719	Re-raise with raise or raise Custom() with from
Web/API	Bandit B104	Avoid hard-coded * in CORS; validate headers
Security	Bandit, Safety, Snyk	Fix high/critical CVEs in requirements.txt / pyproject.toml
Documentation	Pydocstyle, Ruff D	Add docstrings to public classes and methods

Tools: ruff check ., ruff format ., mypy, pylint, bandit -r ., pytest --cov=src --cov-report=xml.

---

Phase 3 — Architecture and Style

Refactor only when it reduces warnings or improves testability.

SOLID

• Single Responsibility: split classes/modules that mix persistence, business logic, and presentation.
• Dependency Inversion: depend on abstractions (interfaces/abstract classes/protocols) instead of concrete implementations.

DDD

• Identify Aggregates, Entities, Value Objects, and Repositories.
• Keep domain logic independent of frameworks and UI.

Clean Architecture

• Validate separation between Domain, Application, Infrastructure, and Presentation.
• Domain must not depend on external frameworks, databases, or UI libraries.

---

Phase 4 — Tests and Coverage

For framework-specific commands (xUnit/NUnit/MSTest, Maven/Gradle, pytest/unittest), thresholds, and HTML reports, see the references/ files:

• references/coverage-dotnet.md
• references/coverage-java.md
• references/coverage-python.md

Use the auxiliary dispatcher to auto-detect the stack and run coverage:

bash references/run-coverage.sh

.NET

dotnet test --collect:"XPlat Code Coverage" --results-directory ./TestResults

Java

mvn test
# or
./gradlew test jacocoTestReport

Python

pytest --cov=src --cov-report=term-missing --cov-report=xml

Stabilization Rules

• Fix existing failures before creating new tests.
• Remove or skip problematic infrastructure tests (e.g. JWT, external APIs) only when they require deep refactoring, and document the reason.
• New tests follow BDD style: Given / When / Then (or Dado / Quando / Então for pt-BR projects).

Coverage Goals

Language	Minimum target
.NET	90% line and branch
Java	85% line and branch
Python	90% line and branch

Generate reports with reportgenerator (.NET), JaCoCo (Java), or pytest-coverage (Python).

---

Phase 5 — Documentation and Delivery

README.md

Update with:

• Repository structure (hierarchical tree with descriptions).
• Test coverage table: Total Tests, % Lines, % Branches.
• Technical stack list.
• Business Vision and Technical Vision sections.

CHANGELOG.md

• Follow Keep a Changelog
• Use Semantic Versioning
• Link the changelog in the README.

Finalization

Use Conventional Commits:

• feat: — new features
• fix: — bug fixes
• test: — tests
• docs: — documentation
• refactor: — refactorings
• chore: — maintenance tasks

Restriction: Do not open the Pull Request automatically. Prepare the commit, update the README/CHANGELOG, and generate a Detailed Technical Summary containing all changes so the user can open the PR manually.

---

Quality Checklist

• No high/critical security vulnerabilities remain.
• Static-analysis warnings reduced to acceptable baseline.
• All existing tests pass.
• Coverage report generated and meets the language target.
• README updated with coverage and architecture sections.
• CHANGELOG updated with Unreleased changes.
• Commit message follows Conventional Commits.

Common Mistakes

Mistake	Consequence	How to avoid
throw ex; instead of raise/throw	Stack trace lost, root cause hidden	Re-raise with original trace; add context, do not reset
String concatenation in logs	Allocation/SQLi-style risk, no structured params	Use parameterized logging placeholders
Auto-opening the PR	User loses control of merge timing	Generate the summary; let the user open the PR
New tests before fixing red suite	Unstable baseline, false confidence	Stabilize existing failures first
Skip coverage report	No evidence target was met	Always emit cobertura/jacoco/xml coverage

References

• references/coverage-dotnet.md — .NET coverage (xUnit/NUnit/MSTest, Coverlet, reportgenerator, thresholds).
• references/coverage-java.md — Java coverage (Maven JaCoCo, Gradle JaCoCo, thresholds).
• references/coverage-python.md — Python coverage (pytest-cov, unittest + coverage.py, mypy, thresholds).
• references/run-coverage.sh — Stack-detecting dispatcher that runs the right coverage command.

See Also

• For reviewing a single change before merge, see code-review-and-quality.
• For automated SonarQube issue remediation across stacks, see sonarqube-autofix.

Origin

Adapted from the devin/playbooks/multi-language-quality/PLAYBOOK.md playbook into an agentskills.io-format skill, following the catalog standards (license: MIT, metadata.version, tripartite description with explicit Do NOT use for clause).