Testing & Quality📋

Testing isn't optional — it's how you prove you care.

Quality here isn't a checklist. It's a design force — every layer of the stack has a gate, every gate has teeth, and nothing reaches production without proving it belongs there.

First Principles📋

• A gate is binary — pass or fail, never "mostly acceptable"
• Gates have teeth — a warning is not a gate; exit code 1 is
• Gates belong in the feedback loop — pre-push or CI, not PR review
• Coverage is a floor, not a ceiling — mutation score proves the tests mean something
• Property tests find what unit tests assumed away
• Measure at natural granularity — per-method, per-type, per-namespace; never global averages that mask local debt
• Self-hosted — QualityGate gates itself: 256 tests, 100% line/branch coverage, mutation score 1.0

Test-Driven Design📋

• TDD — tests drive design, not just verify it
• No mocking frameworks — FakeHttpClient, hand-written fakes, deterministic tests
• Mutation testing (Stryker) — test quality score >= 0.95
• 100% code coverage as design pressure, not a vanity metric
• Property-based testing (fast-check) for fuzzy invariants

Professional Testing at Scale📋

• Revived ~800 unit tests at BIM&CO — built a multi-threaded execution framework with async lambda encapsulation, cutting test suite from non-functional to running in ~20 minutes
• Aspire testing layer — mini framework on top of .NET Aspire to reduce test boilerplate (BIM&CO)
• CucumberJS E2E — set up the npm/TypeScript + CucumberJS test stack with Selenium infrastructure (Qwant)
• Selenium — E2E testing coordination across multiple projects (Qwant, AUSY)

Code Quality as Static Analysis📋

Not opinions — metrics. QualityGate runs Roslyn-powered analysis on every build: cyclomatic complexity, cognitive complexity, afferent/efferent coupling (Ca/Ce), cohesion (LCOM4), maintainability index. Thresholds live in quality-gate.yml, enforced in CI with pass/fail exit codes. The build doesn't warn — it fails.

Visual Quality as Baselines📋

Every page is screenshotted across 4 themes (dark, light, dark-hc, light-hc) and multiple viewports. Baselines are checked in. When a pixel changes, the diff is visible and intentional — or the test fails.

New pages get auto-generated baselines on first run. A smoke mode tests a curated set of stable pages on every push, so content additions don't break the suite. Full regression runs on demand.

Accessibility as a Gate, Not an Afterthought📋

axe audits on every page, accent color contrast matrix testing, ARIA role verification, keyboard-first navigation, screen-reader announcements. Accessibility isn't a separate pass — it's woven into the same test pipeline that checks rendering.

Requirements as Compile-Time Proof📋

Features are abstract classes with acceptance criteria as abstract methods. Tests link to features via typed decorators. A compliance scanner verifies 100% AC coverage — if an acceptance criterion has no test, the build knows.

The Gate Before Push📋

Husky pre-push hook: unit tests + smoke Playwright + compliance scan. All three must pass before git push succeeds. No bypassing, no --no-verify. If the gate fails, the code stays local until it's fixed.

C# Quality Gates📋

TypeScript Quality Gates📋