chore(lambda-rs): Increase code coverage for rendering

[vmarcella]

Summary

Increase lambda-rs render module test coverage by
adding adapter-backed GPU tests, a feature-gated window/surface smoke runner for
coverage, and a small render refactor to support offscreen-only rendering paths.

Related Issues

Changes

• Add comprehensive tests across crates/lambda-rs/src/render/** to exercise
  pipeline/pass/bind-group/buffer/encoder/targets/texture/validation paths.
• Update GPU-dependent tests to run automatically when an adapter is available:
  attempt primary adapter first, then wgpu fallback/virtual adapter; optionally
  enforce adapter presence via LAMBDA_REQUIRE_GPU_ADAPTER=1.
• Centralize GPU creation logic for tests in a single helper implementation.
• Add rustdoc on all render tests describing what each test validates.
• Update CI workflows to enforce adapter-backed tests on Linux Vulkan jobs (Mesa
  lavapipe) by setting LAMBDA_REQUIRE_GPU_ADAPTER=1.
• Ignore generated coverage artifacts in .gitignore.
• Flatten docs paths for specs/tutorials (remove nested area folders), update
  indices/links, and remove outdated template guidance.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• Feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (updates to docs, specs, tutorials, or comments)
• Refactor (code change that neither fixes a bug nor adds a feature)
• Performance (change that improves performance)
• Test (adding or updating tests)
• Build/CI (changes to build process or CI configuration)

Affected Crates

• lambda-rs
• lambda-rs-platform
• lambda-rs-args
• lambda-rs-logging
• Other:

Checklist

• Code follows the repository style guidelines (cargo +nightly fmt --all)
• Code passes clippy (cargo clippy --workspace --all-targets -- -D warnings)
• Tests pass (cargo test --workspace)
• New code includes appropriate documentation
• Public API changes are documented
• Breaking changes are noted in this PR description

Testing

Commands run:

cargo +nightly fmt
cargo test -p lambda-rs --lib --tests

Coverage workflow used for adapter-backed + window/surface coverage:

cargo llvm-cov clean -p lambda-rs
cargo llvm-cov -p lambda-rs --lib --tests --no-report -- --include-ignored
cargo llvm-cov report -p lambda-rs --json --output-path coverage/lambda_rs_cov.json

Manual verification steps (if applicable):

1. Confirm render folder per-file line coverage is ≥80% in coverage/lambda_rs_cov.json.

Screenshots/Recordings

N/A (no UI changes).

Platform Testing

• macOS
• Windows
• Linux

Additional Notes

• Linux CI is configured to prefer Mesa's Vulkan software implementation
  (lavapipe) and now enforces adapter-backed render tests via
  LAMBDA_REQUIRE_GPU_ADAPTER=1.

[Copilot]

Pull request overview

This PR increases lambda-rs render-module coverage by adding many targeted unit/integration tests (including adapter-backed GPU tests), centralizing GPU test setup, and refactoring RenderContext to support offscreen-only rendering paths. It also updates CI/workflows to enforce adapter availability for coverage runs and ignores generated coverage artifacts.

Changes:

• Add extensive render tests across builders, enum/platform mappings, validation paths, and GPU-backed encode/submit flows.
• Introduce centralized GPU test helpers with primary + fallback adapter selection and optional enforcement via LAMBDA_REQUIRE_GPU_ADAPTER.
• Refactor RenderContext to allow surface: Option<WindowSurface> and support headless/offscreen rendering flows; update CI env accordingly.

Reviewed changes

Copilot reviewed 23 out of 24 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
crates/lambda-rs/src/render/window.rs	Adds WindowBuilder default/override tests and a best-effort window creation smoke test (non-macOS).
crates/lambda-rs/src/render/viewport.rs	Adds tests for coordinate clamping and helper tuple conversions.
crates/lambda-rs/src/render/vertex.rs	Adds rustdoc to an existing vertex builder test.
crates/lambda-rs/src/render/validation.rs	Adds tests for alignment and render validation helpers (dynamic offsets, instance ranges/bindings).
crates/lambda-rs/src/render/texture.rs	Adds mapping/flag tests plus GPU-backed texture build validation and 3D path coverage.
crates/lambda-rs/src/render/targets/surface.rs	Adds tests for present mode conversions, surface error mapping, and display formatting.
crates/lambda-rs/src/render/targets/offscreen.rs	Switches tests to centralized GPU helper and adds additional offscreen target behavior tests.
crates/lambda-rs/src/render/surface.rs	Adds tests for present mode conversions, error mappings, and SurfaceConfig field mapping.
crates/lambda-rs/src/render/shader.rs	Adds tests for inline and file-based shader compilation paths.
crates/lambda-rs/src/render/render_pass.rs	Adds tests for depth clear clamping, MSAA sanitization, and builder toggles.
crates/lambda-rs/src/render/pipeline.rs	Adds enum mapping tests and GPU-backed pipeline construction/alignment tests.
crates/lambda-rs/src/render/mod.rs	Refactors RenderContext to make surface optional and adds substantial GPU-backed encode/render tests.
crates/lambda-rs/src/render/mesh.rs	Adds additional MeshBuilder tests including OBJ loader parsing.
crates/lambda-rs/src/render/instance.rs	Adds tests for builder options and platform mapping of instance flags/backends.
crates/lambda-rs/src/render/gpu.rs	Adds force_fallback, adapter-required env gating, centralized test GPU creation helpers, and mapping/display tests.
crates/lambda-rs/src/render/encoder.rs	Adds test-only render pass encoder helper and GPU-backed encoder/validation tests.
crates/lambda-rs/src/render/command.rs	Adds/updates test doc for index format mapping.
crates/lambda-rs/src/render/color_attachments.rs	Adds tests for attachment builder behavior incl. MSAA missing-view panic path.
crates/lambda-rs/src/render/buffer.rs	Adds multiple unit tests plus GPU-backed buffer write/wrapper tests.
crates/lambda-rs/src/render/bind.rs	Adds comprehensive bind layout/group tests and updates texture binding docstring.
.gitignore	Ignores generated coverage/ artifacts.
.github/workflows/release.yml	Enforces adapter-backed tests via LAMBDA_REQUIRE_GPU_ADAPTER=1 in Vulkan CI.
.github/workflows/coverage.yml	Enforces adapter-backed tests via LAMBDA_REQUIRE_GPU_ADAPTER=1 for coverage job.
.github/workflows/compile_lambda_rs.yml	Enforces adapter-backed tests via LAMBDA_REQUIRE_GPU_ADAPTER=1 in Vulkan CI matrix.

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✅ Coverage Report

📊 View Full HTML Report (download artifact)

Overall Coverage

Metric	Value
Total Line Coverage	78.02%
Lines Covered	10049 / 12880

Changed Files in This PR

File	Coverage	Lines
crates/lambda-rs/src/render/bind.rs	95.25%	281/295
crates/lambda-rs/src/render/buffer.rs	92.56%	224/242
crates/lambda-rs/src/render/color_attachments.rs	96.03%	121/126
crates/lambda-rs/src/render/command.rs	100.00%	13/13
crates/lambda-rs/src/render/encoder.rs	84.09%	502/597
crates/lambda-rs/src/render/gpu.rs	76.88%	133/173
crates/lambda-rs/src/render/instance.rs	93.23%	124/133
crates/lambda-rs/src/render/mesh.rs	91.80%	112/122
crates/lambda-rs/src/render/mod.rs	78.79%	1137/1443
crates/lambda-rs/src/render/pipeline.rs	91.19%	476/522
crates/lambda-rs/src/render/render_pass.rs	80.61%	266/330
crates/lambda-rs/src/render/shader.rs	94.64%	53/56
crates/lambda-rs/src/render/surface.rs	N/A	(no coverage data)
crates/lambda-rs/src/render/targets/offscreen.rs	83.04%	235/283
crates/lambda-rs/src/render/targets/surface.rs	40.56%	73/180
crates/lambda-rs/src/render/texture.rs	84.28%	327/388
crates/lambda-rs/src/render/validation.rs	100.00%	121/121
crates/lambda-rs/src/render/vertex.rs	92.00%	46/50
crates/lambda-rs/src/render/viewport.rs	95.00%	57/60
crates/lambda-rs/src/render/window.rs	50.53%	48/95

PR Files Coverage: 83.17% (4349/5229 lines)

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_{Last updated: 2026-02-09 06:54:58 UTC · Commit: e62b5c3}