Testing

CI runs the parity, behavior, and contract checks on every push (.github/workflows/ci.yml).

Naming note: the editor UI is built on Dear PyGui, which wraps Dear ImGui — that is why the UI test files are prefixed test_imgui_.

Headline numbers

99/99 parity

Python vs C++ simulation output — every case matches

27 templates

Trails load/search/apply + thumbnails and user-preset round-trip

Perf gate

C++ throughput floor enforced (tools/check_perf.py)

Full test matrix

Test	Covers
`core/test_parity.py`	Python vs C++ simulation output — 99/99 passing
`core/test_behavior.py`	Simulation behavior, morph-window keys, performance (~2–3 ms @ 2,000 particles)
`tests/test_imgui_build.py`	UI builds without errors (blend dropdown, seed box, force-field widgets)
`tests/test_imgui_logic.py`	Headless simulation logic (C++ path)
`tests/test_imgui_nav.py`	Viewport navigation (WASD/arrows, Q/E, F, Shift×3) + sidebar splitter hover/drag
`tests/test_imgui_color.py`	Per-state color persistence across birth/death switches
`tests/test_imgui_mesh.py`	Uploaded models render as meshes, tint, culling, LOD
`tests/test_imgui_morph.py`	Shape cross-fade window (edges, split alpha, legacy fallback)
`tests/test_imgui_upload.py`	Upload chain, OBJ parsing, big-JSON node names, bone-node fallback
`tests/test_imgui_raster.py`	Raster path: PPM conversion, GL orientation, auto-switch, no-GL fallback
`tests/test_preview_blobs.py`	Model-blob embedding for the browser preview
`tests/test_contracts.py`	Generated bindings = source, C++ order, schema accept/reject, migration
`tests/test_gl_blend.py`	Pixel-level GL formulas per blend mode + fallbacks
`tests/test_blend_modes.py`	Blend round-trip, sanitize, sample layers
`tests/test_seed.py`	Seed replay identical (Python + C++), divergence, seed-0 legacy
`tests/test_fields.py`	Field formulas, off-identical, perturb/replay, collision, attractor (Py + C++)
`preview/test_blend.mjs`	Extension blend mappings + resolution (stubbed runtimes)
`preview/test_seed.mjs`	Preview seeded replay and extension RNG helper behavior (not cross-runtime particle-record parity)
`preview/test_fields.mjs`	Extension helpers == Python + preview field behavior
`preview/test_trails.mjs`	Preview trails: bake parity vs Python (exact), store semantics, engine wiring 2D/3D, style helpers
`preview/test_ext_trails.mjs`	Extension trails: shipped-helper parity, 3D ribbons/hide (real three.js), 2D ribbons/hide (stub PIXI), hybrid + legacy
`preview/test_ext_runtime.mjs`	Shipped 3D runtime headless (stub gdjs + real three.js)
`preview/test_engine.mjs`, `test_engine3d.mjs`, `test_guides.mjs`, `test_server.py`	Browser preview engine, 2D/3D scene layers, guides
`preview/test_frame_buffers.mjs`	Typed-array frame contents and stable buffer reuse
`preview/test_engine_parity.mjs` + `engine_parity_baseline.json`	Seeded 120-frame 2D/3D snapshots against the pre-refactor browser simulation; this does not assert parity with GDevelop
`preview/test_models.mjs`	Model-blob caching and live-push behavior
`preview/test_morph.mjs`	Preview-side `morphAt()` cross-fade sampling
`preview/test_bake.mjs` / `test_ext_bake.mjs`	Skinned-mesh rest-pose baking (preview + shipped extension)
`tests/test_trails_schema.py`	`TRAIL_SCHEMA` ↔ defaults sync, clamps, LUT sizes
`tests/test_trails_roundtrip.py`	Trail files byte-stable round-trip + old-file heal
`tests/test_trails_parity.py`	Python ↔ C++ trail width/gradient/scalars
`tests/test_trails_perf.py`	Trail update/bake perf budgets
`tests/test_trails_flow.py`	Time/distance emission, exact spacing, tick FIFO, trail death
`tests/test_trails_render.py`	Ribbon-strip math + viewport smoke
`tests/test_trails_templates.py`	27 templates load/search/apply, thumbnails, user-preset round-trip
`tests/test_view2d_zoom.py`	World-space 2D zoom math, anchors, raster agreement
`tools/check_perf.py`	CI perf gate: C++ throughput floor
`render/test_gl.py`, `test_clip.py`, `test_cost.py`	GL context init, projection parity, render-cost profiling

Running locally

python tools/generate_contracts.py --check   # contract drift gate
python core/test_parity.py                   # Python vs C++
python -m pytest tests/ -q                   # editor + schema suite
node preview/test_ext_trails.mjs             # extension trails headless
python tools/check_perf.py                   # throughput floor

The packaged app has its own smoke path: python editor/studio_imgui.py --smoke 120 boots the UI for 120 frames and reports particle count + FPS.