Test Plan - Gravity Toy

Version: 0.1.0
Date: 2026-04-13
Status: Active visual

1. Purpose

Define the initial verification approach for the Gravity Toy visual.

2. Test Focus

• gravity interaction stability
• absorption and momentum behavior
• preset integrity
• drag-to-launch interaction
• pause/resume correctness
• reduced-motion behavior
• bilingual UI correctness
• desktop and mobile usability

3. Test Levels

3.1 Logic Checks

• mass-to-radius mapping remains stable for small, medium, and heavy bodies
• gravitational pair update uses mutual force accumulation
• merge survivor mass equals combined mass
• merge survivor velocity follows momentum conservation
• fixed Solar star does not drift during updates
• escape-margin removal culls far-off bodies correctly

3.2 Manual Interaction Tests

• load page and confirm the Solar System preset starts automatically
• switch presets and confirm Solar System, Chaos, Binary, and Sandbox each reset cleanly
• drag on desktop and confirm a new orb launches in the drag direction
• hold before release and confirm the ghost circle grows and the spawned orb is visibly heavier
• repeat the drag-to-launch flow on touch/mobile input
• pause the simulation during an active merge/launch effect and confirm visuals freeze in place
• resume and confirm the simulation continues cleanly
• reset the active preset and confirm the current preset state is restored
• toggle language and confirm controls, hint text, and descriptive copy update in NL/EN
• open with ?lang=en and confirm English is used on first load

3.3 Visual Smoke Tests

• canvas renders without console errors
• glow hierarchy is visible on large and small bodies
• motion trails appear on moving orbs
• force lines appear between close orb pairs
• barycenter markers appear on close-pair lines, including pairs with a heavy central body
• launch burst ring appears on spawn
• merge pulse and survivor flash appear on absorption
• hint text appears on load and fades away

3.4 Accessibility and Preference Tests

• all control buttons remain keyboard focusable
• language toggle remains labeled
• prefers-reduced-motion suppresses trails, pulses, launch bursts, and hint animation
• reduced-motion state starts paused as designed

3.5 Docs and Routing Checks

• site/visuals.html links to site/visuals-gravity.html
• site/docs/index.html lists Gravity Toy Docs
• site/visuals-gravity/docs/index.html links to URS, FS, DS, and Test Plan
• site/visuals-gravity/docs/test-plan.html renders after npm run docs:render

4. Acceptance Checks

The current release should be considered acceptable when:

• all four presets load and feel distinct
• user-launched orbs reliably affect the simulation
• pause/resume and reset behave predictably
• key visual feedback effects are present
• NL and EN copy remain correct
• the public docs set is reachable and consistent with the source markdown