Two lanes:

Plain-Node Jest (jest.unit.config.mjs), no build, no Blockbench. Covers pure-logic modules that don't touch host globals.

• unit/easing.test.ts — easing curve endpoints, step, arg parsing, EASING_OPTIONS
• unit/misc.test.ts — roundTo, roundToNth, scrubUndefined, detectCircularReferences, mapObjEntries
• unit/stopwatch.test.ts — start/stop contract, Stopwatch.function
• unit/minecraftUtil.test.ts — resource-location / data-pack / resource-pack path parsing, toSmallCaps, sanitizeStorageKey, resolveBlockstateValueType
• unit/fileUtil.test.ts — path normalisation, env-var expansion, swapPathRoot, tag-path detection
• unit/collectionFile.test.ts — .bpcollection parsing/validation, member and pack path resolution relative to the collection
• unit/trueTypeFont.test.ts — TrueType/OpenType parsing for the ttf font provider: cmap formats 4 and 12, outline format (glyf vs CFF), metrics, malformed-file errors

unit/setup.ts binds the PathModule global to node:path; unit/__stubs__/ replaces host-dependent sibling imports (fs accessor, block/registry lookups) with no-ops so the pure functions can be imported.

jestbench: loads the built plugin into a real headless Blockbench (jest.config.mjs + blockbench.config.mjs). Needs a production build first and xvfb-run on Linux. First run downloads Blockbench + Minecraft assets to ~/.envbench.

Some internals are exposed on the AnimatedJava global purely so these tests can reach them: renderRig, renderProjectAnimations, hashRig, hashAnimations, and the Interaction outliner element class.

Outliner elements, variants & keyframes

• outliner-elements.test.ts — the four types AJ registers (text_display, vanilla_item_display, vanilla_block_display, interaction): type registration, constructor defaults, property accessors, renderRig node mapping, codec round-trip
• variants.test.ts — Variant name uniqueness / single-default rule, toJSON/fromJSON, TextureMap (map / remap / prune), codec round-trip, renderRig variant output
• custom-keyframes.test.ts — the reshaped EffectAnimator channels, the variant / function / execute_condition / repeat keyframe accessors, animation-renderer frame output, codec round-trip

Format & migration

• blueprint-codec-roundtrip.test.ts — bones / cubes / locator / text display / variants / animations / settings survive a compile → parse
• blueprint-fixtures-load.test.ts — every committed sample project (test_blueprints/, test_ajmodels/, incl. a 1.4 .ajmodel) migrates through the DFU chain and loads
• blueprint-texture-groups.test.ts — regression for #407 (texture groups)
• texture-name-sanitizer.test.ts — regression for #337 (texture name rules)

Export pipeline

• rig-renderer.test.ts — outliner → IRenderedRig: node-type mapping, includes_custom_models, texture collection, hashRig change detection
• animation-renderer.test.ts — keyframe baking to IRenderedAnimation: per-tick frame count, per-node transforms, animated-channel change, hashAnimations
• molang-baking.test.ts — a Molang expression keyframe bakes identically to its literal; animation_variable_placeholders round-trip
• export-pipeline.test.ts — exportProject writes a real data pack + resource pack; runs across five target versions (1.20.4 / 1.21.2 / 1.21.5 / 26.2 / 26.3, one per getMCBFilesByVersion branch)
• export-contents.test.ts — inspects a real player export: pack.mcmeta pack_format, summon function body, a function per animation, scoreboard setup, block atlas, bone model JSON (geometry + textures), item model definitions, texture PNGs
• ajmeta-incremental.test.ts — delete a bone from an exported project, re-export, assert the stale model file + ajmeta entry are removed
• plugin-mode-export.test.ts — plugin-mode single-JSON export (pluginCompiler) shape
• blueprint-collection.test.ts — Blueprint Collections: the .bpcollection tab (format, mode, page cards, drag-reorder and remove), saving links/unlinks members and relinks on Save As, folder and zip collection exports, saving unsaved tab edits before exporting, members exporting with the open tab's settings, removing rigs of members that left (but not rigs exported outside the collection), duplicate-ID and plugin-mode refusals

Minecraft asset systems

• minecraft-assets.test.ts — assetManager JSON/PNG lookups, blockModelManager / itemModelManager vanilla mesh builds, getBlockState
• vanilla-display-rendering.test.ts — bmrModelRenderer blockstate variant selection (stairs facing, slab type) and item-model predicate + display-mode resolution
• preview-resource-pack-font.test.ts — regression for a stale font-layout cache
• ttf-font-provider.test.ts — ttf font providers (test-packs/ttf-font-pack/): FreeType (1.20.5+) vs stb_truetype (1.20.4) metrics, size / oversample / shift / skip, fallthrough to the next provider, CFF refusal on 1.20.5+, font reload on a target-version change, text-display mesh batches

UI & mods

• ui-registration.test.ts — the Blueprint format, bar actions, panels and menu bar all register; the src/mods/ class-property patches (Group, Keyframe, Locator) apply; the public AnimatedJava API surface
• ui-behaviour.test.ts — firing actions does what clicking would: create-element actions add + select a node (and stay disabled off a Blueprint), the variant-panel actions create / duplicate / delete (never the default), and the About / Blueprint Settings / variant config / export-progress dialogs open and close

• deeper datapackCompiler output semantics (NBT of summoned entities, macro/storage animation modes, interaction/locator command wiring) — only structural checks today
• the resource-pack font generation path (custom fonts, glyph atlas) beyond the stale-cache regression
• multi-variant item model definitions and per-variant model overrides
• dialog form round-trips (reading / writing settings through the Blueprint Settings sidebar UI) and Svelte component rendering — only open/close is checked
• animationController support and src/mods/ behavioural patches (camera plugin bridge, painter, show-default-pose)