Comparison

How vitest-auto-spy compares to other mocking / auto-spy libraries. The niche: the only auto-spy library that reads a class and gives a fully-typed spy of every method with return-type-aware control helpers — across any Vitest-compatible runtime and framework.

Library	Reads a class?	Return-type-aware helpers?	Runtime	We win on
jest-auto-spies	✅	✅	Jest only	Vitest/Bun/node:test successor, same API — direct migration path.
@bugsplat/vitest-auto-spies	✅	✅	Vitest only	Same class-based API plus Bun & node:test, type-only createAutoMock, framework recipes, console spies, and zero runtime deps (it depends on @hirez_io/auto-spies-core; rxjs < 8 cap — we support rxjs 8).
vitest-mock-extended	❌ (Proxy)	❌	Vitest	Return-type ergonomics and reading a real class. Its type-only mode is matched by createAutoMock / mockDeep, with the helpers kept.
@golevelup/ts-vitest	partial	❌	Vitest	Typed Promise/Observable helpers + explicit class→spy + mustBeCalledWith.
ts-auto-mock	❌ (transform)	❌	Jest/ts	No compiler transformer to install — runtime-only, no toolchain coupling.
sinon	❌ (manual)	❌	Any	Auto-generated + fully typed vs manual + loosely typed.
testdouble.js	partial	❌	Any	Stronger typing, return-type-aware helpers, framework recipes.

Pitch: the only auto-spy library that reads a class and gives a fully-typed spy of every method with return-type-aware control helpers (resolveWith / nextWith / calledWith) — across any Vitest-compatible runtime and framework.

Feature by feature

	vitest-auto-spy	jest-auto-spies	vitest-mock-extended	@golevelup/ts-vitest	sinon
Spy every method of a class in one call	✅	✅	❌	partial	❌
Mock from a type/interface	✅	❌	✅	✅	❌
Recursive deep mock	✅	❌	✅	❌	❌
Spy-free data double (createMock)	✅	❌	❌	❌	❌
resolveWith / rejectWith	✅	✅	❌	❌	❌
nextWith / nextWithValues (RxJS)	✅	✅	❌	❌	❌
calledWith / mustBeCalledWith	✅	✅	calledWith	❌	❌
Getter / setter spies	✅	✅	❌	❌	✅
Vitest	✅	❌	✅	✅	✅
Bun (bun:test)	✅	❌	❌	❌	partial
node:test	✅	❌	❌	❌	partial
Angular TestBed under bun test	✅	❌	❌	❌	❌
Runtime dependencies	0	1	1	0	4

Dependency counts are each package's own dependencies on npm, checked 2026-08-26 — @hirez_io/auto-spies-core for jest-auto-spies, ts-essentials for vitest-mock-extended, and four @sinonjs/* + diff packages for sinon.

Beyond the class spy

The tables above compare the part every one of these libraries does. What none of the others ship alongside it:

• Angular's TestBed under bun test — Bun ships no DOM and cannot resolve templateUrl, so Angular specs do not run there at all. One preload closes both gaps.
• renderShallow and createWithAutoSpies — the shallow-TestBed copy-paste and DI-driven instantiation as one call each.
• stable / flushEffects and toHaveSignalValue — zoneless waiting and a signal matcher, for a codebase where detectChanges() is no longer enough.
• Observable assertions that fail when the stream stays silent, duck-typed so they pull in no rxjs.
• setupFakeTimers() / advanceTimers() — an advance that also drains the microtasks a bare advanceTimersByTime() leaves pending, and flushEventLoop / settleDynamicImport for the queue the clock does not reach at all.
• mockConstructor / stubConstructor — a double the code under test can call with new, which a runner's own vi.fn(() => instance) is not.
• fakeAsync and waitForAsync on Vitest — zone.js/testing installs its ProxyZone through Jasmine and Jest hooks only, so both throw until this patch is imported.
• assertMocked / moduleNamespace — proof that a vi.mock() actually applied under a bundler, instead of a spec quietly asserting on the real module.
• setupAutoSpy({ strayRejections: true }) — the promise rejections zone.js drains into console.error and no further, turned into failed tests. Nothing else on this list looks there: a swallowed rejection never reaches the channel Vitest watches, so a spec that asserts inside a .then() nobody awaits stays green and exits 0.
• setupAutoSpy({ pruneMockRegistry: true }) — the Set inside @vitest/spy that every vi.fn() joins and that nothing ever takes anything out of, kept to the mocks that outlive a file. On isolate: false it is what makes clearMocks cost more with every test already run, and what keeps a whole run's recorded arguments — and the component trees behind them — alive in one worker.
• Twelve ESLint rules versioned together with the API they recommend, and setupAutoSpy() for the test-run hygiene a shared environment needs.
• Per-file TestBed diagnostics — which specs actually pay for TestBed, and by how much.
• compareTestRuns — whether the migration that brought you here lost a test, from the two sets of names rather than from two totals that happen to match.

Where another library is the better answer

• You are on Jest and staying there. jest-auto-spies is the same API; there is nothing to gain from switching runner just for this.
• You only ever mock interfaces, never classes, and want nothing else.vitest-mock-extended is smaller and does exactly that. createAutoMock / mockDeep cover the same ground here if you want the helpers too — the two are complementary, not exclusive.
• You need sandboxes, fake servers, or a full test-double toolkit. sinon is a wider tool; this package is deliberately only about turning a type or a class into a typed spy.