Editor diagnostics

A rule that fires in CI arrives an hour late. The shapes this library warns about — a spy declared as the class, an expect() inside subscribe(), a done callback Vitest never calls — are all cheap to fix while the cursor is still on the line and expensive to find afterwards, because every one of them passes.

There is one channel, and it is already in the package: vitest-auto-spy/eslint-plugin. Twelve rules over a real syntax tree, with a fix or a suggestion where the rewrite is decidable — the same rules in the editor and in CI, so nothing passes locally and fails on the build. No editor needs a plugin of this package's own; it needs its ESLint integration switched on, which every IDE below has.

WebStorm and the other JetBrains IDEs

WebStorm, IntelliJ IDEA Ultimate, PhpStorm, PyCharm Professional and RubyMine all run ESLint natively, so the rules light up inline, with no plugin to install — the same twelve checks, in the editor, in the Problems tool window, and under Code → Inspect Code for the whole project.

Install and configure once:

npm i -D vitest-auto-spy eslint

// eslint.config.js — flat config, at the repository root
import autoSpy from 'vitest-auto-spy/eslint-plugin';

export default [
  {
    files: ['**/*.spec.ts', '**/*.spec.tsx', '**/*.test.ts', '**/*.test.tsx'],
    ...autoSpy.configs.recommended,
  },
];

Then in Settings → Languages & Frameworks → JavaScript → Code Quality Tools → ESLint, pick Automatic ESLint configuration — WebStorm finds eslint.config.js and the local eslint itself. Choose Manual only when the config lives outside the project root; there the fields that matter are ESLint package (node_modules/eslint) and Configuration file.

Three things worth knowing, because each one looks like "the rules do not work":

• Flat config only. The legacy .eslintrc plugins: ['vitest-auto-spy'] form resolves plugin names to eslint-plugin-* packages, which a subpath export of this package can never be. WebStorm supports flat config from 2023.3; on an older build, upgrade the IDE rather than the config.
• Scope the block to spec files yourself. Object.defineProperty and an object of vi.fn()s are perfectly reasonable in application code — every rule here is about test code.
• The quick fixes are ESLint's. ⌥⏎ on a highlighted line offers ESLint: Fix current file and, where a rule ships a suggestion, the individual rewrite. no-mocked-for-spy and prefer-as-spy fix on their own — both touch a type, so the worst a wrong one can do is fail to compile. The rest suggest, because the replacement changes behaviour and should be read before it is accepted.

Prefer to see everything at once during a migration? Code → Inspect Code… with the scope set to the test sources lists every finding grouped by rule, which is the shape a "how much of this suite still hand-rolls its doubles" question actually needs.

A native JetBrains plugin is not planned

A plugin in the JetBrains Marketplace would duplicate an integration the IDE already has, and would then have to keep a second copy of twelve rules — in Kotlin — in step with the TypeScript ones. Where the ESLint route genuinely cannot reach (a repository with no ESLint at all), the honest fix is four lines of eslint.config.js, not a second implementation.

VS Code, Cursor, Windsurf, VSCodium

Install the ESLint extension and the flat config above is enough: the same twelve rules, inline and in the Problems panel.

// .vscode/settings.json
{
  // Applies the two rules that fix on their own — `no-mocked-for-spy` and `prefer-as-spy` — when
  // the file is saved. The rest offer their rewrite as a suggestion on ⌘. instead, because each one
  // changes behaviour and should be read before it is accepted.
  "editor.codeActionsOnSave": { "source.fixAll.eslint": "explicit" },

  // Flat config is the default from ESLint 9; this line only matters on an older ESLint.
  "eslint.useFlatConfig": true
}

Cursor, Windsurf and VSCodium install that ESLint extension from Open VSX and read the same .vscode/settings.json, so nothing about the setup changes there.

What gets underlined

Shape	Why it is wrong	Rule
expect() inside subscribe()	a silent stream never runs the callback — the test passes having asserted nothing	no-expect-in-subscribe
it('x', (done) => …)	Vitest passes a TestContext; the test passes having run almost none of its body	no-done-callback
a .then() chain that asserts and is never awaited	the assertion lands after the test has finished, where nothing fails	no-floating-assertion
{ provide: X, useValue: { m: vi.fn() } }	provideAutoSpy(X) stays in step when the class grows a method	prefer-provide-auto-spy
an object of vi.fn()s standing in for a class	createSpyFromClass(X) reads the prototype instead of a list that goes stale	prefer-create-spy-from-class
TestBed.inject<X>(), or a cast on the way out	injectSpy(X) returns Spy<X> with no generic and no assertion	prefer-inject-spy
vi.mocked() over something that is already a spy	Mocked<T> loses calledWith, resolveWith and nextWith — auto-fixed	no-mocked-for-spy
TestBed.inject(X) as Spy<X>	the cast a jest-auto-spies suite carries everywhere stops compiling here — asSpy(…) makes the same claim without one, and is auto-fixed	prefer-as-spy
Object.defineProperty in a spec	nothing records the undo — mockReadonlyProp / mockValueProp do	no-object-define-property
an exported module-level object of vi.fn()s	under isolate: false every spec file shares one set of spies	no-shared-module-level-mock
the same token provided twice in one array	the second provider silently replaces the first	no-overridden-provider
TestBed.inject() before an override* in the suite	injecting instantiates the module, and every later override throws	no-inject-before-override

Each message ends with a link to the README recipe that shows the replacement, so the rule never only says "don't". The full descriptions, severities and the reasoning behind which rules fix and which only suggest are in ESLint plugin.

The shapes ESLint cannot see are covered where they surface instead: importing the wrong entry point for the runner, or calling nextWith without import 'vitest-auto-spy/rxjs', both throw at run time with a message that names the fix and links the page — see Errors that name their own fix.