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TypeScript · testing

no-unsafe-mock-casting

eslint:no-unsafe-mock-casting

Disallow casting to mock types like `jest.Mock` or `vi.Mock`. Use `vi.mocked()` or `jest.mocked()` instead.

Default
error
Fix
none
Languages
typescript

Why

A type assertion can claim an unmocked value is a mock and bypass checking between the original callable and the mock API.

Fix

Use the test framework's `mocked` helper to obtain the typed mock reference.

Before / after

Executed by this rule’s unit tests.

Before

Do not assert that a value is a mock

src/client.test.ts · focus
import type * as vi from "vitest"; const m = myFn as vi.Mock;

After

Use the framework helper

src/client.test.ts · focus
const m = vi.mocked(myFn);

Limits

  • Only mock types imported from Vitest or Jest modules are inspected.

Message IDs

unsafeMockCast