@crbroughton/failsafe-vitest

Custom vitest matchers for @crbroughton/failsafe's Result type.

Install

pnpm add -D @crbroughton/failsafe-vitest

Requires @crbroughton/failsafe and vitest as peer dependencies (bring your own versions — this package doesn't pin them for you).

Usage

Import it once, typically from a vitest setupFiles entry:

// vitest.setup.ts
import "@crbroughton/failsafe-vitest"

// vitest.config.ts
export default defineConfig({
  test: { setupFiles: ["./vitest.setup.ts"] },
})

Then use the matchers directly:

expect(result).toBeOk()
expect(result).toBeOk(42) // also deep-equal checks .value

expect(result).toBeErr()
expect(result).toBeErr("ParseError") // checks .error.tag only, not the full shape

Both compose with .not:

expect(result).not.toBeOk()
expect(result).not.toBeErr()

Why tag-only for toBeErr()?

Tests usually care which error occurred more than its exact payload — checking only .error.tag keeps assertions focused on that, without tests breaking every time an unrelated field is added to an error's shape.

License

MIT