Function assertLeft

packages/vitest/src/utils.ts:214–220

(
  either: Either.Either<R, L>,
  expected: L,
  ..._: Array<never>
)

 * @since 0.21.0
 */
export function assertLeft<R, L>(
  either: Either.Either<R, L>,
  expected: L,
  ..._: Array<never>
): asserts either is Either.Left<L, never> {
  deepStrictEqual(either, Either.left(expected))
}

/**
 * Asserts that `either` is `Right`.