/**
 * Shared test assertions for the `@fuzdev` ecosystem.
 *
 * Extends the fuz-stack testing conventions (`assert` from vitest, tests in `src/test/`,
 * plain object mocks) with reusable helpers for patterns that appear across multiple repos.
 * Only depends on vitest — safe for fuz_util's zero-runtime-deps constraint.
 *
 * @module
 */
import type { Logger } from './log.js';
/**
 * Narrows a discriminated union by a literal property value, failing the test
 * if the value doesn't match. The assertion signature propagates the narrowed
 * type so callers can access variant-specific fields directly.
 *
 * Works with any discriminator key (`kind`, `ok`, `type`, `_tag`, etc.).
 *
 * @example
 * ```ts
 * type Shape =
 *   | {kind: 'circle'; radius: number}
 *   | {kind: 'square'; side: number};
 * const shape: Shape = get_shape();
 * assert_property(shape, 'kind', 'circle');
 * assert.strictEqual(shape.radius, 5); // `radius` now typed as `number`
 * ```
 */
export declare function assert_property<R extends object, P extends keyof R, const V extends R[P]>(obj: R, property: P, value: V): asserts obj is Extract<R, Record<P, V>>;
/**
 * Asserts that `fn` rejects with an `Error`.
 * Optionally matches the error message against `pattern`.
 * Returns the caught `Error` for further assertions by the caller.
 *
 * `assert.fail` is placed after the catch block so that assertion failures
 * from the test itself are not swallowed by the catch.
 *
 * @param fn - async function expected to reject
 * @param pattern - optional regex to match against the error message
 * @returns the caught `Error`
 */
export declare const assert_rejects: (fn: () => Promise<unknown>, pattern?: RegExp) => Promise<Error>;
/**
 * A mock `Logger` with `vi.fn()` methods and call tracking arrays.
 * Assignable to `Logger` for use in code under test.
 * Each tracking array captures the first argument of each call.
 * For full call details, use `vi.fn()` introspection on the methods directly.
 */
export type MockLogger = Logger & {
    error_calls: Array<unknown>;
    warn_calls: Array<unknown>;
    info_calls: Array<unknown>;
    debug_calls: Array<unknown>;
};
/**
 * Creates a mock `Logger` with `vi.fn()` on each logging method
 * and tracking arrays for inspecting logged messages.
 * Follows the fuz-stack convention of plain object mocks over mocking libraries.
 */
export declare const create_mock_logger: () => MockLogger;
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