/**
 * Test doubles for the shim's stdio streams, so dispatch can be exercised without
 * forking a child process. Kept beside the shim rather than under `test/` because
 * what these implement is the shim's own stream contract.
 */
import type { CanvasShimStreams } from "./index.js";
/** A readable side whose chunks are pushed by the test. */
export declare class FakeCanvasInput {
    private listener;
    setEncoding(_encoding: "utf8"): this;
    on(_event: "data", listener: (chunk: string) => void): this;
    /** Deliver a chunk as if the host had written it. */
    feed(chunk: string): void;
}
/** Streams plus the lines the shim wrote, for assertions. */
export interface FakeCanvasStreams extends CanvasShimStreams {
    input: FakeCanvasInput;
    /** Every line written by the shim, parsed. */
    written: unknown[];
}
/** Build injectable streams whose writes are collected instead of sent to stdout. */
export declare function fakeCanvasStreams(extensionId?: string): FakeCanvasStreams;
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