@langchain/core/dist/utils/testing/stream.d.cts

Core LangChain.js abstractions and schemas

//#region src/utils/testing/stream.d.ts
/**
 * The `this` context that Vitest provides to custom matchers via `expect.extend`.
 * @see https://vitest.dev/guide/extending-matchers.html
 */
interface ExpectExtendThis {
  isNot?: boolean;
  equals(a: unknown, b: unknown): boolean;
  utils: {
    matcherHint(name: string, received?: string, expected?: string, options?: {
      isNot?: boolean;
    }): string;
    printReceived(value: unknown): string;
    printExpected(value: unknown): string;
  };
}
interface ExpectationResult {
  pass: boolean;
  message: () => string;
  actual?: unknown;
  expected?: unknown;
}
declare function toHaveStreamText(this: ExpectExtendThis, received: unknown, expected: string): Promise<ExpectationResult>;
declare function toHaveStreamReasoning(this: ExpectExtendThis, received: unknown, expected: string): Promise<ExpectationResult>;
type StreamToolCallExpectation = {
  name: string;
  args: Record<string, unknown>;
};
type StreamUsageExpectation = {
  input_tokens?: number;
  output_tokens?: number;
  total_tokens?: number;
  input_token_details?: Record<string, unknown>;
  output_token_details?: Record<string, unknown>;
};
type StreamOutputExpectation = {
  id?: string;
  text?: string;
  toolCalls?: StreamToolCallExpectation[];
  usage?: StreamUsageExpectation;
  responseMetadata?: Record<string, unknown>;
};
declare function toHaveStreamToolCalls(this: ExpectExtendThis, received: unknown, expected: StreamToolCallExpectation[]): Promise<ExpectationResult>;
declare function toHaveStreamUsage(this: ExpectExtendThis, received: unknown, expected: StreamUsageExpectation): Promise<ExpectationResult>;
declare function toHaveStreamOutput(this: ExpectExtendThis, received: unknown, expected: StreamOutputExpectation): Promise<ExpectationResult>;
/** Stream matchers for `expect.extend()`. */
declare const streamMatchers: {
  toHaveStreamText: typeof toHaveStreamText;
  toHaveStreamReasoning: typeof toHaveStreamReasoning;
  toHaveStreamToolCalls: typeof toHaveStreamToolCalls;
  toHaveStreamUsage: typeof toHaveStreamUsage;
  toHaveStreamOutput: typeof toHaveStreamOutput;
};
/**
 * Custom assertion helpers for values returned by `BaseChatModel.streamEvents()`.
 *
 * These matchers consume the stream lazily through the corresponding
 * `ChatModelStream` promise-backed properties.
 *
 * @typeParam R - The assertion return type provided by the test framework.
 */
interface StreamMatchers<R = unknown> {
  /**
   * Asserts that the stream resolves to the expected concatenated text.
   *
   * @param expected - The exact text expected from `ChatModelStream.text`.
   */
  toHaveStreamText(expected: string): R;
  /**
   * Asserts that the stream resolves to the expected concatenated reasoning text.
   *
   * @param expected - The exact reasoning text expected from `ChatModelStream.reasoning`.
   */
  toHaveStreamReasoning(expected: string): R;
  /**
   * Asserts that the stream resolves to the expected ordered tool calls.
   *
   * @param expected - Tool call names and arguments expected from `ChatModelStream.toolCalls`.
   */
  toHaveStreamToolCalls(expected: StreamToolCallExpectation[]): R;
  /**
   * Asserts that the stream resolves to usage metadata matching the expected fields.
   *
   * @param expected - A partial usage metadata object expected from `ChatModelStream.usage`.
   */
  toHaveStreamUsage(expected: StreamUsageExpectation): R;
  /**
   * Asserts that the final streamed output message matches the expected fields.
   *
   * @param expected - A partial output expectation checked against `ChatModelStream.output`.
   */
  toHaveStreamOutput(expected: StreamOutputExpectation): R;
}
//#endregion
export { StreamMatchers, StreamOutputExpectation, StreamToolCallExpectation, StreamUsageExpectation, streamMatchers, toHaveStreamOutput, toHaveStreamReasoning, toHaveStreamText, toHaveStreamToolCalls, toHaveStreamUsage };
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