src/test-utils/send-payload-contract.ts

import { expect, it, type Mock } from "vitest";

type PayloadLike = {
  mediaUrl?: string;
  mediaUrls?: string[];
  text?: string;
};

type SendResultLike = {
  messageId: string;
  [key: string]: unknown;
};

type ChunkingMode =
  | {
      longTextLength: number;
      maxChunkLength: number;
      mode: "split";
    }
  | {
      longTextLength: number;
      mode: "passthrough";
    };

export function installSendPayloadContractSuite(params: {
  channel: string;
  chunking: ChunkingMode;
  createHarness: (params: { payload: PayloadLike; sendResults?: SendResultLike[] }) => {
    run: () => Promise<Record<string, unknown>>;
    sendMock: Mock;
    to: string;
  };
}) {
  it("text-only delegates to sendText", async () => {
    const { run, sendMock, to } = params.createHarness({
      payload: { text: "hello" },
    });
    const result = await run();

    expect(sendMock).toHaveBeenCalledTimes(1);
    expect(sendMock).toHaveBeenCalledWith(to, "hello", expect.any(Object));
    expect(result).toMatchObject({ channel: params.channel });
  });

  it("single media delegates to sendMedia", async () => {
    const { run, sendMock, to } = params.createHarness({
      payload: { text: "cap", mediaUrl: "https://example.com/a.jpg" },
    });
    const result = await run();

    expect(sendMock).toHaveBeenCalledTimes(1);
    expect(sendMock).toHaveBeenCalledWith(
      to,
      "cap",
      expect.objectContaining({ mediaUrl: "https://example.com/a.jpg" }),
    );
    expect(result).toMatchObject({ channel: params.channel });
  });

  it("multi-media iterates URLs with caption on first", async () => {
    const { run, sendMock, to } = params.createHarness({
      payload: {
        text: "caption",
        mediaUrls: ["https://example.com/1.jpg", "https://example.com/2.jpg"],
      },
      sendResults: [{ messageId: "m-1" }, { messageId: "m-2" }],
    });
    const result = await run();

    expect(sendMock).toHaveBeenCalledTimes(2);
    expect(sendMock).toHaveBeenNthCalledWith(
      1,
      to,
      "caption",
      expect.objectContaining({ mediaUrl: "https://example.com/1.jpg" }),
    );
    expect(sendMock).toHaveBeenNthCalledWith(
      2,
      to,
      "",
      expect.objectContaining({ mediaUrl: "https://example.com/2.jpg" }),
    );
    expect(result).toMatchObject({ channel: params.channel, messageId: "m-2" });
  });

  it("empty payload returns no-op", async () => {
    const { run, sendMock } = params.createHarness({ payload: {} });
    const result = await run();

    expect(sendMock).not.toHaveBeenCalled();
    expect(result).toEqual({ channel: params.channel, messageId: "" });
  });

  if (params.chunking.mode === "passthrough") {
    it("text exceeding chunk limit is sent as-is when chunker is null", async () => {
      const text = "a".repeat(params.chunking.longTextLength);
      const { run, sendMock, to } = params.createHarness({ payload: { text } });
      const result = await run();

      expect(sendMock).toHaveBeenCalledTimes(1);
      expect(sendMock).toHaveBeenCalledWith(to, text, expect.any(Object));
      expect(result).toMatchObject({ channel: params.channel });
    });
    return;
  }

  const chunking = params.chunking;

  it("chunking splits long text", async () => {
    const text = "a".repeat(chunking.longTextLength);
    const { run, sendMock } = params.createHarness({
      payload: { text },
      sendResults: [{ messageId: "c-1" }, { messageId: "c-2" }],
    });
    const result = await run();

    expect(sendMock.mock.calls.length).toBeGreaterThanOrEqual(2);
    for (const call of sendMock.mock.calls) {
      expect((call[1] as string).length).toBeLessThanOrEqual(chunking.maxChunkLength);
    }
    expect(result).toMatchObject({ channel: params.channel });
  });
}

export function primeSendMock(
  sendMock: Mock,
  fallbackResult: Record<string, unknown>,
  sendResults: SendResultLike[] = [],
) {
  sendMock.mockReset();
  if (sendResults.length === 0) {
    sendMock.mockResolvedValue(fallbackResult);
    return;
  }
  for (const result of sendResults) {
    sendMock.mockResolvedValueOnce(result);
  }
}