deer-flow/frontend/tests/unit/core/mcp/hooks.test.ts

import { beforeEach, describe, expect, it, rs } from "@rstest/core";
import { QueryClient } from "@tanstack/react-query";
import { toast } from "sonner";

rs.mock("@/core/api/fetcher", () => ({
  fetch: rs.fn(),
}));

rs.mock("sonner", () => ({
  toast: {
    error: rs.fn(),
  },
}));

import { fetch } from "@/core/api/fetcher";
import { MCPConfigRequestError, loadMCPConfig } from "@/core/mcp/api";
import { getEnableMCPServerMutationOptions } from "@/core/mcp/hooks";

const mockedFetch = rs.mocked(fetch);
const mockedToastError = rs.mocked(toast.error);

function makeClient() {
  return new QueryClient({
    defaultOptions: {
      queries: {
        retryDelay: 0,
      },
    },
  });
}

describe("useMCPConfig retry policy", () => {
  beforeEach(() => {
    mockedFetch.mockReset();
    mockedToastError.mockReset();
  });

  it("does not retry when loadMCPConfig throws MCPConfigRequestError (403)", async () => {
    mockedFetch.mockResolvedValue({
      ok: false,
      status: 403,
      json: async () => ({ detail: "Forbidden" }),
    } as Response);

    const client = makeClient();
    await expect(
      client.fetchQuery({
        queryKey: ["mcpConfig"],
        queryFn: () => loadMCPConfig(),
        retry: (count, error) =>
          !(error instanceof MCPConfigRequestError) && count < 3,
      }),
    ).rejects.toBeInstanceOf(MCPConfigRequestError);

    expect(mockedFetch).toHaveBeenCalledTimes(1);
  });

  it("retries up to 3 times on generic errors", async () => {
    mockedFetch.mockRejectedValue(new Error("network down"));

    const client = makeClient();
    await expect(
      client.fetchQuery({
        queryKey: ["mcpConfig"],
        queryFn: () => loadMCPConfig(),
        retry: (count, error) =>
          !(error instanceof MCPConfigRequestError) && count < 3,
      }),
    ).rejects.toThrow("network down");

    // initial + 3 retries = 4 calls
    expect(mockedFetch).toHaveBeenCalledTimes(4);
  });

  it("does not retry on MCPConfigRequestError 5xx either (deterministic typed error)", async () => {
    mockedFetch.mockResolvedValue({
      ok: false,
      status: 500,
      json: async () => ({ detail: "Boom" }),
    } as Response);

    const client = makeClient();
    await expect(
      client.fetchQuery({
        queryKey: ["mcpConfig"],
        queryFn: () => loadMCPConfig(),
        retry: (count, error) =>
          !(error instanceof MCPConfigRequestError) && count < 3,
      }),
    ).rejects.toBeInstanceOf(MCPConfigRequestError);

    expect(mockedFetch).toHaveBeenCalledTimes(1);
  });
});

describe("MCP server state mutation", () => {
  beforeEach(() => {
    mockedFetch.mockReset();
    mockedToastError.mockReset();
  });

  it("invalidates MCP config after a successful targeted update", async () => {
    mockedFetch.mockResolvedValue(
      new Response(JSON.stringify({ mcp_servers: {} }), { status: 200 }),
    );
    const client = makeClient();
    const invalidateQueries = rs
      .spyOn(client, "invalidateQueries")
      .mockResolvedValue();
    const mutation = client
      .getMutationCache()
      .build(client, getEnableMCPServerMutationOptions(client));

    await mutation.execute({ serverName: "github", enabled: false });

    expect(invalidateQueries).toHaveBeenCalledWith({
      queryKey: ["mcpConfig"],
    });
    expect(mockedToastError).not.toHaveBeenCalled();
  });

  it("shows the backend error detail when a targeted update fails", async () => {
    const detail =
      "MCP server 'semantic-scholar' uses disallowed stdio command 's2-mcp-server'.";
    mockedFetch.mockResolvedValue(
      new Response(JSON.stringify({ detail }), { status: 400 }),
    );
    const client = makeClient();
    const invalidateQueries = rs.spyOn(client, "invalidateQueries");
    const mutation = client
      .getMutationCache()
      .build(client, getEnableMCPServerMutationOptions(client));

    await expect(
      mutation.execute({ serverName: "semantic-scholar", enabled: true }),
    ).rejects.toThrow(detail);

    expect(mockedToastError).toHaveBeenCalledWith(detail);
    expect(invalidateQueries).not.toHaveBeenCalled();
  });
});