reverse-engineering-anything/tests/boundary/mcp/javascriptRuntimeObservationMcp.test.ts

import { rm, writeFile } from "node:fs/promises";
import { join } from "node:path";
import { pathToFileURL } from "node:url";

import { Client, InMemoryTransport } from "@modelcontextprotocol/client";
import { afterEach, describe, expect, test } from "vitest";

import { createTestBinarySession } from "../../fixtures/binarySession.js";
import { observeJavaScriptRuntime } from "../../../src/application/JavaScriptRuntimeObservationService.js";
import { V8InspectorProvider } from "../../../src/browser/V8InspectorProvider.js";
import {
  javascriptRuntimeObservationSchema,
  javascriptRuntimeTargetListSchema,
  observeJavaScriptRuntimeInputSchema,
} from "../../../src/domain/javascriptRuntimeObservation.js";
import { createServer } from "../../../src/server/createServer.js";
import { observed } from "../../fixtures/analysisExecution.js";
import { startFakeV8Inspector } from "../../fixtures/fakeV8Inspector.js";
import { createTestTempDirectory } from "../../fixtures/temporaryDirectory.js";

describe("JavaScript runtime observation MCP tools", () => {
  const resources: Array<{ close(): Promise<unknown> }> = [];
  const temporary: string[] = [];

  afterEach(async () => {
    await Promise.all(resources.splice(0).map((item) => item.close()));
    await Promise.all(
      temporary
        .splice(0)
        .map((path) => rm(path, { recursive: true, force: true })),
    );
  });

  test("accepts long caller windows and complete observation metadata", () => {
    const repeated = (count: number): string[] =>
      Array.from({ length: count }, (_, index) => `item-${index}`);
    const scope = {
      inspector_endpoint: "http://127.0.0.1:9222",
    };
    expect(
      observeJavaScriptRuntimeInputSchema.parse({
        ...scope,
        target_id: "target",
        observation_ms: 2_147_483_648,
      }).observation_ms,
    ).toBe(2_147_483_648);
    expect(
      javascriptRuntimeTargetListSchema.parse({
        runtime: {
          product: "Node.js",
          protocol_version: "1.0",
          v8_version: null,
        },
        targets: [],
        excluded: {
          unsupported_location: 0,
          unconnectable: 0,
        },
        limitations: repeated(101),
      }).limitations,
    ).toHaveLength(101);

    const unknowns = repeated(101);
    const limitations = repeated(101);
    expect(
      javascriptRuntimeObservationSchema.parse({
        runtime: {
          product: "Node.js",
          protocol_version: "1.0",
          v8_version: null,
        },
        target: {
          target_id: "target",
          protocol_type: "node",
          attached: false,
          location: { kind: "file", file_path: "/tmp/rea-runtime/main.js" },
          runtime_kind: "node",
          runtime_kind_authority: "caller-declared-unverified",
        },
        capture: {
          observation_ms: 10_001,
          events_observed: 0,
          events_retained: 0,
          events_dropped: 0,
          metadata_bytes_retained: 0,
          truncated: false,
          truncation_reasons: repeated(21),
        },
        scripts: {
          items: [],
          observed_total: 0,
          excluded: {
            unsupported_location: 0,
            invalid_protocol_value: 0,
          },
        },
        execution_contexts: [],
        directly_observed: repeated(21),
        unavailable_without_instrumentation: repeated(21),
        unknowns,
        limitations,
      }),
    ).toMatchObject({ unknowns, limitations });
  });

  test("lists and observes one target as retained Evidence", async () => {
    const root = await createTestTempDirectory("rea-v8-mcp-");
    temporary.push(root);
    const { entry, inspector, client } = await createObservationClient(
      root,
      resources,
    );

    const listed = await client.callTool({
      name: "list_javascript_runtime_targets",
      arguments: {
        inspector_endpoint: inspector.endpoint,
      },
    });
    expect(listed.isError).not.toBe(true);
    expect(listed.structuredContent).toMatchObject({
      result: {
        targets: [{ target_id: inspector.targetId }],
      },
    });
    const observedRuntime = await client.callTool({
      name: "observe_javascript_runtime",
      arguments: {
        inspector_endpoint: inspector.endpoint,
        target_id: inspector.targetId,
        runtime_kind: "node",
        observation_ms: 10,
      },
    });
    expect(observedRuntime.isError).not.toBe(true);
    expect(observedRuntime.structuredContent).toMatchObject({
      result: {
        target: {
          target_id: inspector.targetId,
          runtime_kind: "node",
          runtime_kind_authority: "caller-declared-unverified",
        },
        scripts: {
          items: [
            expect.objectContaining({
              location: { kind: "file", file_path: entry },
            }),
          ],
        },
      },
    });
    const evidenceId = evidenceIdFrom(observedRuntime.structuredContent);
    expect(observedRuntime.structuredContent).toMatchObject({
      evidence: {
        evidence_id: evidenceId,
        operation: "observe_javascript_runtime",
        parameters: expect.any(Object),
      },
    });
    expect(new Set(inspector.commands.map(({ method }) => method))).toEqual(
      new Set(["Runtime.enable", "Debugger.enable"]),
    );
    const direct = await observeDirectly(inspector);
    expect(direct.ok).toBe(true);
    if (direct.ok) expect(evidenceId).toBe(direct.value.evidence_id);
  });
});

const createObservationClient = async (
  root: string,
  resources: Array<{ close(): Promise<unknown> }>,
) => {
  const entry = join(root, "entry.js");
  await writeFile(entry, "export const value = 1;\n");
  const inspector = await startFakeV8Inspector({
    targetUrl: pathToFileURL(entry).href,
  });
  resources.push(inspector);
  const session = createTestBinarySession(() => ({
    execute: () => Promise.resolve(observed(null)),
    close: () => Promise.resolve(),
  }));
  const server = createServer(session, session, {
    javascriptRuntimeObservation: new V8InspectorProvider(),
    availabilityPolicy: () => ({
      processCaptureEnabled: false,
      investigationInputRoots: 0,
    }),
  });
  const client = new Client({ name: "v8-mcp-test", version: "1" });
  const [clientTransport, serverTransport] =
    InMemoryTransport.createLinkedPair();
  resources.push(client, server, session);
  await server.connect(serverTransport);
  await client.connect(clientTransport);
  return { entry, inspector, client };
};

const observeDirectly = (
  inspector: Awaited<ReturnType<typeof startFakeV8Inspector>>,
) =>
  observeJavaScriptRuntime(
    new V8InspectorProvider(),
    observeJavaScriptRuntimeInputSchema.parse({
      inspector_endpoint: inspector.endpoint,
      target_id: inspector.targetId,
      runtime_kind: "node",
      observation_ms: 10,
    }),
  );

const evidenceIdFrom = (value: unknown): string => {
  if (typeof value !== "object" || value === null)
    throw new TypeError("Missing structured result");
  const evidenceId = Reflect.get(value, "evidence_id");
  if (typeof evidenceId !== "string")
    throw new TypeError("Missing Evidence ID");
  return evidenceId;
};