test(FN-4114): complete Step 4 — add invariant and liveness regression tests

Fusion-Task-Id: FN-4114
Fusion-Task-Lineage: 44fd5718-42dc-44d1-8f5a-97b67dd05d13

packages/engine/src/__tests__/executor-task-done-invariant.test.ts

@@ -0,0 +1,111 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import "./executor-test-helpers.js";
+import { TaskExecutor } from "../executor.js";
+import * as worktreePool from "../worktree-pool.js";
+import { createMockStore, mockedCreateFnAgent, mockedExecSync, resetExecutorMocks } from "./executor-test-helpers.js";
+
+function baseTask(overrides: Record<string, unknown> = {}) {
+  return {
+    id: "FN-4114",
+    title: "Invariant test",
+    description: "",
+    column: "in-progress",
+    worktree: "/repo/.worktrees/swift-falcon",
+    branch: "fusion/fn-4114",
+    baseCommitSha: "abc123",
+    taskDoneRetryCount: 0,
+    steps: [{ name: "Step 1", status: "in-progress" as const }],
+    currentStep: 0,
+    dependencies: [],
+    createdAt: new Date().toISOString(),
+    updatedAt: new Date().toISOString(),
+    ...overrides,
+  };
+}
+
+async function setup(overrides: Record<string, unknown> = {}) {
+  const store = createMockStore();
+  let task: any = baseTask(overrides);
+  let tool: any;
+
+  store.getTask.mockImplementation(async () => ({ ...task, steps: task.steps.map((s: any) => ({ ...s })) }));
+  store.moveTask.mockImplementation(async (id: string, column: string) => {
+    task = { ...task, id, column, paused: false, pausedByAgentId: null, status: null, error: null };
+  });
+
+  mockedCreateFnAgent.mockImplementation(async ({ customTools }: any) => {
+    tool = customTools.find((t: any) => t.name === "fn_task_done");
+    return { session: { prompt: vi.fn().mockResolvedValue(undefined), dispose: vi.fn() } } as any;
+  });
+
+  const executor = new TaskExecutor(store as any, "/repo");
+  await executor.execute(baseTask() as any);
+
+  return { store, tool, setTask: (next: any) => (task = { ...task, ...next }) };
+}
+
+describe("FN-4114 fn_task_done invariants", () => {
+  beforeEach(() => {
+    resetExecutorMocks();
+    vi.spyOn(worktreePool, "isUsableTaskWorktree").mockResolvedValue(true);
+    mockedExecSync.mockImplementation((cmd: string) => {
+      if (cmd.includes("rev-parse --show-toplevel")) return Buffer.from("/repo/.worktrees/swift-falcon\n");
+      if (cmd.includes("rev-parse --abbrev-ref HEAD")) return Buffer.from("fusion/fn-4114\n");
+      if (cmd.includes("rev-list --count")) return Buffer.from("1\n");
+      if (cmd.includes("rev-parse HEAD")) return Buffer.from("def456\n");
+      return Buffer.from("");
+    });
+  });
+
+  it("FN-4114 refuses fn_task_done when toplevel resolves to repo root", async () => {
+    const { store, tool } = await setup();
+    mockedExecSync.mockImplementation((cmd: string) => {
+      if (cmd.includes("rev-parse --show-toplevel")) return Buffer.from("/repo\n");
+      if (cmd.includes("rev-parse --abbrev-ref HEAD")) return Buffer.from("fusion/fn-4114\n");
+      if (cmd.includes("rev-list --count")) return Buffer.from("1\n");
+      if (cmd.includes("rev-parse HEAD")) return Buffer.from("def456\n");
+      return Buffer.from("");
+    });
+
+    const result = await tool.execute("id", {});
+    expect(result.content[0].text).toContain("fn_task_done refused: wrong_toplevel");
+    expect(store.updateStep).not.toHaveBeenCalled();
+    expect(store.moveTask).toHaveBeenCalledWith("FN-4114", "todo", { preserveProgress: true });
+  });
+
+  it("FN-4114 refuses fn_task_done when branch is wrong", async () => {
+    const { store, tool } = await setup();
+    mockedExecSync.mockImplementation((cmd: string) => {
+      if (cmd.includes("rev-parse --show-toplevel")) return Buffer.from("/repo/.worktrees/swift-falcon\n");
+      if (cmd.includes("rev-parse --abbrev-ref HEAD")) return Buffer.from("main\n");
+      if (cmd.includes("rev-parse HEAD")) return Buffer.from("def456\n");
+      return Buffer.from("");
+    });
+
+    const result = await tool.execute("id", {});
+    expect(result.content[0].text).toContain("fn_task_done refused: wrong_branch");
+    expect(store.moveTask).toHaveBeenCalledWith("FN-4114", "todo", { preserveProgress: true });
+  });
+
+  it("FN-4114 refuses fn_task_done when no commits exist beyond base", async () => {
+    const { store, tool } = await setup();
+    mockedExecSync.mockImplementation((cmd: string) => {
+      if (cmd.includes("rev-parse --show-toplevel")) return Buffer.from("/repo/.worktrees/swift-falcon\n");
+      if (cmd.includes("rev-parse --abbrev-ref HEAD")) return Buffer.from("fusion/fn-4114\n");
+      if (cmd.includes("rev-list --count")) return Buffer.from("0\n");
+      if (cmd.includes("rev-parse HEAD")) return Buffer.from("def456\n");
+      return Buffer.from("");
+    });
+
+    const result = await tool.execute("id", {});
+    expect(result.content[0].text).toContain("fn_task_done refused: no_commits");
+    expect(store.moveTask).toHaveBeenCalledWith("FN-4114", "todo", { preserveProgress: true });
+  });
+
+  it("FN-4114 allows fn_task_done on valid worktree/branch/commit state", async () => {
+    const { store, tool } = await setup();
+    const result = await tool.execute("id", {});
+    expect(result.content[0].text).toContain("Task marked complete");
+    expect(store.updateStep).toHaveBeenCalled();
+  });
+});