test(FN-4383): complete Step 3 — add real-git base commit capture regression

Fusion-Task-Id: FN-4383
Fusion-Task-Lineage: 69516bdf-34d1-405c-8bc9-b558c4780863

packages/engine/src/__tests__/executor-base-commit-capture.real-git.test.ts

@@ -0,0 +1,82 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { execSync, spawnSync } from "node:child_process";
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { EventEmitter } from "node:events";
+import type { Task, TaskStore } from "@fusion/core";
+import { TaskExecutor } from "../executor.js";
+
+const hasGit = spawnSync("git", ["--version"], { stdio: "pipe" }).status === 0;
+const describeIfGit = hasGit ? describe : describe.skip;
+
+function git(repo: string, command: string): string {
+  return execSync(command, { cwd: repo, encoding: "utf-8", stdio: ["pipe", "pipe", "pipe"] }).trim();
+}
+
+function createStore(): TaskStore & EventEmitter {
+  const emitter = new EventEmitter();
+  return Object.assign(emitter, {
+    updateTask: vi.fn().mockResolvedValue(undefined),
+    on: emitter.on.bind(emitter),
+  }) as unknown as TaskStore & EventEmitter;
+}
+
+function makeTask(baseCommitSha?: string): Task {
+  return {
+    id: "FN-TEST-4383",
+    title: "Test",
+    description: "Test",
+    column: "in-progress",
+    dependencies: [],
+    steps: [],
+    currentStep: 0,
+    log: [],
+    createdAt: new Date().toISOString(),
+    updatedAt: new Date().toISOString(),
+    ...(baseCommitSha ? { baseCommitSha } : {}),
+  } as Task;
+}
+
+describeIfGit("captureBaseCommitSha (real git)", () => {
+  const repos: string[] = [];
+
+  afterEach(() => {
+    for (const repo of repos.splice(0)) rmSync(repo, { recursive: true, force: true });
+  });
+
+  it("FN-4309/FN-4383: preserves baseCommitSha across sessions and keeps commit distance", async () => {
+    const repo = mkdtempSync(path.join(os.tmpdir(), "fn-4383-"));
+    repos.push(repo);
+    git(repo, "git init -b main");
+    git(repo, 'git config user.email "test@example.com"');
+    git(repo, 'git config user.name "Test"');
+
+    writeFileSync(path.join(repo, "file.txt"), "init\n", "utf-8");
+    git(repo, "git add file.txt && git commit -m 'init'");
+
+    git(repo, "git checkout -b fusion/fn-test-4383");
+    for (let i = 1; i <= 17; i += 1) {
+      writeFileSync(path.join(repo, `branch-${i}.txt`), `branch ${i}\n`, "utf-8");
+      git(repo, `git add branch-${i}.txt && git commit -m 'branch ${i}'`);
+    }
+
+    const store = createStore();
+    const executor = new TaskExecutor(store, repo);
+    const audit = { git: vi.fn().mockResolvedValue(undefined) };
+
+    await (executor as any).captureBaseCommitSha(makeTask(), repo, audit);
+    const firstBase = (store.updateTask as any).mock.calls[0][1].baseCommitSha as string;
+    expect(firstBase).toBeTruthy();
+
+    writeFileSync(path.join(repo, "branch-18.txt"), "branch 18\n", "utf-8");
+    git(repo, "git add branch-18.txt && git commit -m 'branch 18'");
+
+    await (executor as any).captureBaseCommitSha(makeTask(firstBase), repo, audit);
+
+    expect((store.updateTask as any).mock.calls).toHaveLength(1);
+
+    const distance = Number(git(repo, `git rev-list --count ${firstBase}..HEAD`));
+    expect(distance).toBeGreaterThan(0);
+  });
+});