Add failing repro: a timed-out background fetch leaves a partial pack (#3335)

packages/server/src/server/workspace-git-fetch-timeout.local.e2e.test.ts

@@ -0,0 +1,120 @@
+import { execFileSync } from "node:child_process";
+import { mkdtempSync, readdirSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { randomBytes } from "node:crypto";
+
+import { afterAll, beforeAll, expect, test } from "vitest";
+
+import { runGitCommand, type RunGitCommand } from "../utils/run-git-command.js";
+import { fetchWorkspaceGitRemote } from "./workspace-git-fetch.js";
+
+// Repro for #3335: a background fetch that outlives its timeout is SIGKILLed,
+// and every killed attempt leaves a partial `tmp_pack_*` behind. The daemon
+// retries every 180s, so a fetch that needs longer than the timeout grows
+// `.git/objects/pack` without bound.
+
+const FETCH_TIMEOUT_MS = 300;
+const cleanupPaths: string[] = [];
+let checkout: string;
+
+function git(cwd: string, args: string[]): string {
+  return execFileSync("git", args, {
+    cwd,
+    encoding: "utf8",
+    env: { ...process.env, GIT_CONFIG_NOSYSTEM: "1", GIT_TERMINAL_PROMPT: "0" },
+  }).trim();
+}
+
+beforeAll(() => {
+  const root = mkdtempSync(join(tmpdir(), "paseo-fetch-timeout-"));
+  cleanupPaths.push(root);
+  const upstream = join(root, "upstream.git");
+  const seed = join(root, "seed");
+  checkout = join(root, "checkout");
+  git(root, ["init", "-q", "--bare", "-b", "main", upstream]);
+  git(root, ["init", "-q", "-b", "main", seed]);
+  git(seed, [
+    "-c",
+    "user.name=t",
+    "-c",
+    "user.email=t@t",
+    "commit",
+    "-q",
+    "--allow-empty",
+    "-m",
+    "init",
+  ]);
+  git(seed, ["push", "-q", upstream, "main"]);
+  git(root, ["clone", "-q", "--no-local", upstream, checkout]);
+  // Advance upstream with incompressible content so the next fetch takes
+  // longer than FETCH_TIMEOUT_MS to transfer. More than git's default
+  // `fetch.unpackLimit` (100 objects) so the fetch keeps a pack, like any
+  // large fetch does, instead of exploding into loose objects.
+  for (let i = 0; i < 200; i += 1) {
+    writeFileSync(join(seed, `blob-${i}.bin`), randomBytes(1024 * 1024));
+  }
+  git(seed, ["add", "."]);
+  git(seed, [
+    "-c",
+    "user.name=t",
+    "-c",
+    "user.email=t@t",
+    "commit",
+    "-q",
+    "-m",
+    "large",
+  ]);
+  git(seed, ["push", "-q", upstream, "main"]);
+}, 120_000);
+
+afterAll(() => {
+  for (const path of cleanupPaths.splice(0)) {
+    rmSync(path, { recursive: true, force: true });
+  }
+});
+
+function packDirectory(): { tmpPacks: string[] } {
+  const entries = readdirSync(join(checkout, ".git", "objects", "pack"));
+  return { tmpPacks: entries.filter((entry) => entry.startsWith("tmp_pack_")) };
+}
+
+// The daemon's runner, with the fetch budget shortened from 120s so a local
+// fetch outlives it the way a large repository's fetch outlives 120s.
+const runWithShortFetchTimeout: RunGitCommand = (args, options) =>
+  runGitCommand(
+    args,
+    args[0] === "fetch" ? { ...options, timeout: FETCH_TIMEOUT_MS } : options
+  );
+
+test("a background fetch that times out leaves no partial pack behind", async () => {
+  const before = packDirectory();
+  const observations: { error: string | null; tmpPacks: number }[] = [];
+  for (let attempt = 0; attempt < 3; attempt += 1) {
+    const result = await fetchWorkspaceGitRemote(
+      checkout,
+      { onRefSnapshot() {} },
+      runWithShortFetchTimeout
+    );
+    const after = packDirectory();
+    observations.push({
+      error: result.error instanceof Error ? result.error.message : null,
+      tmpPacks: after.tmpPacks.length,
+    });
+  }
+
+  expect(observations).toEqual([
+    {
+      error: expect.stringContaining("timed out"),
+      tmpPacks: before.tmpPacks.length,
+    },
+    {
+      error: expect.stringContaining("timed out"),
+      tmpPacks: before.tmpPacks.length,
+    },
+    {
+      error: expect.stringContaining("timed out"),
+      tmpPacks: before.tmpPacks.length,
+    },
+  ]);
+}, 60_000);