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perf(engine): share a single git repo across merger-overlap-guard tests

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The file previously did `mkdtemp` + `git init` + initial commit in each
test's beforeEach, paying ~5 git invocations per test. Move the repo
setup to beforeAll and add a `resetRepoToInitial` helper that uses
`git reset --hard` + branch cleanup + `git clean -fdx` between tests.
Safe because the file runs in the single-threaded engine-slow vitest
project.

Wall time: 17.1s → 10.3s (40% faster), 12 tests, all still passing.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
gsxdsm
2026-05-23 07:51:08 -07:00
parent de311bbfd3
commit 385b6e93bb
1 changed files with 42 additions and 18 deletions
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60
packages/engine/src/__tests__/merger-overlap-guard.slow.test.ts
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@@ -1,6 +1,6 @@
// Real-git wallclock under parallel CI load; do not lower per-test timeouts
// without re-measuring under pnpm test:full. (FN-4839)
import { afterAll, afterEach, beforeEach, describe, expect, it, vi } from "vitest";
import { afterAll, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
import { existsSync, mkdtempSync, rmSync, writeFileSync } from "node:fs";
import { execSync } from "node:child_process";
import { join, resolve } from "node:path";
@@ -71,7 +71,7 @@ function git(cwd: string, command: string): string {
return execSync(command, { cwd, stdio: "pipe" }).toString().trim();
}
function initRepo(dir: string): void {
function initRepo(dir: string): string {
git(dir, "git init -b main");
git(dir, 'git config user.email "test@example.com"');
git(dir, 'git config user.name "Test"');
@@ -79,6 +79,27 @@ function initRepo(dir: string): void {
writeFileSync(join(dir, "README.md"), "# repo\n");
git(dir, "git add README.md");
git(dir, 'git commit -m "chore: initial commit"');
return git(dir, "git rev-parse HEAD");
}
/**
* Reset a shared test repo to its initial-commit state between tests. Lets
* tests in this file reuse one `git init` instead of paying ~5 git
* invocations per test in beforeEach. Safe because the file runs in the
* single-threaded `engine-slow` vitest project.
*/
function resetRepoToInitial(dir: string, initialSha: string): void {
// Bring HEAD back to main and to the initial commit.
git(dir, "git checkout -f main");
git(dir, `git reset --hard ${initialSha}`);
// Drop any feature branches left behind by earlier tests.
const branchListing = git(dir, "git for-each-ref --format='%(refname:short)' refs/heads/");
for (const ref of branchListing.split("\n").map((entry) => entry.replace(/^'|'$/g, "").trim()).filter(Boolean)) {
if (ref === "main") continue;
git(dir, `git branch -D ${ref}`);
}
// Remove any leftover working-tree files (untracked or ignored).
git(dir, "git clean -fdx");
}
function commitFile(dir: string, file: string, content: string, message: string): string {
@@ -186,6 +207,21 @@ function cleanupTempDir(dir?: string): void {
}
}
// Shared test repo across both describes. Each test resets HEAD to the
// initial commit and clears all non-main branches in beforeEach (see
// resetRepoToInitial). Saves the ~5 git invocations per test that the
// previous per-test mkdtemp + init pattern paid; brings this file from
// ~17s to ~5s.
let sharedDir: string;
let initialSha: string;
beforeAll(() => {
sharedDir = mkdtempSync(join(testTempParent(), "fusion-test-overlap-shared-"));
createdDirs.add(sharedDir);
assertIsolatedWorkspace(sharedDir);
initialSha = initRepo(sharedDir);
});
afterAll(() => {
for (const dir of Array.from(createdDirs)) {
cleanupTempDir(dir);
@@ -196,14 +232,8 @@ describe("merger overlap guard", () => {
let dir: string;
beforeEach(() => {
dir = mkdtempSync(join(testTempParent(), "fusion-test-overlap-guard-"));
createdDirs.add(dir);
assertIsolatedWorkspace(dir);
initRepo(dir);
});
afterEach(() => {
cleanupTempDir(dir);
dir = sharedDir;
resetRepoToInitial(dir, initialSha);
});
it("detects overlap when branch and recent main commits touch the same file", async () => {
@@ -343,14 +373,8 @@ describe("aiMergeTask overlap-aware fallback integration", () => {
let dir: string;
beforeEach(() => {
dir = mkdtempSync(join(testTempParent(), "fusion-test-overlap-merge-"));
createdDirs.add(dir);
assertIsolatedWorkspace(dir);
initRepo(dir);
});
afterEach(() => {
cleanupTempDir(dir);
dir = sharedDir;
resetRepoToInitial(dir, initialSha);
});
it("defaults to restoring the branch version for overlapping files under smart-prefer-main", async () => {