perf(test): speed up config tests

src/config/config.backup-rotation.test.ts

@@ -1,20 +1,35 @@
 import fs from "node:fs/promises";
+import path from "node:path";
 import { describe, expect, it } from "vitest";
 import type { OpenClawConfig } from "./types.js";
+import { rotateConfigBackups } from "./backup-rotation.js";
 import { withTempHome } from "./test-helpers.js";
 
 describe("config backup rotation", () => {
   it("keeps a 5-deep backup ring for config writes", async () => {
     await withTempHome(async () => {
-      const { resolveConfigPath, writeConfigFile } = await import("./config.js");
-      const configPath = resolveConfigPath();
+      const stateDir = process.env.OPENCLAW_STATE_DIR?.trim();
+      if (!stateDir) {
+        throw new Error("Expected OPENCLAW_STATE_DIR to be set by withTempHome");
+      }
+      const configPath = path.join(stateDir, "openclaw.json");
       const buildConfig = (version: number): OpenClawConfig =>
         ({
           agents: { list: [{ id: `v${version}` }] },
         }) as OpenClawConfig;
 
-      for (let version = 0; version <= 6; version += 1) {
-        await writeConfigFile(buildConfig(version));
+      const writeVersion = async (version: number) => {
+        const json = JSON.stringify(buildConfig(version), null, 2).trimEnd().concat("\n");
+        await fs.writeFile(configPath, json, "utf-8");
+      };
+
+      await writeVersion(0);
+      for (let version = 1; version <= 6; version += 1) {
+        await rotateConfigBackups(configPath, fs);
+        await fs.copyFile(configPath, `${configPath}.bak`).catch(() => {
+          // best-effort
+        });
+        await writeVersion(version);
       }
 
       const readName = async (suffix = "") => {