test(process): make Linux adapter wiring portable (#120741)

Co-authored-by: Peter Steinberger <steipete@openai.com>

src/process/supervisor/adapters/child.test.ts

@@ -10,6 +10,7 @@ import { useAutoCleanupTempDirTracker } from "../../../../test/helpers/temp-dir.
 import {
   expectRealExitWinsOverSigkillFallback,
   expectWaitStaysPendingUntilSigkillFallback,
+  mockLinuxOomWrapperShell,
 } from "./test-support.js";
 
 const { spawnWithFallbackMock, signalProcessTreeMock, createWindowsOutputDecoderMock } = vi.hoisted(
@@ -742,6 +743,7 @@ describe("createChildAdapter", () => {
     const originalEnv = process.env.ENV;
     const originalCdpath = process.env.CDPATH;
     setPlatform("linux");
+    const restoreLinuxShell = mockLinuxOomWrapperShell();
     process.env.BASH_ENV = "/tmp/bashenv";
     process.env.ENV = "/tmp/env";
     process.env.CDPATH = "/tmp";
@@ -752,6 +754,7 @@ describe("createChildAdapter", () => {
       });
       expect(adapter.oomScoreWrapperSelected).toBe(true);
     } finally {
+      restoreLinuxShell();
       if (originalBashEnv === undefined) {
         delete process.env.BASH_ENV;
       } else {

src/process/supervisor/adapters/pty.test.ts

@@ -3,6 +3,7 @@ import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "vite
 import {
   expectRealExitWinsOverSigkillFallback,
   expectWaitStaysPendingUntilSigkillFallback,
+  mockLinuxOomWrapperShell,
 } from "./test-support.js";
 
 const { spawnMock, ptyKillMock, signalProcessTreeMock } = vi.hoisted(() => ({
@@ -157,7 +158,7 @@ describe("createPtyAdapter", () => {
 
   it("forwards non-SIGTERM explicit signals to node-pty kill on non-Windows", async () => {
     const originalPlatform = Object.getOwnPropertyDescriptor(process, "platform");
-    Object.defineProperty(process, "platform", { value: "linux", configurable: true });
+    Object.defineProperty(process, "platform", { value: "darwin", configurable: true });
     try {
       spawnMock.mockReturnValue(createStubPty());
 
@@ -316,17 +317,21 @@ describe("createPtyAdapter", () => {
   it("wraps Linux PTY spawns so shell children inherit higher OOM score", async () => {
     const originalPlatform = Object.getOwnPropertyDescriptor(process, "platform");
     Object.defineProperty(process, "platform", { value: "linux", configurable: true });
+    const restoreLinuxShell = mockLinuxOomWrapperShell();
+    vi.resetModules();
     try {
+      const { createPtyAdapter: createLinuxPtyAdapter } = await import("./pty.js");
       const stub = createStubPty();
       spawnMock.mockReturnValue(stub);
 
-      const adapter = await createPtyAdapter({
+      const adapter = await createLinuxPtyAdapter({
         shell: "bash",
         args: ["-lc", "env"],
         env: { PATH: "/usr/bin", BASH_ENV: "/tmp/bashenv", TERM: "dumb" },
       });
       expect(adapter.oomScoreWrapperSelected).toBe(true);
     } finally {
+      restoreLinuxShell();
       if (originalPlatform) {
         Object.defineProperty(process, "platform", originalPlatform);
       }

src/process/supervisor/adapters/test-support.ts

@@ -1,4 +1,5 @@
 // Supervisor adapter test support builds mock process handles for adapter tests.
+import fs from "node:fs";
 import { expect, vi } from "vitest";
 
 /**
@@ -11,6 +12,22 @@ type WaitResult = {
   signal: number | NodeJS.Signals | null;
 };
 
+/** Keep Linux adapter wiring tests deterministic on hosts without `/bin/sh`. */
+export function mockLinuxOomWrapperShell(): () => void {
+  const statSync = fs.statSync.bind(fs);
+  const fileStats = statSync(process.execPath);
+  const statSyncMock = vi
+    .spyOn(fs, "statSync")
+    .mockImplementation((target, options) =>
+      String(target) === "/bin/sh" ? fileStats : statSync(target, options as never),
+    );
+  return () => {
+    statSyncMock.mockRestore();
+    // The production helper memoizes shell availability; clear it for later tests.
+    vi.resetModules();
+  };
+}
+
 /** Assert fallback SIGKILL resolves only after the grace timer expires. */
 export async function expectWaitStaysPendingUntilSigkillFallback(
   waitPromise: Promise<WaitResult>,