fix: harden onboarding for non-systemd environments

src/daemon/systemd-availability.test.ts

@@ -0,0 +1,35 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const execFileMock = vi.hoisted(() => vi.fn());
+
+vi.mock("node:child_process", () => ({
+  execFile: execFileMock,
+}));
+
+import { isSystemdUserServiceAvailable } from "./systemd.js";
+
+describe("systemd availability", () => {
+  beforeEach(() => {
+    execFileMock.mockReset();
+  });
+
+  it("returns true when systemctl --user succeeds", async () => {
+    execFileMock.mockImplementation((_cmd, _args, _opts, cb) => {
+      cb(null, "", "");
+    });
+    await expect(isSystemdUserServiceAvailable()).resolves.toBe(true);
+  });
+
+  it("returns false when systemd user bus is unavailable", async () => {
+    execFileMock.mockImplementation((_cmd, _args, _opts, cb) => {
+      const err = new Error("Failed to connect to bus") as Error & {
+        stderr?: string;
+        code?: number;
+      };
+      err.stderr = "Failed to connect to bus";
+      err.code = 1;
+      cb(err, "", "");
+    });
+    await expect(isSystemdUserServiceAvailable()).resolves.toBe(false);
+  });
+});