Add deterministic-tests (#190)

Reviewed-on: https://home.schmelczer.dev/git/git/andras/vault-link/pulls/190
Co-authored-by: Andras Schmelczer <andras@schmelczer.dev>
Co-committed-by: Andras Schmelczer <andras@schmelczer.dev>

frontend/deterministic-tests/src/server-manager.ts

@@ -0,0 +1,71 @@
+import type { ServerControl } from "./server-control";
+import type { Logger } from "sync-client";
+
+export class ServerManager {
+    private readonly activeServers = new Set<ServerControl>();
+    private readonly logger: Logger;
+    private isShuttingDown = false;
+
+    public constructor(logger: Logger) {
+        this.logger = logger;
+    }
+
+    public track(server: ServerControl): void {
+        this.activeServers.add(server);
+    }
+
+    public untrack(server: ServerControl): void {
+        this.activeServers.delete(server);
+    }
+
+    public async stopAll(): Promise<void> {
+        if (this.isShuttingDown) {
+            return;
+        }
+        this.isShuttingDown = true;
+
+        const servers = Array.from(this.activeServers);
+        // eslint-disable-next-line no-restricted-properties
+        await Promise.all(
+            servers.map(async (server) => {
+                try {
+                    await server.stop();
+                } catch {
+                    // Best-effort cleanup during shutdown
+                }
+            })
+        );
+    }
+
+    public installSignalHandlers(): void {
+        process.on("SIGINT", () => {
+            this.logger.info("Received SIGINT, shutting down...");
+            void this.stopAll()
+                .catch(() => {
+                    /* no-op */
+                })
+                .then(() => process.exit(130));
+        });
+
+        process.on("SIGTERM", () => {
+            this.logger.info("Received SIGTERM, shutting down...");
+            void this.stopAll()
+                .catch(() => {
+                    /* no-op */
+                })
+                .then(() => process.exit(143));
+        });
+
+        // Last-resort synchronous cleanup. Runs even when the process is
+        // exiting via process.exit() from unhandledRejection /
+        // uncaughtException — paths where async stopAll() cannot complete.
+        // SIGSTOP'd servers MUST receive SIGCONT before SIGKILL or the
+        // kernel keeps them as zombies holding the test's tmpdir, and the
+        // next CI run can't reuse the port.
+        process.on("exit", () => {
+            for (const server of this.activeServers) {
+                server.forceKillSync();
+            }
+        });
+    }
+}