feat: optional auto reconnect for dropped ssh sessions (#1321)

plugins/ssh-terminal/tests/frontend/terminal/auto-reconnect.test.ts

@@ -0,0 +1,64 @@
+// @vitest-environment node
+import fs from "node:fs";
+import vm from "node:vm";
+import { describe, expect, it, vi } from "vitest";
+
+const source = fs.readFileSync(
+  new URL("../../../src/frontend/terminal/Terminal.tsx", import.meta.url),
+  "utf8",
+);
+const attempt = source.slice(
+  source.indexOf("    function attemptReconnection()"),
+  source.indexOf("    // A persisted session that timed out"),
+);
+
+function run(keepScrollback: boolean, attempts = 0) {
+  const timers: Array<() => void> = [];
+  const context = {
+    terminal: { cols: 100, rows: 30, clear: vi.fn() },
+    hostConfig: { id: 1 },
+    isUnmountingRef: { current: false },
+    shouldNotReconnectRef: { current: false },
+    isReconnectingRef: { current: false },
+    isConnectingRef: { current: false },
+    isAttachingSessionRef: { current: false },
+    wasDisconnectedBySSH: { current: false },
+    reconnectTimeoutRef: { current: null as unknown },
+    reconnectAttempts: { current: attempts },
+    keepScrollbackRef: { current: keepScrollback },
+    maxReconnectAttempts: 8,
+    setIsConnecting: vi.fn(),
+    setShowDisconnectedOverlay: vi.fn(),
+    addLog: vi.fn(),
+    t: (key: string) => key,
+    connectToHost: vi.fn(),
+    setTimeout: (fn: () => void) => {
+      timers.push(fn);
+      return 1;
+    },
+    Math,
+  };
+  vm.runInNewContext(`${attempt}\nattemptReconnection();`, context);
+  timers.forEach((fn) => fn());
+  return context;
+}
+
+describe("terminal auto reconnect", () => {
+  it("keeps the scrollback while reconnecting after a drop", () => {
+    const context = run(true);
+    expect(context.terminal.clear).not.toHaveBeenCalled();
+    expect(context.connectToHost).toHaveBeenCalledWith(100, 30);
+  });
+
+  it("still clears the screen on an ordinary reconnect", () => {
+    const context = run(false);
+    expect(context.terminal.clear).toHaveBeenCalled();
+  });
+
+  it("gives up after the last attempt and stops keeping scrollback", () => {
+    const context = run(true, 8);
+    expect(context.connectToHost).not.toHaveBeenCalled();
+    expect(context.setShowDisconnectedOverlay).toHaveBeenCalledWith(true);
+    expect(context.keepScrollbackRef.current).toBe(false);
+  });
+});