feat(notifications): add overlay notifications with position config (#110)

src/main/runtime/overlay-loading-osd.test.ts

@@ -0,0 +1,43 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import { createOverlayLoadingOsdController } from './overlay-loading-osd';
+
+test('overlay loading OSD shows spinner ticks and clears when stopped', () => {
+  const messages: string[] = [];
+  const clearedTimers: unknown[] = [];
+  let tick: (() => void) | null = null;
+  const controller = createOverlayLoadingOsdController({
+    showOsd: (message) => {
+      messages.push(message);
+    },
+    clearOsd: () => {
+      messages.push('clear');
+    },
+    setInterval: (callback) => {
+      tick = callback;
+      return 'timer';
+    },
+    clearInterval: (timer) => {
+      clearedTimers.push(timer);
+    },
+  });
+
+  controller.start();
+  controller.start();
+
+  assert.deepEqual(messages, ['Overlay loading |']);
+  if (!tick) {
+    assert.fail('expected spinner tick callback');
+  }
+  const tickCallback: () => void = tick;
+  tickCallback();
+  tickCallback();
+
+  controller.stop();
+  controller.stop();
+
+  assert.deepEqual(messages, ['Overlay loading |', 'Overlay loading /', 'Overlay loading -', 'clear']);
+  assert.deepEqual(clearedTimers, ['timer']);
+});
+