feat: implement scale-of-fifth based key signature picker

src/components/common/FloatingPopup.test.tsx

@@ -0,0 +1,29 @@
+import React from 'react';
+import { fireEvent, render, screen } from '@testing-library/react';
+import { describe, expect, it, vi } from 'vitest';
+import FloatingPopup from './FloatingPopup';
+
+describe('FloatingPopup', () => {
+  it('closes on outside click and escape', () => {
+    const onClose = vi.fn();
+    render(
+      <div>
+        <FloatingPopup
+          isOpen={true}
+          onClose={onClose}
+          trigger={<button type="button">Toggle</button>}
+        >
+          <div>Popup body</div>
+        </FloatingPopup>
+        <button type="button">Outside</button>
+      </div>
+    );
+
+    expect(screen.getByRole('dialog')).toBeInTheDocument();
+
+    fireEvent.mouseDown(screen.getByRole('button', { name: 'Outside' }));
+    fireEvent.keyDown(document, { key: 'Escape' });
+
+    expect(onClose).toHaveBeenCalledTimes(2);
+  });
+});