fix: close final viewer integration gaps (#5)

tests/viewer2d.contract.test.ts

@@ -1,28 +1,26 @@
 import { readFile } from 'node:fs/promises';
-import { describe, expect, it } from 'vitest';
-import { isCad2DFile, parseCad } from '@hmwebviewer/viewer2d';
+import { describe, expect, it, vi } from 'vitest';
+import { isCad2DFile, loadCad } from '@hmwebviewer/viewer2d';
 
 describe('viewer2d package interface', () => {
-  it('parses the sample DXF through the public package interface', async () => {
+  it('parses and loads the sample DXF without exposing the parser result', async () => {
     const file = await readFile(
       new URL('../apps/viewer-2d-sample/public/samples/simple.dxf', import.meta.url),
     );
-    const result = await parseCad({
+    const viewer = {
+      load: vi.fn(),
+      resize: vi.fn(),
+    };
+    const summary = await loadCad(viewer, {
       name: 'simple.dxf',
       data: file.buffer.slice(file.byteOffset, file.byteOffset + file.byteLength),
     });
-    const entities = result.entities as Array<{ layer?: string; type?: string }>;
 
     expect(isCad2DFile('drawing.DWG')).toBe(true);
     expect(isCad2DFile('drawing.dxf')).toBe(true);
     expect(isCad2DFile('drawing.pdf')).toBe(false);
-    expect(entities.map(({ type, layer }) => [type, layer])).toEqual([
-      ['LINE', 'OUTLINE'],
-      ['LINE', 'OUTLINE'],
-      ['LINE', 'OUTLINE'],
-      ['LINE', 'OUTLINE'],
-      ['CIRCLE', '0'],
-      ['TEXT', '0'],
-    ]);
+    expect(summary).toEqual({ entityCount: 6 });
+    expect(viewer.load).toHaveBeenCalledOnce();
+    expect(viewer.resize).toHaveBeenCalledOnce();
   });
 });