refactor: establish frontend request and state boundaries

tests/test_frontend_boundaries.py

@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+import re
+import unittest
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+STATIC = ROOT / "static"
+
+
+class FrontendBoundaryTests(unittest.TestCase):
+    def test_shared_api_is_the_only_application_fetch_exit(self) -> None:
+        fetch_files = []
+        for path in STATIC.rglob("*.js"):
+            if "vendor" in path.parts:
+                continue
+            if re.search(r"\bfetch\s*\(", path.read_text(encoding="utf-8")):
+                fetch_files.append(path.relative_to(STATIC).as_posix())
+        self.assertEqual(fetch_files, ["shared/api.js"])
+
+    def test_shared_dependencies_load_before_application(self) -> None:
+        html = (STATIC / "index.html").read_text(encoding="utf-8")
+        state_position = html.index('/shared/state.js')
+        api_position = html.index('/shared/api.js')
+        app_position = html.index('/app.js')
+        self.assertLess(state_position, api_position)
+        self.assertLess(api_position, app_position)
+
+    def test_application_state_is_created_through_shared_boundary(self) -> None:
+        app = (STATIC / "app.js").read_text(encoding="utf-8")
+        self.assertIn("const state = window.XiaobaiState.create({", app)
+        self.assertNotIn("const state = {", app)
+
+
+if __name__ == "__main__":
+    unittest.main()