perf: precompress immutable dashboard runtime (#431)

tests/test_frontend_bundle.py

@@ -5,6 +5,7 @@ from pathlib import Path
 
 import httpx
 import pytest
+from starlette.requests import Request
 
 from src import main
 from src.frontend_bundle import build_frontend
@@ -21,6 +22,8 @@ def test_page_runtime_is_one_deterministic_content_addressed_bundle(tmp_path):
 
     assert first.runtime_name == second.runtime_name
     assert first.runtime_bytes == second.runtime_bytes
+    assert first.runtime_gzip_bytes == second.runtime_gzip_bytes
+    assert gzip.decompress(first.runtime_gzip_bytes) == first.runtime_bytes
     assert PAGE_SCRIPT.findall(first.dashboard_html) == []
     assert first.dashboard_html.count("<script src=") == 1
     assert f'<script src="{first.runtime_name}"></script>' in first.dashboard_html
@@ -52,11 +55,46 @@ async def test_runtime_is_transferred_as_gzip_when_the_client_accepts_it():
     assert response.status_code == 200
     assert response.headers["content-encoding"] == "gzip"
     assert response.headers["vary"] == "Accept-Encoding"
-    assert int(response.headers["content-length"]) <= 100 * 1024
+    assert int(response.headers["content-length"]) == len(main.FRONTEND_BUILD.runtime_gzip_bytes)
     assert response.content == main.FRONTEND_BUILD.runtime_bytes
     assert response.headers["cache-control"] == "public, max-age=31536000, immutable"
 
 
+@pytest.mark.anyio
+async def test_runtime_route_returns_the_precomputed_gzip_representation():
+    build = build_frontend(FRONTEND)
+    request = Request(
+        {"type": "http", "method": "GET", "path": f"/{build.runtime_name}",
+         "headers": [(b"accept-encoding", b"gzip")]}
+    )
+
+    response = await runtime_bundle(build.runtime_digest, request)
+
+    assert response.body == build.runtime_gzip_bytes
+    assert response.headers["content-encoding"] == "gzip"
+    assert response.headers["content-length"] == str(len(build.runtime_gzip_bytes))
+    assert response.headers["vary"] == "Accept-Encoding"
+
+
+@pytest.mark.anyio
+async def test_runtime_requests_bypass_dynamic_gzip_compression(monkeypatch):
+    class UnexpectedDynamicCompression:
+        def __init__(self, *args, **kwargs):
+            raise AssertionError("immutable runtime entered dynamic compression")
+
+    monkeypatch.setattr("src.compression.GZipResponder", UnexpectedDynamicCompression)
+    transport = httpx.ASGITransport(app=main.app)
+
+    async with httpx.AsyncClient(transport=transport, base_url="http://test") as client:
+        response = await client.get(
+            f"/{main.FRONTEND_BUILD.runtime_name}",
+            headers={"Accept-Encoding": "gzip"},
+        )
+
+    assert response.status_code == 200
+    assert response.headers["content-encoding"] == "gzip"
+
+
 @pytest.mark.anyio
 @pytest.mark.parametrize("accept_encoding", ["identity", "gzip;q=0, identity;q=1"])
 async def test_runtime_stays_unencoded_when_the_client_declines_gzip(accept_encoding):
@@ -108,9 +146,13 @@ def test_offline_shell_precaches_exact_runtime_without_superseded_page_modules()
 @pytest.mark.anyio
 async def test_runtime_asset_is_immutable_while_html_and_worker_revalidate():
     build = build_frontend(FRONTEND)
+    request = Request(
+        {"type": "http", "method": "GET", "path": f"/{build.runtime_name}",
+         "headers": [(b"accept-encoding", b"identity")]}
+    )
 
     html = await dashboard()
-    bundle = await runtime_bundle(build.runtime_digest)
+    bundle = await runtime_bundle(build.runtime_digest, request)
     worker = await service_worker()
 
     assert build.runtime_name in html