Add script to download wheels from appveyor

maint/scripts/download_wheels.py

@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+
+import asyncio
+import json
+import pathlib
+import sys
+from tornado.httpclient import AsyncHTTPClient
+
+BASE_URL = "https://ci.appveyor.com/api"
+
+
+async def fetch_job(directory, job):
+    http = AsyncHTTPClient()
+    artifacts = await http.fetch(f"{BASE_URL}/buildjobs/{job}/artifacts")
+    paths = [pathlib.PurePosixPath(a["fileName"]) for a in json.loads(artifacts.body)]
+
+    for path in paths:
+        artifact = await http.fetch(f"{BASE_URL}/buildjobs/{job}/artifacts/{path}")
+        with open(directory.joinpath(path.name), "wb") as f:
+            f.write(artifact.body)
+
+
+async def main():
+    http = AsyncHTTPClient()
+    try:
+        _, version = sys.argv
+    except ValueError:
+        print("usage: maint/scripts/download_wheels.py v6.0.1", file=sys.stderr)
+        sys.exit(1)
+
+    directory = pathlib.Path(f"downloads-{version}")
+    directory.mkdir(exist_ok=True)
+
+    build = await http.fetch(f"{BASE_URL}/projects/bdarnell/tornado/branch/{version}")
+    jobs = [job["jobId"] for job in json.loads(build.body)["build"]["jobs"]]
+
+    await asyncio.gather(*(fetch_job(directory, job) for job in jobs))
+
+
+if __name__ == "__main__":
+    asyncio.run(main())