make all generated servers pick an arbitrary free port

ideally, this should avoid collisions. no clue if this matters at all

tests/conftest.py

@@ -1115,7 +1115,8 @@ def html_index_with_onetime_server(
     """Serve files from a generated pypi index, erroring if a file is downloaded more
     than once.
 
-    Provide `-i http://localhost:8000` to pip invocations to point them at this server.
+    Provide `-i http://localhost:<port>` to pip invocations to point them at
+    this server.
     """
 
     class InDirectoryServer(http.server.ThreadingHTTPServer):
@@ -1130,7 +1131,7 @@ def finish_request(self: "Self", request: Any, client_address: Any) -> None:
     class Handler(OneTimeDownloadHandler):
         _seen_paths: ClassVar[Set[str]] = set()
 
-    with InDirectoryServer(("", 8000), Handler) as httpd:
+    with InDirectoryServer(("", 0), Handler) as httpd:
         server_thread = threading.Thread(target=httpd.serve_forever)
         server_thread.start()
 
@@ -1326,14 +1327,13 @@ def html_index_no_metadata(
 
 HTMLIndexWithRangeServer = Callable[
     [RangeHandler],
-    "AbstractContextManager[Type[ContentRangeDownloadHandler]]",
+    "AbstractContextManager[Tuple[Type[ContentRangeDownloadHandler], int]]",
 ]
 
 
 @pytest.fixture
 def html_index_with_range_server(
     html_index_no_metadata: Path,
-    port: int = 8000,
 ) -> HTMLIndexWithRangeServer:
     """Serve files from a generated pypi index, with support for range requests.
 
@@ -1350,7 +1350,7 @@ def finish_request(self, request: Any, client_address: Any) -> None:
     @contextmanager
     def inner(
         range_handler: RangeHandler,
-    ) -> Iterator[Type[ContentRangeDownloadHandler]]:
+    ) -> Iterator[Tuple[Type[ContentRangeDownloadHandler], int]]:
         class Handler(ContentRangeDownloadHandler):
             @property
             def range_handler(self) -> RangeHandler:
@@ -1362,18 +1362,15 @@ def range_handler(self) -> RangeHandler:
             head_request_paths: ClassVar[Set[str]] = set()
             ok_response_counts: ClassVar[Dict[str, int]] = {}
 
-        with InDirectoryServer(("", port), Handler) as httpd:
+        with InDirectoryServer(("", 0), Handler) as httpd:
             server_thread = threading.Thread(target=httpd.serve_forever)
             server_thread.start()
 
+            _, server_port = httpd.server_address
             try:
-                yield Handler
+                yield (Handler, server_port)
             finally:
                 httpd.shutdown()
-                server_thread.join(timeout=3.0)
-                if server_thread.is_alive():
-                    raise RuntimeError(
-                        "failed to shutdown http server within 3 seconds"
-                    )
+                server_thread.join()
 
     return inner

tests/functional/test_download.py

@@ -1273,6 +1273,7 @@ def download_server_html_index(
 ) -> Callable[..., Tuple[TestPipResult, Path]]:
     """Execute `pip download` against a generated PyPI index."""
     download_dir = tmpdir / "download_dir"
+    _, server_port = html_index_with_onetime_server.server_address
 
     def run_for_generated_index(
         args: List[str],
@@ -1287,7 +1288,7 @@ def run_for_generated_index(
             "-d",
             str(download_dir),
             "-i",
-            "http://localhost:8000",
+            f"http://localhost:{server_port}",
             *args,
         ]
         result = script.pip(*pip_args, allow_error=allow_error)

tests/functional/test_fast_deps.py

@@ -176,7 +176,7 @@ def test_download_range(
     """Execute `pip download` against a generated PyPI index."""
     download_dir = tmpdir / "download_dir"
 
-    def run_for_generated_index(args: List[str]) -> TestPipResult:
+    def run_for_generated_index(server_port: int, args: List[str]) -> TestPipResult:
         """
         Produce a PyPI directory structure pointing to the specified packages, then
         execute `pip download -i ...` pointing to our generated index.
@@ -187,14 +187,15 @@ def run_for_generated_index(args: List[str]) -> TestPipResult:
             "-d",
             str(download_dir),
             "-i",
-            "http://localhost:8000",
+            f"http://localhost:{server_port}",
             *args,
         ]
         return script.pip(*pip_args, allow_stderr_warning=True)
 
-    with html_index_with_range_server(range_handler) as handler:
+    with html_index_with_range_server(range_handler) as (handler, server_port):
         run_for_generated_index(
-            ["colander", "compilewheel==2.0", "has-script", "translationstring==0.1"]
+            server_port,
+            ["colander", "compilewheel==2.0", "has-script", "translationstring==0.1"],
         )
         generated_files = os.listdir(download_dir)
         assert fnmatch.filter(generated_files, "colander*.whl")