Make the call to actual download a bit less nested

src/pip/_internal/network/download.py

@@ -24,7 +24,7 @@
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 if MYPY_CHECK_RUNNING:
-    from typing import Iterable, Optional
+    from typing import Iterable, Optional, Tuple
 
     from pip._vendor.requests.models import Response
 
@@ -133,27 +133,6 @@ def _get_http_response_filename(resp, link):
     return filename
 
 
-def _http_get_download(session, link):
-    # type: (PipSession, Link) -> Response
-    target_url = link.url.split('#', 1)[0]
-    resp = session.get(target_url, headers=HEADERS, stream=True)
-    raise_for_status(resp)
-    return resp
-
-
-class Download(object):
-    def __init__(
-        self,
-        response,  # type: Response
-        filename,  # type: str
-        chunks,  # type: Iterable[bytes]
-    ):
-        # type: (...) -> None
-        self.response = response
-        self.filename = filename
-        self.chunks = chunks
-
-
 class Downloader(object):
     def __init__(
         self,
@@ -164,19 +143,24 @@ def __init__(
         self._session = session
         self._progress_bar = progress_bar
 
-    def __call__(self, link):
-        # type: (Link) -> Download
+    def __call__(self, link, tmpdir):
+        # type: (Link, str) -> Tuple[str, str]
+        url = link.url.split('#', 1)[0]
+        response = self._session.get(url, headers=HEADERS, stream=True)
         try:
-            resp = _http_get_download(self._session, link)
+            raise_for_status(response)
         except NetworkConnectionError as e:
             assert e.response is not None
             logger.critical(
                 "HTTP error %s while getting %s", e.response.status_code, link
             )
             raise
 
-        return Download(
-            resp,
-            _get_http_response_filename(resp, link),
-            _prepare_download(resp, link, self._progress_bar),
-        )
+        chunks = _prepare_download(response, link, self._progress_bar)
+        filename = _get_http_response_filename(response, link)
+        file_path = os.path.join(tmpdir, filename)
+
+        with open(file_path, 'wb') as content_file:
+            for chunk in chunks:
+                content_file.write(chunk)
+        return file_path, response.headers.get('content-type', '')

src/pip/_internal/operations/prepare.py

@@ -39,9 +39,7 @@
 from pip._internal.vcs import vcs
 
 if MYPY_CHECK_RUNNING:
-    from typing import (
-        Callable, List, Optional, Tuple,
-    )
+    from typing import Callable, List, Optional
 
     from mypy_extensions import TypedDict
 
@@ -126,9 +124,9 @@ def get_http_url(
         content_type = mimetypes.guess_type(from_path)[0]
     else:
         # let's download to a tmp dir
-        from_path, content_type = _download_http_url(
-            link, downloader, temp_dir.path, hashes
-        )
+        from_path, content_type = downloader(link, temp_dir.path)
+        if hashes:
+            hashes.check_against_path(from_path)
 
     return File(from_path, content_type)
 
@@ -267,27 +265,6 @@ def unpack_url(
     return file
 
 
-def _download_http_url(
-    link,  # type: Link
-    downloader,  # type: Downloader
-    temp_dir,  # type: str
-    hashes,  # type: Optional[Hashes]
-):
-    # type: (...) -> Tuple[str, str]
-    """Download link url into temp_dir using provided session"""
-    download = downloader(link)
-
-    file_path = os.path.join(temp_dir, download.filename)
-    with open(file_path, 'wb') as content_file:
-        for chunk in download.chunks:
-            content_file.write(chunk)
-
-    if hashes:
-        hashes.check_against_path(file_path)
-
-    return file_path, download.response.headers.get('content-type', '')
-
-
 def _check_download_dir(link, download_dir, hashes):
     # type: (Link, str, Optional[Hashes]) -> Optional[str]
     """ Check download_dir for previously downloaded file with correct hash

tests/unit/test_operations_prepare.py

@@ -10,11 +10,7 @@
 from pip._internal.models.link import Link
 from pip._internal.network.download import Downloader
 from pip._internal.network.session import PipSession
-from pip._internal.operations.prepare import (
-    _copy_source_tree,
-    _download_http_url,
-    unpack_url,
-)
+from pip._internal.operations.prepare import _copy_source_tree, unpack_url
 from pip._internal.utils.hashes import Hashes
 from pip._internal.utils.urls import path_to_url
 from tests.lib.filesystem import (
@@ -83,12 +79,7 @@ def test_download_http_url__no_directory_traversal(mock_raise_for_status,
 
     download_dir = tmpdir.joinpath('download')
     os.mkdir(download_dir)
-    file_path, content_type = _download_http_url(
-        link,
-        downloader,
-        download_dir,
-        hashes=None,
-    )
+    file_path, content_type = downloader(link, download_dir)
     # The file should be downloaded to download_dir.
     actual = os.listdir(download_dir)
     assert actual == ['out_dir_file']