Move Downloader construction out of RequirementPreparer

src/pip/_internal/cli/req_command.py

@@ -18,6 +18,7 @@
 from pip._internal.index.package_finder import PackageFinder
 from pip._internal.legacy_resolve import Resolver
 from pip._internal.models.selection_prefs import SelectionPreferences
+from pip._internal.network.download import Downloader
 from pip._internal.network.session import PipSession
 from pip._internal.operations.prepare import RequirementPreparer
 from pip._internal.req.constructors import (
@@ -162,17 +163,19 @@ def make_requirement_preparer(
         """
         Create a RequirementPreparer instance for the given parameters.
         """
+        downloader = Downloader(session, progress_bar=options.progress_bar)
+
         temp_build_dir_path = temp_build_dir.path
         assert temp_build_dir_path is not None
+
         return RequirementPreparer(
             build_dir=temp_build_dir_path,
             src_dir=options.src_dir,
             download_dir=download_dir,
             wheel_download_dir=wheel_download_dir,
-            progress_bar=options.progress_bar,
             build_isolation=options.build_isolation,
             req_tracker=req_tracker,
-            session=session,
+            downloader=downloader,
             finder=finder,
             require_hashes=options.require_hashes,
             use_user_site=use_user_site,

src/pip/_internal/operations/prepare.py

@@ -26,7 +26,6 @@
     PreviousBuildDirError,
     VcsHashUnsupported,
 )
-from pip._internal.network.download import Downloader
 from pip._internal.utils.compat import expanduser
 from pip._internal.utils.filesystem import copy2_fixed
 from pip._internal.utils.hashes import MissingHashes
@@ -56,7 +55,7 @@
     from pip._internal.distributions import AbstractDistribution
     from pip._internal.index.package_finder import PackageFinder
     from pip._internal.models.link import Link
-    from pip._internal.network.session import PipSession
+    from pip._internal.network.download import Downloader
     from pip._internal.req.req_install import InstallRequirement
     from pip._internal.req.req_tracker import RequirementTracker
     from pip._internal.utils.hashes import Hashes
@@ -359,10 +358,9 @@ def __init__(
         download_dir,  # type: Optional[str]
         src_dir,  # type: str
         wheel_download_dir,  # type: Optional[str]
-        progress_bar,  # type: str
         build_isolation,  # type: bool
         req_tracker,  # type: RequirementTracker
-        session,  # type: PipSession
+        downloader,  # type: Downloader
         finder,  # type: PackageFinder
         require_hashes,  # type: bool
         use_user_site,  # type: bool
@@ -373,7 +371,7 @@ def __init__(
         self.src_dir = src_dir
         self.build_dir = build_dir
         self.req_tracker = req_tracker
-        self.downloader = Downloader(session, progress_bar)
+        self.downloader = downloader
         self.finder = finder
 
         # Where still-packed archives should be written to. If None, they are

tests/unit/test_operations_prepare.py

@@ -9,9 +9,9 @@
 
 from pip._internal.exceptions import HashMismatch
 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 (
-    Downloader,
     _copy_source_tree,
     _download_http_url,
     unpack_file_url,

tests/unit/test_req.py

@@ -19,6 +19,7 @@
     PreviousBuildDirError,
 )
 from pip._internal.legacy_resolve import Resolver
+from pip._internal.network.download import Downloader
 from pip._internal.network.session import PipSession
 from pip._internal.operations.prepare import RequirementPreparer
 from pip._internal.req import InstallRequirement, RequirementSet
@@ -77,10 +78,9 @@ def _basic_resolver(self, finder, require_hashes=False):
                 src_dir=os.path.join(self.tempdir, 'src'),
                 download_dir=None,
                 wheel_download_dir=None,
-                progress_bar="on",
                 build_isolation=True,
                 req_tracker=tracker,
-                session=PipSession(),
+                downloader=Downloader(PipSession(), progress_bar="on"),
                 finder=finder,
                 require_hashes=require_hashes,
                 use_user_site=False,