Fix compat.get_session

- Fixes #56

Signed-off-by: Dan Ryan <dan.ryan@canonical.com>

.pre-commit-config.yaml

@@ -5,12 +5,12 @@ repos:
       - id: black
 
   - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v2.4.0
+    rev: v2.5.0
     hooks:
       - id: flake8
 
   - repo: https://github.com/asottile/seed-isort-config
-    rev: v1.9.4
+    rev: v2.1.0
     hooks:
       - id: seed-isort-config
 

news/56.bugfix.rst

@@ -0,0 +1 @@
+Fixed incorrect session creation via ``pip_shims.compat.get_session`` which inadvertently passed a tuple to pip when building a session instance.

src/pip_shims/compat.py

@@ -412,7 +412,7 @@ def get_session(
         assert isinstance(install_cmd_provider, (type, functools.partial))
         install_cmd = install_cmd_provider()
     if options is None:
-        options = install_cmd.parser.parse_args([])  # type: ignore
+        options, _ = install_cmd.parser.parse_args([])  # type: ignore
     session = install_cmd._build_session(options)  # type: ignore
     assert session is not None
     atexit.register(session.close)

tests/test_instances.py

@@ -72,6 +72,7 @@
     shim_unpack,
     url_to_path,
 )
+from pip_shims.compat import get_session
 
 STRING_TYPES = (str,)
 if sys.version_info < (3, 0):
@@ -612,3 +613,9 @@ def test_stdlib_pkgs():
     from pip_shims.shims import stdlib_pkgs
 
     assert "argparse" in stdlib_pkgs
+
+
+def test_get_session():
+    cmd = InstallCommand()
+    sess = get_session(install_cmd=cmd)
+    assert type(sess).__base__.__qualname__ == "Session"