Fix regression when using empty username/password

This change fixes a regression in the password manager that disallowed
the use of empty username or password as required by some self-hosted
repositories.

Relates-to: #9079 #2538

src/poetry/utils/password_manager.py

@@ -195,18 +195,25 @@ def delete_pypi_token(self, repo_name: str) -> None:
     def get_http_auth(self, repo_name: str) -> dict[str, str | None] | None:
         username = self._config.get(f"http-basic.{repo_name}.username")
         password = self._config.get(f"http-basic.{repo_name}.password")
-        if not username and not password:
+
+        # we only return None if both values are None or ""
+        # password can be None at this stage with the username ""
+        if (username is password is None) or (username == password == ""):
             return None
 
         if not password:
             if self.use_keyring:
                 password = self.keyring.get_password(repo_name, username)
-            else:
+            elif not username:
+                # at this tage if username is "" or None, auth is invalid
                 return None
 
+        if not username and not password:
+            return None
+
         return {
-            "username": username,
-            "password": password,
+            "username": username or "",
+            "password": password or "",
         }
 
     def set_http_password(self, repo_name: str, username: str, password: str) -> None:

tests/utils/test_password_manager.py

@@ -36,19 +36,36 @@ def test_set_http_password(
     assert "password" not in auth
 
 
+@pytest.mark.parametrize(
+    ("username", "password", "is_valid"),
+    [
+        ("bar", "baz", True),
+        ("", "baz", True),
+        ("bar", "", True),
+        ("", "", False),
+    ],
+)
 def test_get_http_auth(
-    config: Config, with_simple_keyring: None, dummy_keyring: DummyBackend
+    username: str,
+    password: str,
+    is_valid: bool,
+    config: Config,
+    with_simple_keyring: None,
+    dummy_keyring: DummyBackend,
 ) -> None:
-    dummy_keyring.set_password("poetry-repository-foo", "bar", "baz")
-    config.auth_config_source.add_property("http-basic.foo", {"username": "bar"})
+    dummy_keyring.set_password("poetry-repository-foo", username, password)
+    config.auth_config_source.add_property("http-basic.foo", {"username": username})
     manager = PasswordManager(config)
 
     assert PoetryKeyring.is_available()
     auth = manager.get_http_auth("foo")
-    assert auth is not None
 
-    assert auth["username"] == "bar"
-    assert auth["password"] == "baz"
+    if is_valid:
+        assert auth is not None
+        assert auth["username"] == username
+        assert auth["password"] == password
+    else:
+        assert auth is None
 
 
 def test_delete_http_password(
@@ -113,20 +130,36 @@ def test_set_http_password_with_unavailable_backend(
     assert auth["password"] == "baz"
 
 
+@pytest.mark.parametrize(
+    ("username", "password", "is_valid"),
+    [
+        ("bar", "baz", True),
+        ("", "baz", True),
+        ("bar", "", True),
+        ("", "", False),
+    ],
+)
 def test_get_http_auth_with_unavailable_backend(
-    config: Config, with_fail_keyring: None
+    username: str,
+    password: str,
+    is_valid: bool,
+    config: Config,
+    with_fail_keyring: None,
 ) -> None:
     config.auth_config_source.add_property(
-        "http-basic.foo", {"username": "bar", "password": "baz"}
+        "http-basic.foo", {"username": username, "password": password}
     )
     manager = PasswordManager(config)
 
     assert not PoetryKeyring.is_available()
     auth = manager.get_http_auth("foo")
-    assert auth is not None
 
-    assert auth["username"] == "bar"
-    assert auth["password"] == "baz"
+    if is_valid:
+        assert auth is not None
+        assert auth["username"] == username
+        assert auth["password"] == password
+    else:
+        assert auth is None
 
 
 def test_delete_http_password_with_unavailable_backend(