chore: import upstream snapshot with attribution

tests/self_upgrade_helpers.py

@@ -0,0 +1,64 @@
+"""Shared fixtures and helpers for `specify self upgrade` tests.
+
+These helpers patch subprocess, PATH lookup, and release-tag resolution so
+the focused test modules stay isolated from the real environment.
+"""
+
+import os
+import subprocess
+
+import pytest
+from typer.testing import CliRunner
+
+from specify_cli._version import (
+    _InstallMethod,
+    _UpgradePlan,
+    _assemble_installer_argv,
+    _detect_install_method,
+    _verify_upgrade,
+)
+from tests.conftest import strip_ansi
+from tests.http_helpers import mock_urlopen_response
+
+__all__ = (
+    "SENTINEL_GH_TOKEN",
+    "SENTINEL_GITHUB_TOKEN",
+    "_InstallMethod",
+    "_UpgradePlan",
+    "_assemble_installer_argv",
+    "_completed_process",
+    "_detect_install_method",
+    "_verify_upgrade",
+    "mock_urlopen_response",
+    "requires_posix",
+    "runner",
+    "strip_ansi",
+)
+
+runner = CliRunner()
+
+# Some installer error-path tests create a relative `./uv` fixture, `chdir`
+# into the tmp dir, and assert POSIX executable-bit semantics (chmod / X_OK).
+# None of that maps cleanly onto Windows: `os.access(path, X_OK)` ignores the
+# mode bits, and pytest cannot rmtree a tmp dir that is still the cwd, so the
+# fixtures raise PermissionError during teardown. Skip these on Windows — the
+# realistic absolute-path and bare-PATH-command branches stay covered there.
+requires_posix = pytest.mark.skipif(
+    os.name == "nt",
+    reason="relative-path / executable-bit semantics are POSIX-only",
+)
+
+SENTINEL_GH_TOKEN = "SENTINEL-GH-TOKEN-VALUE"
+SENTINEL_GITHUB_TOKEN = "SENTINEL-GITHUB-TOKEN-VALUE"
+
+
+def _completed_process(
+    returncode: int, stdout: str = "", stderr: str = ""
+) -> subprocess.CompletedProcess:
+    """Build a subprocess.CompletedProcess for installer / verification calls."""
+    return subprocess.CompletedProcess(
+        args=["mocked"],
+        returncode=returncode,
+        stdout=stdout,
+        stderr=stderr,
+    )