tests/test_git_refs.py - git-repo - Git at Google

 # Copyright (C) 2026 The Android Open Source Project
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 #      http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.

 """Unittests for the git_refs.py module."""

 import os
 from pathlib import Path
 import subprocess
 from typing import Any, List
 from unittest import mock

 import pytest
 import utils_for_test

 import git_refs


 def _run(repo: str, *args: str) -> str:
     return subprocess.run(
         ["git", "-C", repo, *args],
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
         encoding="utf-8",
         check=True,
     ).stdout.strip()


 def _init_repo(tmp_path: Path, reftable: bool = False) -> str:
     repo = os.path.join(tmp_path, "repo")
     ref_format = "reftable" if reftable else "files"
     utils_for_test.init_git_tree(repo, ref_format=ref_format)

     Path(os.path.join(repo, "a")).write_text("1")
     _run(repo, "add", "a")
     _run(repo, "commit", "-q", "-m", "init")
     return repo


 @pytest.mark.parametrize("reftable", [False, True])
 def test_reads_refs(tmp_path, reftable):
     if reftable and not utils_for_test.supports_reftable():
         pytest.skip("reftable not supported")

     repo = _init_repo(tmp_path, reftable=reftable)
     gitdir = os.path.join(repo, ".git")
     refs = git_refs.GitRefs(gitdir)

     branch = _run(repo, "symbolic-ref", "--short", "HEAD")
     head = _run(repo, "rev-parse", "HEAD")
     assert refs.symref("HEAD") == f"refs/heads/{branch}"
     assert refs.head == f"refs/heads/{branch}"
     assert refs.get("HEAD") == head
     assert refs.get(f"refs/heads/{branch}") == head


 @pytest.mark.parametrize("reftable", [False, True])
 def test_reads_detached_head(tmp_path: Path, reftable: bool) -> None:
     if reftable and not utils_for_test.supports_reftable():
         pytest.skip("reftable not supported")

     repo = _init_repo(tmp_path, reftable=reftable)
     head = _run(repo, "rev-parse", "HEAD")
     _run(repo, "checkout", "--detach", head)
     refs = git_refs.GitRefs(os.path.join(repo, ".git"))

     assert refs.symref("HEAD") == ""
     assert refs.head == head
     assert refs.get("HEAD") == head


 def test_reads_head_with_root_refs_in_one_command(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     """Git 2.45 and newer include HEAD in the ref snapshot."""
     head = "1" * 40
     commands = []

     class FakeGitCommand:
         def __init__(
             self, _project: Any, cmdv: List[str], **_kwargs: Any
         ) -> None:
             commands.append(cmdv)
             self.stdout = (
                 f"{head}\0HEAD\0refs/heads/main\n"
                 f"{head}\0refs/heads/main\0\n"
             )

         def Wait(self) -> int:
             return 0

     monkeypatch.setattr(git_refs, "GitCommand", FakeGitCommand)
     monkeypatch.setattr(git_refs, "git_require", lambda _version: True)
     refs = git_refs.GitRefs("/nonexistent")
     with mock.patch.object(refs, "_ReadSymbolicRef") as read_head:
         assert refs.get("HEAD") == head

     assert commands == [
         [
             "for-each-ref",
             "--include-root-refs",
             "--format=%(objectname)%00%(refname)%00%(symref)",
             "HEAD",
             "refs",
         ]
     ]
     read_head.assert_not_called()


 def test_root_ref_snapshot_falls_back_for_unborn_head(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     """An unborn HEAD still uses symbolic-ref after the ref snapshot."""

     class FakeGitCommand:
         def __init__(
             self, _project: Any, _cmdv: List[str], **_kwargs: Any
         ) -> None:
             self.stdout = ""

         def Wait(self) -> int:
             return 0

     monkeypatch.setattr(git_refs, "GitCommand", FakeGitCommand)
     monkeypatch.setattr(git_refs, "git_require", lambda _version: True)
     refs = git_refs.GitRefs("/nonexistent")

     def read_head(name: str) -> None:
         assert name == "HEAD"
         refs._symref[name] = "refs/heads/main"

     monkeypatch.setattr(refs, "_ReadSymbolicRef", read_head)

     assert refs.symref("HEAD") == "refs/heads/main"


 def test_old_git_keeps_separate_head_fallback(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     """Git before 2.45 uses the original for-each-ref and HEAD calls."""
     head = "1" * 40
     commands = []

     class FakeGitCommand:
         def __init__(
             self, _project: Any, cmdv: List[str], **_kwargs: Any
         ) -> None:
             commands.append(cmdv)
             self.stdout = f"{head}\0refs/heads/main\0\n"

         def Wait(self) -> int:
             return 0

     monkeypatch.setattr(git_refs, "GitCommand", FakeGitCommand)
     monkeypatch.setattr(git_refs, "git_require", lambda _version: False)
     refs = git_refs.GitRefs("/nonexistent")

     def read_head(name: str) -> None:
         assert name == "HEAD"
         refs._symref[name] = "refs/heads/main"

     monkeypatch.setattr(refs, "_ReadSymbolicRef", read_head)

     assert refs.get("HEAD") == head
     assert commands == [
         [
             "for-each-ref",
             "--format=%(objectname)%00%(refname)%00%(symref)",
         ]
     ]


 def test_for_each_ref_failure_falls_back_to_symbolic_ref(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     """When for-each-ref fails, HEAD is still resolved via symbolic-ref."""

     class FakeGitCommand:
         def __init__(
             self, _project: Any, _cmdv: List[str], **_kwargs: Any
         ) -> None:
             self.stdout = ""

         def Wait(self) -> int:
             return 1

     monkeypatch.setattr(git_refs, "GitCommand", FakeGitCommand)
     monkeypatch.setattr(git_refs, "git_require", lambda _version: True)
     refs = git_refs.GitRefs("/nonexistent")

     def read_head(name: str) -> None:
         assert name == "HEAD"
         refs._symref[name] = "refs/heads/main"

     monkeypatch.setattr(refs, "_ReadSymbolicRef", read_head)

     assert refs.symref("HEAD") == "refs/heads/main"


 @pytest.mark.parametrize("reftable", [False, True])
 def test_updates_when_refs_change(tmp_path, reftable):
     if reftable and not utils_for_test.supports_reftable():
         pytest.skip("reftable not supported")

     repo = _init_repo(tmp_path, reftable=reftable)
     gitdir = os.path.join(repo, ".git")
     refs = git_refs.GitRefs(gitdir)

     head = _run(repo, "rev-parse", "HEAD")
     assert refs.get("refs/heads/topic") == ""
     _run(repo, "branch", "topic")
     assert refs.get("refs/heads/topic") == head
     _run(repo, "branch", "-D", "topic")
     assert refs.get("refs/heads/topic") == ""


 @pytest.mark.skipif(
     not utils_for_test.supports_refs_migrate(),
     reason="git refs migrate reftable support is required for this test",
 )
 def test_updates_when_storage_backend_toggles(tmp_path):
     repo = _init_repo(tmp_path, reftable=False)
     gitdir = os.path.join(repo, ".git")
     refs = git_refs.GitRefs(gitdir)

     head = _run(repo, "rev-parse", "HEAD")
     assert refs.get("refs/heads/reftable-branch") == ""
     _run(repo, "refs", "migrate", "--ref-format=reftable")
     _run(repo, "branch", "reftable-branch")
     assert refs.get("refs/heads/reftable-branch") == head

     assert refs.get("refs/heads/files-branch") == ""
     _run(repo, "refs", "migrate", "--ref-format=files")
     _run(repo, "branch", "files-branch")
     assert refs.get("refs/heads/files-branch") == head
	# Copyright (C) 2026 The Android Open Source Project
	#
	# Licensed under the Apache License, Version 2.0 (the "License");
	# you may not use this file except in compliance with the License.
	# You may obtain a copy of the License at
	#
	# http://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software
	# distributed under the License is distributed on an "AS IS" BASIS,
	# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	# See the License for the specific language governing permissions and
	# limitations under the License.

	"""Unittests for the git_refs.py module."""

	import os
	from pathlib import Path
	import subprocess
	from typing import Any, List
	from unittest import mock

	import pytest
	import utils_for_test

	import git_refs


	def _run(repo: str, *args: str) -> str:
	return subprocess.run(
	["git", "-C", repo, *args],
	stdout=subprocess.PIPE,
	stderr=subprocess.PIPE,
	encoding="utf-8",
	check=True,
	).stdout.strip()


	def _init_repo(tmp_path: Path, reftable: bool = False) -> str:
	repo = os.path.join(tmp_path, "repo")
	ref_format = "reftable" if reftable else "files"
	utils_for_test.init_git_tree(repo, ref_format=ref_format)

	Path(os.path.join(repo, "a")).write_text("1")
	_run(repo, "add", "a")
	_run(repo, "commit", "-q", "-m", "init")
	return repo


	@pytest.mark.parametrize("reftable", [False, True])
	def test_reads_refs(tmp_path, reftable):
	if reftable and not utils_for_test.supports_reftable():
	pytest.skip("reftable not supported")

	repo = _init_repo(tmp_path, reftable=reftable)
	gitdir = os.path.join(repo, ".git")
	refs = git_refs.GitRefs(gitdir)

	branch = _run(repo, "symbolic-ref", "--short", "HEAD")
	head = _run(repo, "rev-parse", "HEAD")
	assert refs.symref("HEAD") == f"refs/heads/{branch}"
	assert refs.head == f"refs/heads/{branch}"
	assert refs.get("HEAD") == head
	assert refs.get(f"refs/heads/{branch}") == head


	@pytest.mark.parametrize("reftable", [False, True])
	def test_reads_detached_head(tmp_path: Path, reftable: bool) -> None:
	if reftable and not utils_for_test.supports_reftable():
	pytest.skip("reftable not supported")

	repo = _init_repo(tmp_path, reftable=reftable)
	head = _run(repo, "rev-parse", "HEAD")
	_run(repo, "checkout", "--detach", head)
	refs = git_refs.GitRefs(os.path.join(repo, ".git"))

	assert refs.symref("HEAD") == ""
	assert refs.head == head
	assert refs.get("HEAD") == head


	def test_reads_head_with_root_refs_in_one_command(
	monkeypatch: pytest.MonkeyPatch,
	) -> None:
	"""Git 2.45 and newer include HEAD in the ref snapshot."""
	head = "1" * 40
	commands = []

	class FakeGitCommand:
	def __init__(
	self, _project: Any, cmdv: List[str], **_kwargs: Any
	) -> None:
	commands.append(cmdv)
	self.stdout = (
	f"{head}\0HEAD\0refs/heads/main\n"
	f"{head}\0refs/heads/main\0\n"
	)

	def Wait(self) -> int:
	return 0

	monkeypatch.setattr(git_refs, "GitCommand", FakeGitCommand)
	monkeypatch.setattr(git_refs, "git_require", lambda _version: True)
	refs = git_refs.GitRefs("/nonexistent")
	with mock.patch.object(refs, "_ReadSymbolicRef") as read_head:
	assert refs.get("HEAD") == head

	assert commands == [
	[
	"for-each-ref",
	"--include-root-refs",
	"--format=%(objectname)%00%(refname)%00%(symref)",
	"HEAD",
	"refs",
	]
	]
	read_head.assert_not_called()


	def test_root_ref_snapshot_falls_back_for_unborn_head(
	monkeypatch: pytest.MonkeyPatch,
	) -> None:
	"""An unborn HEAD still uses symbolic-ref after the ref snapshot."""

	class FakeGitCommand:
	def __init__(
	self, _project: Any, _cmdv: List[str], **_kwargs: Any
	) -> None:
	self.stdout = ""

	def Wait(self) -> int:
	return 0

	monkeypatch.setattr(git_refs, "GitCommand", FakeGitCommand)
	monkeypatch.setattr(git_refs, "git_require", lambda _version: True)
	refs = git_refs.GitRefs("/nonexistent")

	def read_head(name: str) -> None:
	assert name == "HEAD"
	refs._symref[name] = "refs/heads/main"

	monkeypatch.setattr(refs, "_ReadSymbolicRef", read_head)

	assert refs.symref("HEAD") == "refs/heads/main"


	def test_old_git_keeps_separate_head_fallback(
	monkeypatch: pytest.MonkeyPatch,
	) -> None:
	"""Git before 2.45 uses the original for-each-ref and HEAD calls."""
	head = "1" * 40
	commands = []

	class FakeGitCommand:
	def __init__(
	self, _project: Any, cmdv: List[str], **_kwargs: Any
	) -> None:
	commands.append(cmdv)
	self.stdout = f"{head}\0refs/heads/main\0\n"

	def Wait(self) -> int:
	return 0

	monkeypatch.setattr(git_refs, "GitCommand", FakeGitCommand)
	monkeypatch.setattr(git_refs, "git_require", lambda _version: False)
	refs = git_refs.GitRefs("/nonexistent")

	def read_head(name: str) -> None:
	assert name == "HEAD"
	refs._symref[name] = "refs/heads/main"

	monkeypatch.setattr(refs, "_ReadSymbolicRef", read_head)

	assert refs.get("HEAD") == head
	assert commands == [
	[
	"for-each-ref",
	"--format=%(objectname)%00%(refname)%00%(symref)",
	]
	]


	def test_for_each_ref_failure_falls_back_to_symbolic_ref(
	monkeypatch: pytest.MonkeyPatch,
	) -> None:
	"""When for-each-ref fails, HEAD is still resolved via symbolic-ref."""

	class FakeGitCommand:
	def __init__(
	self, _project: Any, _cmdv: List[str], **_kwargs: Any
	) -> None:
	self.stdout = ""

	def Wait(self) -> int:
	return 1

	monkeypatch.setattr(git_refs, "GitCommand", FakeGitCommand)
	monkeypatch.setattr(git_refs, "git_require", lambda _version: True)
	refs = git_refs.GitRefs("/nonexistent")

	def read_head(name: str) -> None:
	assert name == "HEAD"
	refs._symref[name] = "refs/heads/main"

	monkeypatch.setattr(refs, "_ReadSymbolicRef", read_head)

	assert refs.symref("HEAD") == "refs/heads/main"


	@pytest.mark.parametrize("reftable", [False, True])
	def test_updates_when_refs_change(tmp_path, reftable):
	if reftable and not utils_for_test.supports_reftable():
	pytest.skip("reftable not supported")

	repo = _init_repo(tmp_path, reftable=reftable)
	gitdir = os.path.join(repo, ".git")
	refs = git_refs.GitRefs(gitdir)

	head = _run(repo, "rev-parse", "HEAD")
	assert refs.get("refs/heads/topic") == ""
	_run(repo, "branch", "topic")
	assert refs.get("refs/heads/topic") == head
	_run(repo, "branch", "-D", "topic")
	assert refs.get("refs/heads/topic") == ""


	@pytest.mark.skipif(
	not utils_for_test.supports_refs_migrate(),
	reason="git refs migrate reftable support is required for this test",
	)
	def test_updates_when_storage_backend_toggles(tmp_path):
	repo = _init_repo(tmp_path, reftable=False)
	gitdir = os.path.join(repo, ".git")
	refs = git_refs.GitRefs(gitdir)

	head = _run(repo, "rev-parse", "HEAD")
	assert refs.get("refs/heads/reftable-branch") == ""
	_run(repo, "refs", "migrate", "--ref-format=reftable")
	_run(repo, "branch", "reftable-branch")
	assert refs.get("refs/heads/reftable-branch") == head

	assert refs.get("refs/heads/files-branch") == ""
	_run(repo, "refs", "migrate", "--ref-format=files")
	_run(repo, "branch", "files-branch")
	assert refs.get("refs/heads/files-branch") == head