testlib.repo: Cache repository helper functions

The repository related helper functions are relatively costly,
given that they are run repeatedly from many different tests.
As the output of those functions is more or less static during a
test run, this change adds caching so we do not have to execute
the external commands multiple times.

CMK-20561

Change-Id: I6a2070ea8de4a2120e5bcfb404cdfd14b049cc61
(cherry picked from commit 0da7e2d)

tests/testlib/repo.py

@@ -10,12 +10,14 @@
 import subprocess
 import sys
 from contextlib import suppress
+from functools import cache
 from pathlib import Path
 from typing import Callable, Iterator
 
 logger = logging.getLogger(__name__)
 
 
+@cache
 def repo_path() -> Path:
     """Returns the checkout/worktree path (in contrast to the 'git-dir')
     same as result of `git rev-parse --show-toplevel`, but repo_path is being executed
@@ -48,10 +50,12 @@ def add_python_paths() -> None:
     sys.path.insert(0, os.path.join(repo_path(), "omd/packages/omd"))
 
 
+@cache
 def qa_test_data_path() -> Path:
     return Path(__file__).parent.parent.resolve() / Path("qa-test-data")
 
 
+@cache
 def branch_from_env(*, env_var: str, fallback: str | Callable[[], str] | None = None) -> str:
     if branch := os.environ.get(env_var):
         return branch
@@ -60,6 +64,7 @@ def branch_from_env(*, env_var: str, fallback: str | Callable[[], str] | None =
     raise RuntimeError(f"{env_var} environment variable, e.g. master, is missing")
 
 
+@cache
 def current_branch_version() -> str:
     return subprocess.check_output(
         [
@@ -73,6 +78,7 @@ def current_branch_version() -> str:
     ).strip()
 
 
+@cache
 def current_base_branch_name() -> str:
     branch_name = current_branch_name()
 
@@ -118,13 +124,15 @@ def current_base_branch_name() -> str:
     return branch_name
 
 
+@cache
 def current_branch_name() -> str:
     branch_name = subprocess.check_output(
         ["git", "rev-parse", "--abbrev-ref", "HEAD"], encoding="utf-8"
     )
     return branch_name.split("\n", 1)[0]
 
 
+@cache
 def git_commit_id(path: Path | str) -> str:
     """Returns the git hash for given @path."""
     return subprocess.check_output(
@@ -136,6 +144,7 @@ def git_commit_id(path: Path | str) -> str:
     ).strip("\n")
 
 
+@cache
 def git_essential_directories(checkout_dir: Path) -> Iterator[str]:
     """Yields paths to all directories needed to be accessible in order to run git operations
     Note that if a directory is a subdirectory of checkout_dir it will be skipped"""
@@ -165,6 +174,7 @@ def git_essential_directories(checkout_dir: Path) -> Iterator[str]:
                     yield alternate.as_posix()
 
 
+@cache
 def find_git_rm_mv_files(dirpath: Path) -> list[str]:
     del_files = []