Add git info and Python package info providers

They are classes with minimal state and a no-arguments `__call__()`
operator, giving a dictionary of context values as required.

Tests both providers in a lean unit test each.

pyproject.toml

@@ -107,7 +107,7 @@ ignore = [
 
 [tool.bandit]
 exclude_dirs = ["examples", "tests"]
-skips = ["B101"]
+skips = ["B101", "B404"]
 
 [tool.pytest.ini_options]
 log_cli = true

src/nnbench/context.py

@@ -17,3 +17,100 @@ def cpuarch() -> dict[str, str]:
 
 def python_version() -> dict[str, str]:
     return {"python_version": platform.python_version()}
+
+
+class PythonPackageInfo:
+    """
+    A context helper returning version info for requested installed packages.
+
+    If a requested package is not installed, an empty string is returned instead.
+
+    Parameters
+    ----------
+    *packages: str
+        Names of the requested packages under which they exist in the current environment.
+        For packages installed through ``pip``, this equals the PyPI package name.
+    """
+
+    def __init__(self, *packages: str):
+        self.packages = packages
+
+    def __call__(self) -> dict[str, str]:
+        from importlib.metadata import PackageNotFoundError, version
+
+        result: dict[str, str] = {}
+        for pkg in self.packages:
+            try:
+                result[pkg] = version(pkg)
+            except PackageNotFoundError:
+                result[pkg] = ""
+        return result
+
+
+class GitEnvironmentInfo:
+    """
+    A context helper providing the current git commit, latest tag, and upstream repository name.
+
+    Parameters
+    ----------
+    remote: str
+        Remote name for which to provide info, by default ``"origin"``.
+    """
+
+    def __init__(self, remote: str = "origin"):
+        self.remote = remote
+
+    def __call__(self) -> dict[str, str]:
+        import subprocess
+
+        def git_subprocess(args: list[str]) -> subprocess.CompletedProcess:
+            if platform.system() == "Windows":
+                git = "git.exe"
+            else:
+                git = "git"
+
+            return subprocess.run(  # nosec: B603
+                [git, *args], stdout=subprocess.PIPE, stderr=subprocess.PIPE, encoding="utf-8"
+            )
+
+        result: dict[str, str] = {
+            "commit": "",
+            "provider": "",
+            "repository": "",
+            "tag": "",
+        }
+
+        # first, check if inside a repo.
+        rc = subprocess.call(["git", "rev-parse", "--is-inside-work-tree"])  # nosec: B603, B607
+        # if not, return empty info.
+        if rc:
+            return result
+
+        # secondly: get the current commit.
+        p = git_subprocess(["rev-parse", "HEAD"])
+        if not p.returncode:
+            result["commit"] = p.stdout.strip()
+
+        # thirdly, get the latest tag, without a short commit SHA attached.
+        p = git_subprocess(["describe", "--tags", "--abbrev=0"])
+        if not p.returncode:
+            result["tag"] = p.stdout.strip()
+
+        # and finally, get the remote repo name pointed to by the given remote.
+        p = git_subprocess(["remote", "get-url", self.remote])
+        if not p.returncode:
+            remotename: str = p.stdout.strip()
+            # it's an SSH remote.
+            if "@" in remotename:
+                prefix, sep = "git@", ":"
+            else:
+                # it is HTTPS.
+                prefix, sep = "https://", "/"
+
+            remotename = remotename.removeprefix(prefix)
+            provider, reponame = remotename.split(sep, 1)
+
+            result["provider"] = provider
+            result["repository"] = reponame.removesuffix(".git")
+
+        return result

tests/test_context.py

@@ -0,0 +1,24 @@
+from nnbench.context import GitEnvironmentInfo, PythonPackageInfo
+
+
+def test_python_package_info() -> None:
+    p = PythonPackageInfo("pre-commit", "pyyaml")()
+
+    for v in p.values():
+        assert v != ""
+
+    # for a bogus package, it should not fail but produce an empty string.
+    p = PythonPackageInfo("asdfghjkl")()
+
+    for v in p.values():
+        assert v == ""
+
+
+def test_git_info_provider() -> None:
+    g = GitEnvironmentInfo()()
+
+    # tag might not be available in a shallow checkout in CI,
+    # but commit, provider and repo are.
+    assert g["commit"] != ""
+    assert g["provider"] == "github.com"
+    assert g["repository"] == "aai-institute/nnbench"