feat(pygit2): signature doen't break if env is set and git conf not

src/scmrepo/git/backend/pygit2/__init__.py

@@ -142,14 +142,32 @@ def committer(self) -> "Signature":
     def _get_signature(self, name: str) -> "Signature":
         from pygit2 import Signature
 
-        sig = self.default_signature
+        try:
+            sig = self.default_signature
+        except SCMError:
+            logger.debug("No default signature (config is not set in repo)")
+            sig = None
+
         if os.environ.get(f"{name}_DATE"):
             raise NotImplementedError("signature date override unsupported")
+
+        user_name = os.environ.get(f"{name}_NAME", sig.name if sig else None)
+        user_email = os.environ.get(f"{name}_EMAIL", sig.email if sig else None)
+
+        if not user_email or not user_name:
+            raise SCMError("Git user name and email must be configured")
+
+        if sig:
+            return Signature(
+                name=user_name,
+                email=user_email,
+                time=sig.time,
+                offset=sig.offset,
+            )
+
         return Signature(
-            name=os.environ.get(f"{name}_NAME", sig.name),
-            email=os.environ.get(f"{name}_EMAIL", sig.email),
-            time=sig.time,
-            offset=sig.offset,
+            name=user_name,
+            email=user_email,
         )
 
     @staticmethod

tests/test_pygit2.py

@@ -1,9 +1,12 @@
 # pylint: disable=unused-argument
+import os
+
 import pygit2
 import pytest
 from pytest_mock import MockerFixture
 from pytest_test_utils import TmpDir
 
+from scmrepo.exceptions import SCMError
 from scmrepo.git import Git
 from scmrepo.git.backend.pygit2 import Pygit2Backend
 
@@ -68,8 +71,41 @@ def test_pygit_stash_apply_conflicts(
         "ssh://login@server.com:12345/repository.git",
     ],
 )
-def test_pygit2_ssh_error(tmp_dir: TmpDir, scm: Git, url):
+def test_pygit_ssh_error(tmp_dir: TmpDir, scm: Git, url):
     backend = Pygit2Backend(tmp_dir)
     with pytest.raises(NotImplementedError):
         with backend.get_remote(url):
             pass
+
+
+@pytest.mark.parametrize("name", ["committer", "author"])
+def test_pygit_use_env_vars_for_signature(
+    tmp_dir: TmpDir, mocker: MockerFixture, name: str
+):
+    from pygit2 import Signature
+
+    mocker.patch(
+        "scmrepo.git.Pygit2Backend.default_signature",
+        new=mocker.PropertyMock(side_effect=SCMError),
+    )
+    git = Git.init(tmp_dir)
+    with pytest.raises(SCMError):
+        git.pygit2.default_signature  # pylint: disable=W0104
+
+    # Make sure that the environment variables are not set to not interfere with
+    # with the check below
+    for var in [f"GIT_{name.upper()}_NAME", f"GIT_{name.upper()}_EMAIL"]:
+        assert os.environ.get(var, None) is None
+
+    # Basic expected behavior if vars are not set. Another sanity check
+    with pytest.raises(SCMError):
+        getattr(git.pygit2, name)
+
+    mocker.patch.dict(os.environ, {f"GIT_{name.upper()}_EMAIL": "olivaw@iterative.ai"})
+    with pytest.raises(SCMError):
+        getattr(git.pygit2, name)
+
+    mocker.patch.dict(os.environ, {f"GIT_{name.upper()}_NAME": "R. Daneel Olivaw"})
+    assert getattr(git.pygit2, name) == Signature(
+        email="olivaw@iterative.ai", name="R. Daneel Olivaw"
+    )