Use finally to clean temporary remote

setup.cfg

@@ -32,6 +32,7 @@ install_requires=
     pathspec>=0.9.0
     asyncssh>=2.7.1,<3
     funcy>=1.14
+    shortuuid>=0.5.0
 
 [options.extras_require]
 tests =

src/scmrepo/git/__init__.py

@@ -41,6 +41,8 @@ def __getitem__(self, key: str) -> BaseGitBackend:
         """Lazily initialize backends and cache it afterwards"""
         initialized = self.initialized.get(key)
         if not initialized:
+            if key not in self.backends and key in self.DEFAULT:
+                raise NotImplementedError
             backend = self.backends[key]
             initialized = backend(*self.args, **self.kwargs)
             self.initialized[key] = initialized
@@ -278,7 +280,7 @@ def _backend_func(self, name, *args, **kwargs):
                 self._last_backend = key
                 self.backends.move_to_end(key, last=False)
                 return result
-            except (NotImplementedError, KeyError):
+            except NotImplementedError:
                 pass
         raise NoGitBackendError(name)
 

src/scmrepo/git/backend/pygit2.py

@@ -8,6 +8,7 @@
     TYPE_CHECKING,
     Callable,
     Dict,
+    Generator,
     Iterable,
     List,
     Mapping,
@@ -17,6 +18,7 @@
 )
 
 from funcy import cached_property, reraise
+from shortuuid import uuid
 
 from scmrepo.exceptions import CloneError, MergeConflictError, RevError, SCMError
 from scmrepo.utils import relpath
@@ -448,6 +450,19 @@ def _merge_remote_branch(
         logger.debug("Unexpected merge result: %s", pygit2.GIT_MERGE_ANALYSIS_NORMAL)
         raise SCMError("Unknown merge analysis result")
 
+    @contextmanager
+    def get_remote(self, url: str) -> Generator["Remote", None, None]:
+        try:
+            yield self.repo.remotes[url]
+        except ValueError:
+            try:
+                remote_name = uuid()
+                yield self.repo.remotes.create(remote_name, url)
+            finally:
+                self.repo.remotes.delete(remote_name)
+        except KeyError:
+            raise SCMError(f"'{url}' is not a valid Git remote or URL")
+
     def fetch_refspecs(
         self,
         url: str,
@@ -462,60 +477,52 @@ def fetch_refspecs(
         if isinstance(refspecs, str):
             refspecs = [refspecs]
 
-        try:
-            remote: "Remote" = self.repo.remotes[url]
-        except ValueError:
-            remote_name = "fetch"
-            self.repo.remotes.set_url(remote_name, url)
-            remote = self.repo.remotes[remote_name]
-        except KeyError:
-            raise SCMError(f"'{url}' is not a valid Git remote or URL")
+        with self.get_remote(url) as remote:
+            if os.name == "nt" and remote.url.startswith("ssh://"):
+                raise NotImplementedError
 
-        if os.name == "nt" and remote.url.startswith("ssh://"):
-            raise NotImplementedError
+            if os.name == "nt" and remote.url.startswith("file://"):
+                url = remote.url[len("file://") :]
+                self.repo.remotes.set_url(remote.name, url)
+                remote = self.repo.remotes[remote.name]
 
-        if os.name == "nt" and remote.url.startswith("file://"):
-            url = remote.url[len("file://") :]
-            self.repo.remotes.set_url(remote.name, url)
-            remote = self.repo.remotes[remote.name]
-
-        fetch_refspecs: List[str] = []
-        for refspec in refspecs:
-            if ":" in refspec:
-                lh, rh = refspec.split(":")
-            else:
-                lh = rh = refspec
-            if not rh.startswith("refs/"):
-                rh = f"refs/heads/{rh}"
-            if not lh.startswith("refs/"):
-                lh = f"refs/heads/{lh}"
-            rh = rh[len("refs/") :]
-            refspec = f"+{lh}:refs/remotes/{remote.name}/{rh}"
-            fetch_refspecs.append(refspec)
-
-        logger.debug("fetch_refspecs: %s", fetch_refspecs)
-        with reraise(
-            GitError,
-            SCMError(f"Git failed to fetch ref from '{url}'"),
-        ):
-            remote.fetch(refspecs=fetch_refspecs)
-
-        result: Dict[str, "SyncStatus"] = {}
-        for refspec in fetch_refspecs:
-            _, rh = refspec.split(":")
-            if not rh.endswith("*"):
-                refname = rh.split("/", 3)[-1]
-                refname = f"refs/{refname}"
-                result[refname] = self._merge_remote_branch(
-                    rh, refname, force, on_diverged
-                )
-                continue
-            rh = rh.rstrip("*").rstrip("/") + "/"
-            for branch in self.iter_refs(base=rh):
-                refname = f"refs/{branch[len(rh):]}"
-                result[refname] = self._merge_remote_branch(
-                    branch, refname, force, on_diverged
-                )
+            fetch_refspecs: List[str] = []
+            for refspec in refspecs:
+                if ":" in refspec:
+                    lh, rh = refspec.split(":")
+                else:
+                    lh = rh = refspec
+                if not rh.startswith("refs/"):
+                    rh = f"refs/heads/{rh}"
+                if not lh.startswith("refs/"):
+                    lh = f"refs/heads/{lh}"
+                rh = rh[len("refs/") :]
+                refspec = f"+{lh}:refs/remotes/{remote.name}/{rh}"
+                fetch_refspecs.append(refspec)
+
+            logger.debug("fetch_refspecs: %s", fetch_refspecs)
+            with reraise(
+                GitError,
+                SCMError(f"Git failed to fetch ref from '{url}'"),
+            ):
+                remote.fetch(refspecs=fetch_refspecs)
+
+            result: Dict[str, "SyncStatus"] = {}
+            for refspec in fetch_refspecs:
+                _, rh = refspec.split(":")
+                if not rh.endswith("*"):
+                    refname = rh.split("/", 3)[-1]
+                    refname = f"refs/{refname}"
+                    result[refname] = self._merge_remote_branch(
+                        rh, refname, force, on_diverged
+                    )
+                    continue
+                rh = rh.rstrip("*").rstrip("/") + "/"
+                for branch in self.iter_refs(base=rh):
+                    refname = f"refs/{branch[len(rh):]}"
+                    result[refname] = self._merge_remote_branch(
+                        branch, refname, force, on_diverged
+                    )
         return result
 
     def _stash_iter(self, ref: str):

tests/test_git.py

@@ -367,6 +367,8 @@ def test_fetch_refspecs(
         mocker.patch.object(Remote, "fetch", side_effect=GitError)
         git.fetch_refspecs(remote, "refs/foo/bar:refs/foo/bar")
 
+    assert len(scm.pygit2.repo.remotes) == 1
+
 
 @pytest.mark.skip_git_backend("pygit2", "gitpython")
 @pytest.mark.parametrize("use_url", [True, False])