Avoid 500 error messages when current working directory in Jupyter Lab is not a git repo (#855)

* Avoid 500 error messages when cwd is not git repo

Avoid long 500 error messages in terminal when current working directory in Jupyter Lab is not a git repository.
Instead, print a message to terminal (`self.log.info`) of the git error message `fatal: not a git repository (or any of the parent directories):`
Discussed: #842

Author: jeanmonet

jupyterlab_git/git.py

@@ -682,6 +682,11 @@ async def show_top_level(self, current_path):
         if code == 0:
             return {"code": code, "top_repo_path": my_output.strip("\n")}
         else:
+            # Handle special case where cwd not inside a git repo
+            lower_error = my_error.lower()
+            if "fatal: not a git repository" in lower_error:
+                return {"code": 0, "top_repo_path": None}
+
             return {
                 "code": code,
                 "command": " ".join(cmd),

jupyterlab_git/handlers.py

@@ -74,7 +74,7 @@ async def post(self):
         history_count = body["history_count"]
 
         show_top_level = await self.git.show_top_level(current_path)
-        if show_top_level["code"] != 0:
+        if show_top_level.get("top_repo_path") is None:
             self.set_status(500)
             self.finish(json.dumps(show_top_level))
         else:

jupyterlab_git/tests/test_handlers.py

@@ -28,7 +28,7 @@ def test_mapping_added():
 @patch("jupyterlab_git.handlers.GitAllHistoryHandler.git", spec=Git)
 async def test_all_history_handler_localbranch(mock_git, jp_fetch):
     # Given
-    show_top_level = {"code": 0, "foo": "top_level"}
+    show_top_level = {"code": 0, "top_repo_path": "foo"}
     branch = "branch_foo"
     log = "log_foo"
     status = "status_foo"
@@ -61,6 +61,66 @@ async def test_all_history_handler_localbranch(mock_git, jp_fetch):
     }
 
 
+@patch("jupyterlab_git.git.execute")
+async def test_git_show_top_level(mock_execute, jp_fetch, jp_root_dir):
+    # Given
+    top_repo_path = "path/to/repo"
+
+    mock_execute.return_value = maybe_future((0, str(top_repo_path), ""))
+
+    # When
+    body = {
+        "current_path": top_repo_path + "/subfolder",
+    }
+    response = await jp_fetch(
+        NS, "show_top_level", body=json.dumps(body), method="POST"
+    )
+
+    # Then
+    assert response.code == 200
+    payload = json.loads(response.body)
+    assert payload["top_repo_path"] == top_repo_path
+    mock_execute.assert_has_calls(
+        [
+            call(
+                ["git", "rev-parse", "--show-toplevel"],
+                cwd=str(jp_root_dir / top_repo_path / "subfolder"),
+            ),
+        ]
+    )
+
+
+@patch("jupyterlab_git.git.execute")
+async def test_git_show_top_level_not_a_git_repo(mock_execute, jp_fetch, jp_root_dir):
+    # Given
+    top_repo_path = "path/to/repo"
+
+    mock_execute.return_value = maybe_future(
+        (128, "", "fatal: not a git repository (or any")
+    )
+
+    # When
+    body = {
+        "current_path": top_repo_path + "/subfolder",
+    }
+    response = await jp_fetch(
+        NS, "show_top_level", body=json.dumps(body), method="POST"
+    )
+
+    # Then
+    assert response.code == 200
+    payload = json.loads(response.body)
+    assert payload["top_repo_path"] is None
+    mock_execute.assert_has_calls(
+        [
+            call(
+                ["git", "rev-parse", "--show-toplevel"],
+                cwd=str(jp_root_dir / top_repo_path / "subfolder"),
+            ),
+        ]
+    )
+
+
 @patch("jupyterlab_git.handlers.GitBranchHandler.git", spec=Git)
 async def test_branch_handler_localbranch(mock_git, jp_fetch):
     # Given