perf: optimize status method with first commit check

Add _is_first_commit helper and update tests accordingly

Author: dualc

jupyterlab_git/git.py

@@ -486,6 +486,14 @@ def remove_cell_ids(nb):
 
             return {"base": prev_nb, "diff": thediff}
 
+    async def _is_first_commit(self, path: str) -> bool:
+        """Return True if repo has no commits yet."""
+        code, _, _ = await self.__execute(
+            ["git", "rev-parse", "--verify", "HEAD"], cwd=path
+        )
+        return code != 0
+
+
     async def status(self, path: str) -> dict:
         """
         Execute git status command & return the result.
@@ -501,14 +509,20 @@ async def status(self, path: str) -> dict:
             }
 
         # Add attribute `is_binary`
-        command = [  # Compare stage to an empty tree see `_is_binary`
-            "git",
-            "diff",
-            "--numstat",
-            "-z",
-            "--cached",
-            "4b825dc642cb6eb9a060e54bf8d69288fbee4904",
-        ]
+        first_commit = await self._is_first_commit(path)
+        if first_commit:
+            # only first commit has to compare to an empty tree
+            command = [  # Compare stage to an empty tree see `_is_binary`
+                "git",
+                "diff",
+                "--numstat",
+                "-z",
+                "--cached",
+                "4b825dc642cb6eb9a060e54bf8d69288fbee4904",
+            ]
+        else:
+            command = ["git", "diff", "--numstat", "-z", "--cached"]
+
         text_code, text_output, _ = await self.__execute(command, cwd=path)
 
         are_binary = dict()

jupyterlab_git/tests/test_status.py

@@ -353,9 +353,18 @@ async def test_status(tmp_path, output, diff_output, expected):
         repository = tmp_path / "test_curr_path"
         (repository / ".git" / "rebase-merge").mkdir(parents=True)
 
+        # Determine if this is a first commit scenario
+        is_first_commit = expected.get("branch") == "(initial)"
+        
+        # Build mock_execute.side_effect list
+        # First: git status call
+        # Second: git rev-parse --verify HEAD (for _is_first_commit)
+        # Third: git diff call (with or without empty tree SHA based on is_first_commit)
+        # Then: state detection calls (cherry pick, merge, rebase)
         mock_execute.side_effect = [
-            maybe_future((0, "\x00".join(output) + "\x00", "")),
-            maybe_future((0, "\x00".join(diff_output) + "\x00", "")),
+            maybe_future((0, "\x00".join(output) + "\x00", "")),  # git status
+            maybe_future((128 if is_first_commit else 0, "", "")),  # git rev-parse --verify HEAD
+            maybe_future((0, "\x00".join(diff_output) + "\x00", "")),  # git diff
             maybe_future((0 if expected["state"] == 4 else 128, "", "cherry pick")),
             maybe_future((0 if expected["state"] == 2 else 128, "", "merge")),
             maybe_future(
@@ -381,21 +390,57 @@ async def test_status(tmp_path, output, diff_output, expected):
                 is_binary=False,
             ),
             call(
-                [
-                    "git",
-                    "diff",
-                    "--numstat",
-                    "-z",
-                    "--cached",
-                    "4b825dc642cb6eb9a060e54bf8d69288fbee4904",
-                ],
+                ["git", "rev-parse", "--verify", "HEAD"],
                 cwd=str(repository),
                 timeout=20,
                 env=None,
                 username=None,
                 password=None,
                 is_binary=False,
             ),
+        ]
+        
+        # Add diff command based on whether it's first commit
+        if is_first_commit:
+            expected_calls.append(
+                call(
+                    [
+                        "git",
+                        "diff",
+                        "--numstat",
+                        "-z",
+                        "--cached",
+                        "4b825dc642cb6eb9a060e54bf8d69288fbee4904",
+                    ],
+                    cwd=str(repository),
+                    timeout=20,
+                    env=None,
+                    username=None,
+                    password=None,
+                    is_binary=False,
+                )
+            )
+        else:
+            expected_calls.append(
+                call(
+                    [
+                        "git",
+                        "diff",
+                        "--numstat",
+                        "-z",
+                        "--cached",
+                    ],
+                    cwd=str(repository),
+                    timeout=20,
+                    env=None,
+                    username=None,
+                    password=None,
+                    is_binary=False,
+                )
+            )
+        
+        # Add state detection calls
+        expected_calls.extend([
             call(
                 ["git", "show", "--quiet", "CHERRY_PICK_HEAD"],
                 cwd=str(repository),
@@ -432,7 +477,7 @@ async def test_status(tmp_path, output, diff_output, expected):
                 password=None,
                 is_binary=False,
             ),
-        ]
+        ])
 
         if expected["state"] == 4:
             expected_calls = expected_calls[:-3]