fix: marimo edit --sandbox no longer creates new files (#3181)

Fixes #3174

marimo/_cli/sandbox.py

@@ -106,6 +106,8 @@ def _pyproject_toml_to_requirements_txt(
 
 
 def get_dependencies_from_filename(name: str) -> List[str]:
+    if not name or not os.path.exists(name):
+        return []
     try:
         contents, _ = FileContentReader().read_file(name)
         return _get_dependencies(contents) or []
@@ -239,7 +241,7 @@ def run_in_sandbox(
     atexit.register(lambda: os.unlink(temp_file_path))
 
     # Get Python version requirement if available
-    if name is not None:
+    if name is not None and os.path.exists(name):
         contents, _ = FileContentReader().read_file(name)
         pyproject = _read_pyproject(contents)
         python_version = (

tests/_cli/test_cli.py

@@ -549,6 +549,27 @@ def test_cli_sandbox_edit(temp_marimo_file: str) -> None:
     _check_contents(p, b"marimo-mode data-mode='edit'", contents)
 
 
+@pytest.mark.skipif(not HAS_UV, reason="uv is required for sandbox tests")
+def test_cli_sandbox_edit_new_file() -> None:
+    port = _get_port()
+    d = tempfile.TemporaryDirectory()
+    path = os.path.join(d.name, "new_sandbox_file.py")
+    p = subprocess.Popen(
+        [
+            "marimo",
+            "edit",
+            path,
+            "-p",
+            str(port),
+            "--headless",
+            "--no-token",
+            "--sandbox",
+        ]
+    )
+    contents = _try_fetch(port)
+    _check_contents(p, b"marimo-mode data-mode='edit'", contents)
+
+
 @pytest.mark.skipif(not HAS_UV, reason="uv is required for sandbox tests")
 def test_cli_sandbox_run(temp_marimo_file: str) -> None:
     port = _get_port()

tests/_cli/test_sandbox.py

@@ -7,6 +7,7 @@
     _get_python_version_requirement,
     _pyproject_toml_to_requirements_txt,
     _read_pyproject,
+    get_dependencies_from_filename,
 )
 
 
@@ -222,3 +223,11 @@ def test_get_dependencies_with_python_version():
     assert pyproject_no_python is not None
     assert _get_python_version_requirement(pyproject_no_python) is None
     assert _get_dependencies(SCRIPT_NO_PYTHON) == ["polars"]
+
+
+def test_get_dependencies_with_nonexistent_file():
+    # Test with a non-existent file
+    assert get_dependencies_from_filename("nonexistent_file.py") == []
+
+    # Test with None
+    assert get_dependencies_from_filename(None) == []  # type: ignore