Fix third-party package detection

Author: codeSamuraii

pyfuse/__main__.py

@@ -20,6 +20,7 @@
 import logging
 import argparse
 import importlib
+import importlib.machinery
 from pathlib import Path
 from collections.abc import Callable
 from importlib.metadata import version as pkg_version
@@ -200,13 +201,24 @@ def _parse_script(script: str) -> tuple[str, ast.Module | None]:
 
 
 def _is_local_package(module_name: str, script_dir: str) -> bool:
-    """Return True if *module_name* resolves to a local directory or .py file."""
-    for base in (Path(script_dir), Path.cwd()):
-        if (base / module_name).is_dir():
-            return True
-        if (base / f"{module_name}.py").is_file():
-            return True
-    return False
+    """Return True if *module_name* is importable from the script's runtime path.
+
+    The script will be launched with ``cwd`` and its own directory on
+    ``sys.path`` (see ``_build_script_env``); we ask Python's path-based finder
+    whether the name resolves on exactly that list. We do not mutate
+    ``sys.path`` or ``sys.modules``.
+
+    If the module isn't found, we leave it alone and let the script fail at
+    runtime with the standard ``ModuleNotFoundError`` — that error names the
+    missing module and is the clearest signal to the user that their layout or
+    invocation directory is wrong.
+    """
+    search_path = [script_dir, str(Path.cwd())]
+    try:
+        spec = importlib.machinery.PathFinder.find_spec(module_name, search_path)
+    except (ImportError, ValueError):
+        return False
+    return spec is not None
 
 
 def _extract_top_modules(node: ast.AST) -> list[str]:

pyfuse/core/progress.py

@@ -81,7 +81,9 @@ def progress(
     if cb is None:
         return
 
-    if _total is not None:
+    if isinstance(_total, (int, float)):
+        if _total <= 0:
+            raise ValueError("Progress total must be a positive number.")
         # current / total form
         cb(_value, _total, message)
     else:

tests/test_venv.py

@@ -184,6 +184,49 @@ def test_skips_local_module_file(self, tmp_path: pytest.TempPathFactory) -> None
         assert "requests" in packages
         assert "helpers" not in packages
 
+    def test_skips_local_package_reachable_via_cwd(
+        self, tmp_path: pytest.TempPathFactory, monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """A sibling package importable from cwd is treated as local.
+
+        Mirrors ``pyfuse run examples/foo.py`` invoked from the project root,
+        where ``foo.py`` imports a package living at that root.
+        """
+        sibling_pkg = tmp_path / "mypkg"  # type: ignore[operator]
+        sibling_pkg.mkdir()
+        (sibling_pkg / "__init__.py").write_text("")
+
+        scripts_dir = tmp_path / "scripts"  # type: ignore[operator]
+        scripts_dir.mkdir()
+        script = scripts_dir / "run.py"
+        script.write_text("from mypkg import thing\nimport requests\n")
+
+        monkeypatch.chdir(tmp_path)
+        packages = _detect_script_packages(str(script))
+        assert "requests" in packages
+        assert "mypkg" not in packages
+
+    def test_treats_unreachable_package_as_third_party(
+        self, tmp_path: pytest.TempPathFactory, monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """If a module isn't importable from cwd or the script dir, leave it alone:
+        the script will fail at runtime with a clear ImportError, and the user is
+        responsible for fixing their layout (we don't silently rewrite imports)."""
+        # ``mypkg`` lives one level up from cwd and isn't on sys.path.
+        sibling_pkg = tmp_path / "mypkg"  # type: ignore[operator]
+        sibling_pkg.mkdir()
+        (sibling_pkg / "__init__.py").write_text("")
+
+        scripts_dir = tmp_path / "scripts"  # type: ignore[operator]
+        scripts_dir.mkdir()
+        script = scripts_dir / "run.py"
+        script.write_text("from mypkg import thing\n")
+
+        monkeypatch.chdir(scripts_dir)
+        packages = _detect_script_packages(str(script))
+        # mypkg can't be imported from cwd or script_dir → treated as third-party.
+        assert "mypkg" in packages
+
     def test_install_package_as(self, tmp_path: pytest.TempPathFactory) -> None:
         script = tmp_path / "test_ipa.py"  # type: ignore[operator]
         script.write_text(