Method syspath_prepend

src/_pytest/monkeypatch.py:337–377

Prepend ``path`` to ``sys.path`` list of import locations.

(self, path)

        self.delitem(environ, name, raising=raising)

    def syspath_prepend(self, path) -> None:
        """Prepend ``path`` to ``sys.path`` list of import locations."""
        if self._savesyspath is None:
            self._savesyspath = sys.path[:]
        sys.path.insert(0, str(path))

        # https://github.com/pypa/setuptools/blob/d8b901bc/docs/pkg_resources.txt#L162-L171
        # this is only needed when pkg_resources was already loaded by the namespace package
        if "pkg_resources" in sys.modules:
            import pkg_resources
            from pkg_resources import fixup_namespace_packages

            # Only issue deprecation warning if this call would actually have an
            # effect for this specific path.
            if (
                hasattr(pkg_resources, "_namespace_packages")
                and pkg_resources._namespace_packages
            ):
                path_obj = Path(str(path))
                for ns_pkg in pkg_resources._namespace_packages:
                    if ns_pkg is None:
                        continue
                    ns_pkg_path = path_obj / ns_pkg.replace(".", os.sep)
                    if ns_pkg_path.is_dir():
                        warnings.warn(
                            MONKEYPATCH_LEGACY_NAMESPACE_PACKAGES, stacklevel=2
                        )
                        break

            fixup_namespace_packages(str(path))

        # A call to syspathinsert() usually means that the caller wants to
        # import some dynamically created files, thus with python3 we
        # invalidate its import caches.
        # This is especially important when any namespace package is in use,
        # since then the mtime based FileFinder cache (that gets created in
        # this case already) gets not invalidated when writing the new files
        # quickly afterwards.
        from importlib import invalidate_caches

        invalidate_caches()

    def chdir(self, path: str | os.PathLike[str]) -> None:
        """Change the current working directory to the specified path.