Add open_file method environment (#23)

binharness/localenvironment.py

@@ -5,7 +5,7 @@
 import subprocess
 import tempfile
 from pathlib import Path
-from typing import TYPE_CHECKING, Sequence
+from typing import TYPE_CHECKING, AnyStr, Sequence
 
 from binharness.types.environment import Environment
 from binharness.types.process import Process
@@ -66,6 +66,10 @@ def get_tempdir(self: LocalEnvironment) -> Path:
         """Get a Path for a temporary directory."""
         return Path(tempfile.gettempdir())
 
+    def open_file(self: Environment, path: Path, mode: str) -> IO[AnyStr]:
+        """Open a file in the environment. Follows the same semantics as `open`."""
+        return Path.open(path, mode)
+
 
 class LocalProcess(Process):
     """A process running in a local environment."""

binharness/types/environment.py

@@ -2,12 +2,12 @@
 from __future__ import annotations
 
 from abc import ABC, abstractmethod
-from typing import TYPE_CHECKING, Sequence
+from typing import TYPE_CHECKING, AnyStr, Sequence
 
 if TYPE_CHECKING:
     from pathlib import Path
 
-    from binharness import BusyboxInjection, Process
+    from binharness import IO, BusyboxInjection, Process
 
 
 class BusyboxInjectionNotInstalledError(Exception):
@@ -86,3 +86,8 @@ def retrieve_files(
     def get_tempdir(self: Environment) -> Path:
         """Get a Path for a temporary directory."""
         raise NotImplementedError
+
+    @abstractmethod
+    def open_file(self: Environment, path: Path, mode: str) -> IO[AnyStr]:
+        """Open a file in the environment. Follows the same semantics as `open`."""
+        raise NotImplementedError