refactoring

src/poetry/installation/installer.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import contextlib
 import os
 
 from typing import TYPE_CHECKING
@@ -606,15 +607,8 @@ def set_lock_data(self, root: Package, packages: list[Package]) -> bool:
         # to make sure we have permissions later.
         self._lock_data = self._locker.compute_lock_data(root, packages)
 
-        # On verify if we can write to the lock file, an `open(lock, "a")` is enough.
-        # However, in case of no lock file exists and the installation fails, then an
-        # empty poetry.lock would be kept in the filesystem.
-        # So, a non-intrusive approach is done here to emulate what `open` would do.
         if self._should_write():
-            path = self._locker.lock
-            path = path if self.is_locked() else path.parent
-            if not os.access(path, os.W_OK):
-                raise PermissionError(f"Permission denied on writing to file '{path}'")
+            self._check_writable()
             return True
 
         return False
@@ -627,12 +621,19 @@ def rollback(self) -> None:
         self._lock_data = None
 
     def _should_write(self) -> bool:
+        # if lock file exists: compare new lock data with old lock data
         if self.is_locked():
-            try:
-                old_lock_data = self._locker.lock_data
-            except RuntimeError:
-                # incompatible, invalid or no lock file
-                pass
-            else:
-                return self._lock_data != old_lock_data
+            with contextlib.suppress(RuntimeError):
+                # error happens when incompatible, invalid or no lock file
+                return self._lock_data != self._locker.lock_data
         return True
+
+    def _check_writable(self) -> None:
+        # On verify if lock file is writable, an `open(path, "a")` would be enough.
+        # However, in case of no lock file exists and the installation fails, then an
+        # empty poetry.lock would be kept in the filesystem.
+        # So, a non-intrusive approach is done here to emulate what `open` would do.
+        path = self._locker.lock
+        path = path if path.is_file() else path.parent
+        if not os.access(path, os.W_OK):
+            raise PermissionError(f"Permission denied on writing to file '{path}'")