MAINT: Allow opening PdfReader as contextmanager

To mirror PdfWriter, also hints towards file pointer management now that
we keep files open sometimes.

pypdf/_reader.py

@@ -32,6 +32,7 @@
 import weakref
 from io import BytesIO, FileIO, UnsupportedOperation
 from pathlib import Path
+from types import TracebackType
 from typing import (
     Any,
     Callable,
@@ -40,6 +41,7 @@
     List,
     Optional,
     Tuple,
+    Type,
     Union,
     cast,
 )
@@ -100,6 +102,9 @@ class PdfReader(PdfDocCommon):
         password: Decrypt PDF file at initialization. If the
             password is None, the file will not be decrypted.
             Defaults to ``None``.
+
+    Can also be instantiated as a contextmanager which will automatically close
+    the underlying file pointer if passed via filenames.
     """
 
     def __init__(
@@ -123,8 +128,10 @@ def __init__(
                 __name__,
             )
 
+        self._opened_automatically = False
         if isinstance(stream, (str, Path)):
             stream = FileIO(stream, "rb")
+            self._opened_automatically = True
             weakref.finalize(self, stream.close)
 
         self.read(stream)
@@ -160,6 +167,20 @@ def close(self) -> None:
         """Close the underlying file handle"""
         self.stream.close()
 
+    def __enter__(self) -> "PdfReader":
+        """Use PdfReader as context manager"""
+        return self
+
+    def __exit__(
+        self,
+        exc_type: Optional[Type[BaseException]],
+        exc: Optional[BaseException],
+        traceback: Optional[TracebackType],
+    ) -> None:
+        """Close the underlying stream if owned by the PdfReader"""
+        if self._opened_automatically:
+            self.close()
+
     @property
     def root_object(self) -> DictionaryObject:
         """Provide access to "/Root". standardized with PdfWriter."""

tests/test_reader.py

@@ -853,8 +853,8 @@ def test_extract_text_hello_world():
 
 def test_read_path():
     path = Path(RESOURCE_ROOT, "crazyones.pdf")
-    reader = PdfReader(path)
-    assert len(reader.pages) == 1
+    with PdfReader(path) as reader:
+        assert len(reader.pages) == 1
 
 
 def test_read_not_binary_mode(caplog):