ENH: Allow setting the decryption password in PdfReader.__init__ (#920)

This is a convenience change. You can still call `reader = PdfReader("encrypted.pdf"); reader.decrypt(password)`.

Full credit to pubpub-zz; I just made stylistic changes.

Closes #910 

Co-authored-by: pubpub-zz <[email protected]>

PyPDF2/_reader.py

@@ -231,9 +231,17 @@ class PdfReader:
     :param bool strict: Determines whether user should be warned of all
         problems and also causes some correctable problems to be fatal.
         Defaults to ``False``.
+    :param None/str/bytes password: Decrypt PDF file at initialization. If the
+        password is None, the file will not be decrypted.
+        Defaults to ``None``
     """
 
-    def __init__(self, stream: StrByteType, strict: bool = False) -> None:
+    def __init__(
+        self,
+        stream: StrByteType,
+        strict: bool = False,
+        password: Union[None, str, bytes] = None,
+    ) -> None:
         self.strict = strict
         self.flattened_pages: Optional[List[PageObject]] = None
         self.resolved_objects: Dict[Tuple[Any, Any], Optional[PdfObject]] = {}
@@ -254,6 +262,8 @@ def __init__(self, stream: StrByteType, strict: bool = False) -> None:
         self.stream = stream
 
         self._override_encryption = False
+        if password is not None and self.decrypt(password) == 0:
+            raise PdfReadError("Wrong password")
 
     @property
     def metadata(self) -> Optional[DocumentInformation]:

tests/test_reader.py

@@ -254,20 +254,22 @@ def test_issue297():
     reader.pages[0]
 
 
-def test_get_page_of_encrypted_file():
+@pytest.mark.parametrize(
+    ("password", "should_fail"), [("test", False), ("qwerty", True)]
+)
+def test_get_page_of_encrypted_file(password, should_fail):
     """
     Check if we can read a page of an encrypted file.
 
     This is a regression test for issue 327:
     IndexError for get_page() of decrypted file
     """
     path = os.path.join(RESOURCE_ROOT, "encrypted-file.pdf")
-    reader = PdfReader(path)
-
-    # Password is correct:)
-    reader.decrypt("test")
-
-    reader.pages[0]
+    if should_fail:
+        with pytest.raises(PdfReadError):
+            PdfReader(path, password=password)
+    else:
+        PdfReader(path, password=password).pages[0]
 
 
 @pytest.mark.parametrize(