Fix: Update parser contract to require empty strings, not None (#12775)

Co-authored-by: stumpylog <797416+stumpylog@users.noreply.github.com>

src/paperless/tests/parsers/test_remote_parser.py

@@ -319,11 +319,11 @@ class TestRemoteParserParse:
         assert remote_parser.get_text() == ""
         assert remote_parser.get_archive_path() is None
 
-    def test_get_text_none_before_parse(
+    def test_get_text_empty_before_parse(
         self,
         remote_parser: RemoteDocumentParser,
     ) -> None:
-        assert remote_parser.get_text() is None
+        assert remote_parser.get_text() == ""
 
     def test_get_date_always_none(
         self,
@@ -342,7 +342,7 @@ class TestRemoteParserParse:
 
 
 class TestRemoteParserParseError:
-    def test_parse_returns_none_on_azure_error(
+    def test_parse_returns_empty_on_azure_error(
         self,
         remote_parser: RemoteDocumentParser,
         simple_digital_pdf_file: Path,
@@ -350,7 +350,7 @@ class TestRemoteParserParseError:
     ) -> None:
         remote_parser.parse(simple_digital_pdf_file, "application/pdf")
 
-        assert remote_parser.get_text() is None
+        assert remote_parser.get_text() == ""
 
     def test_parse_closes_client_on_error(
         self,

src/paperless/tests/parsers/test_text_parser.py

@@ -138,11 +138,11 @@ class TestTextParserParse:
 
         assert text_parser.get_text() == "Pantothens\ufffdure\n"
 
-    def test_get_text_none_before_parse(
+    def test_get_text_empty_before_parse(
         self,
         text_parser: TextDocumentParser,
     ) -> None:
-        assert text_parser.get_text() is None
+        assert text_parser.get_text() == ""
 
 
 class TestTextParserThumbnail:

src/paperless/tests/test_registry.py

@@ -74,8 +74,8 @@ def dummy_parser_cls() -> type:
             Required to exist, but doesn't need to do anything
             """
 
-        def get_text(self) -> str | None:
-            return None
+        def get_text(self) -> str:
+            return ""
 
         def get_date(self) -> None:
             return None