langchain/tests/unit_tests/document_loaders/parsers/test_generic.py

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"""Module to test generic parsers."""
from typing import Iterator
import pytest
from langchain.document_loaders.base import BaseBlobParser
from langchain.document_loaders.blob_loaders import Blob
from langchain.document_loaders.parsers.generic import MimeTypeBasedParser
from langchain.schema import Document
class TestMimeBasedParser:
"""Test mime based parser."""
def test_without_fallback_parser(self) -> None:
class FirstCharParser(BaseBlobParser):
def lazy_parse(self, blob: Blob) -> Iterator[Document]:
"""Extract the first character of a blob."""
yield Document(page_content=blob.as_string()[0])
class SecondCharParser(BaseBlobParser):
def lazy_parse(self, blob: Blob) -> Iterator[Document]:
"""Extract the second character of a blob."""
yield Document(page_content=blob.as_string()[1])
parser = MimeTypeBasedParser(
handlers={
"text/plain": FirstCharParser(),
"text/html": SecondCharParser(),
},
)
blob = Blob(data=b"Hello World", mimetype="text/plain")
docs = parser.parse(blob)
assert len(docs) == 1
doc = docs[0]
assert doc.page_content == "H"
# Check text/html handler.
blob = Blob(data=b"Hello World", mimetype="text/html")
docs = parser.parse(blob)
assert len(docs) == 1
doc = docs[0]
assert doc.page_content == "e"
blob = Blob(data=b"Hello World", mimetype="text/csv")
with pytest.raises(ValueError, match="Unsupported mime type"):
# Check that the fallback parser is used when the mimetype is not found.
parser.parse(blob)
def test_with_fallback_parser(self) -> None:
class FirstCharParser(BaseBlobParser):
def lazy_parse(self, blob: Blob) -> Iterator[Document]:
"""Extract the first character of a blob."""
yield Document(page_content=blob.as_string()[0])
class SecondCharParser(BaseBlobParser):
def lazy_parse(self, blob: Blob) -> Iterator[Document]:
"""Extract the second character of a blob."""
yield Document(page_content=blob.as_string()[1])
class ThirdCharParser(BaseBlobParser):
def lazy_parse(self, blob: Blob) -> Iterator[Document]:
"""Extract the third character of a blob."""
yield Document(page_content=blob.as_string()[2])
parser = MimeTypeBasedParser(
handlers={
"text/plain": FirstCharParser(),
"text/html": SecondCharParser(),
},
fallback_parser=ThirdCharParser(),
)
blob = Blob(data=b"Hello World", mimetype="text/plain")
docs = parser.parse(blob)
assert len(docs) == 1
doc = docs[0]
assert doc.page_content == "H"
# Check text/html handler.
blob = Blob(data=b"Hello World", mimetype="text/html")
docs = parser.parse(blob)
assert len(docs) == 1
doc = docs[0]
assert doc.page_content == "e"
# Check that the fallback parser is used when the mimetype is not found.
blob = Blob(data=b"Hello World", mimetype="text/csv")
docs = parser.parse(blob)
assert len(docs) == 1
doc = docs[0]
assert doc.page_content == "l"